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  • 101.
    Grundström, Hanna
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Nursing Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center of Paediatrics and Gynaecology and Obstetrics, Department of Gynaecology and Obstetrics in Norrköping.
    Larsson, Britt
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Arendt-Nielsen, Lars
    Aalborg Univ, Denmark.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Kjölhede, Preben
    Linköping University, Department of Clinical and Experimental Medicine, Division of Children's and Women's health. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center of Paediatrics and Gynaecology and Obstetrics, Department of Gynaecology and Obstetrics in Linköping.
    Associations between pain thresholds for heat, cold and pressure, and Pain Sensitivity Questionnaire scores in healthy women and in women with persistent pelvic pain2019In: European Journal of Pain, ISSN 1090-3801, E-ISSN 1532-2149Article in journal (Refereed)
    Abstract [en]

    Background

    The Pain Sensitivity Questionnaire (PSQ) is a self‐rating instrument developed as a time‐ and cost‐saving alternative to quantitative sensory testing (QST). The aims of the study were to assess (a) the associations between PSQ scores and QST in women with persistent pelvic pain and in pain‐free controls and (b) to what extent demographic variables and psychological distress influenced PSQ scores.

    Methods

    Fifty‐five healthy women and 37 women with persistent pelvic pain participated. All filled in the PSQ and Hospital Anxiety and Depression Scale and had QST (heat, cold and pressure pain thresholds) performed on six locations on the body. Information on age, body mass index, smoking habits and pain duration were collected. Principal component analysis and orthogonal partial least square regressions were used.

    Results

    The patients scored significantly higher on PSQ than the controls. Significant multivariate correlations between pain thresholds and PSQ scores were found only in the patient group. In the patient group, the heat and cold pain thresholds correlated more strongly with PSQ scores than the pressure pain threshold.

    Conclusions

    The PSQ score was significantly higher in pelvic pain patients, and correlations between QSTs and the PSQ were only found for patients.

    Significance

    The PSQ reflects pain sensitivity in women with PPP and can be used as a non‐invasive and painless way to assess this condition in clinical practice.

    The full text will be freely available from 2020-06-13 15:39
  • 102.
    Gullaksen, Ann-Christine
    et al.
    Malmö högskola.
    Gerdle, Björn
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Multimodal rehabilitering vid långvarig smärta . systematisk översikt från SBU2006In: Svensk rehabilitering, ISSN 1403-4468, Vol. 2, p. 18-21Article in journal (Refereed)
    Abstract [sv]

       

  • 103.
    Hadrevi, J
    et al.
    Umeå University, Sweden .
    Ghafouri, Bijar
    Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Östergötlands Läns Landsting, Heart and Medicine Center, Occupational and Environmental Medicine Center. Linköping University, Department of Medical and Health Sciences, Division of Community Medicine.
    Sjörs, Anna
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences.
    Antti, H
    Umeå University, Sweden .
    Larsson, Britt
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Crenshaw, A G.
    University of Gavle, Sweden .
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Hellstrom, F
    University of Gavle, Sweden .
    Comparative metabolomics of muscle interstitium fluid in human trapezius myalgia: an in vivo microdialysis study2013In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 113, no 12, p. 2977-2989Article in journal (Refereed)
    Abstract [en]

    The mechanisms behind trapezius myalgia are unclear. Many hypotheses have been presented suggesting an altered metabolism in the muscle. Here, muscle microdialysate from healthy and myalgic muscle is analysed using metabolomics. Metabolomics analyse a vast number of metabolites, enabling a comprehensive explorative screening of the cellular processes in the muscle. less thanbrgreater than less thanbrgreater thanMicrodialysate samples were obtained from the shoulder muscle of healthy and myalgic subjects that performed a work and stress test. Samples from the baseline period and from the recovery period were analysed using gas chromatography-mass spectrometry (GC-MS) together with multivariate analysis to detect differences in extracellular content of metabolites between groups. Systematic differences in metabolites between groups were identified using multivariate analysis and orthogonal partial least square discriminate analysis (OPLS-DA). A complementary Mann-Whitney U test of group difference in individual metabolites was also performed. less thanbrgreater than less thanbrgreater thanA large number of metabolites were detected and identified in this screening study. At baseline, no systematic differences between groups were observed according to the OPLS-DA. However, two metabolites, l-leucine and pyroglutamic acid, were significantly more abundant in the myalgic muscle compared to the healthy muscle. In the recovery period, systematic difference in metabolites between the groups was observed according to the OPLS-DA. The groups differed in amino acids, fatty acids and carbohydrates. Myristic acid and putrescine were significantly more abundant and beta-d-glucopyranose was significantly less abundant in the myalgic muscle. less thanbrgreater than less thanbrgreater thanThis study provides important information regarding the metabolite content, thereby presenting new clues regarding the pathophysiology of the myalgic muscle.

  • 104.
    Hadrevi, Jenny
    et al.
    Umeå University, Sweden.
    Ghafouri, Bijar
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Östergötlands Läns Landsting, Heart and Medicine Center, Occupational and Environmental Medicine Center.
    Larsson, Britt
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Hellstrom, Fredrik
    University of Gävle, Sweden.
    Multivariate Modeling of Proteins Related to Trapezius Myalgia, a Comparative Study of Female Cleaners with or without Pain2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 9Article in journal (Refereed)
    Abstract [en]

    The prevalence of chronic trapezius myalgia is high in women with high exposure to awkward working positions, repetitive movements and movements with high precision demands. The mechanisms behind chronic trapezius myalgia are not fully understood. The purpose of this study was to explore the differences in protein content between healthy and myalgic trapezius muscle using proteomics. Muscle biopsies from 12 female cleaners with work-related trapezius myalgia and 12 pain free female cleaners were obtained from the descending part of the trapezius. Proteins were separated with two-dimensional differential gel electrophoresis (2D-DIGE) and selected proteins were identified with mass spectrometry. In order to discriminate the two groups, quantified proteins were fitted to a multivariate analysis: partial least square discriminate analysis. The model separated 28 unique proteins which were related to glycolysis, the tricaboxylic acid cycle, to the contractile apparatus, the cytoskeleton and to acute response proteins. The results suggest altered metabolism, a higher abundance of proteins related to inflammation in myalgic cleaners compared to healthy, and a possible alteration of the contractile apparatus. This explorative proteomic screening of proteins related to chronic pain in the trapezius muscle provides new important aspects of the pathophysiology behind chronic trapezius myalgia.

  • 105.
    Hadrévi, Jenny
    et al.
    Umeå University, Sweden.
    Turkina, Maria
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Carlsson, Anders
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Linköping University, Faculty of Medicine and Health Sciences.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Larsson, Britt
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Hellström, Fredrik
    University of Gävle, Sweden.
    Ghafouri, Bijar
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Myosin light chain and calcium regulating protein differences in chronic musculoskeletal neck and shoulder pain2016In: Journal of Integrated OMICS, ISSN 2182-0287, Vol. 6, no 1, p. 1-8Article in journal (Refereed)
    Abstract [en]

    Proteomic screening analysis has detected myosin light chain (MLC) as a protein implied to be involved in chronic musculoskeletal neck and shoulder pain. Several analyses of MLC proteins have stated a difference in phosphorylation being the determining factor for protein activation hence altered contrability of the muscle in i.e. senescence. In continuation of a previous publication, this study is an attempt to analyze the different MLC isoforms by mass spectrometry and immune-analyses in myalgic and healthy trapezius muscle. In the present study no differences in phosphorylation level between the corresponding individual proteins were detected using LC-MSMS and immunoblotting; instead we assigned different isoforms of regulatory MLCs. To further elucidate the contrability: calcium (Ca2+) regulatory proteins, sarco(endo)plasmic reticulum Ca2+ ATPase 1 (SERCA-1) and calsequestrine (CSQ) were analyzed by western blot. The analysis revealed a significantly increased abundance of SERCA-1 protein in the myalgic muscle and a significantly increased abundance of CSQ in healthy muscle. Myalgic muscle contraction patterns have in previous studies shown to differ from healthy muscle which may be connected to the Ca2+ availability in the muscle. Here we present the proteomic characterization of differences in Ca2+ regulating proteins and particularly regulatory MLCs in trapezius muscle of women with chronic musculoskeletal neck and shoulder pain.

  • 106.
    Henriksson, Chris
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Occupational Therapy.
    Liedberg, Gunilla
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Occupational Therapy.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Women with fibromyalgia: Work and rehabilitation2005In: Disability and Rehabilitation, ISSN 0963-8288, E-ISSN 1464-5165, Vol. 27, no 12, p. 685-695Article in journal (Refereed)
    Abstract [en]

    Purpose. To explore disability in women with fibromyalgia with a focus on their work situation. Method. Review of literature on work status of women with fibromyalgia. Results. Major differences exist between studies in reported disability and in the percentages of women working. Limitations caused by pain, fatigue, decreased muscle strength, and endurance influence work capacity. However, 34-77% of the women work. Individual adjustments in the work situation are reported. When the women find a level that matches their ability, they continue to work and find satisfaction in their work role. Many factors besides degree of impairment or disability influence whether clients with longstanding pain can remain in their work role or return to work after sickness leave. Conclusion. The total life situation, other commitments, type of work tasks, the ability to influence the work situation, and the physical and psychosocial work environment are important factors in determining whether a person can remain in a work role. More knowledge is needed about how to adjust work conditions for people with partial work ability to the benefit of society and the individual.

  • 107.
    Hermansson, Ann-Charlotte
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Department of Health and Society, Division of Preventive and Social Medicine and Public Health Science. Östergötlands Läns Landsting, PC - Psykiatricentrum, FMC - Flyktingmedicinskt centrum.
    Thyberg, M
    Timpka, Toomas
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Department of Health and Society, Division of Preventive and Social Medicine and Public Health Science. Östergötlands Läns Landsting, Centre for Public Health Sciences, Centre for Public Health Sciences.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Survival with pain: an eight-year follow-up of war-wounded refugees.2001In: Medicine, conflict and survival, ISSN 1362-3699, E-ISSN 1743-9396, Vol. 17, no 2, p. 102-111Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to investigate the nature of chronic pain in male war-wounded refugees and to examine the relationship between chronic pain and psychiatric symptoms. A culturally heterogeneous group of 44 war-wounded refugees were investigated during hospitalization, shortly after arrival, and followed up after two years. This study is an additional follow-up after eight years. The data collection methods used were structured interviews and physical examination. The measures of outcome were: Visual Analogue Scale (VAS) grading of pain, clinical categorization of pain into nociceptive or neurogenic, Hopkins Symptom Check List (HSCL-25), Post Traumatic Symptom Scale (PTSS-10). Chronic pain was found in 32 (73%) out of 44 subjects. The pain was purely nociceptive and neurogenic in 53% and 25%, respectively. The frequency of psychiatric symptoms was significantly related to the mean intensity of pain. War-wounded refugees display psychiatric symptoms and chronic pain in a complex pattern. Further research is needed as a basis for pain rehabilitation programmes suitable for this group.

  • 108.
    Holtermann, Andreas
    et al.
    National Research Centre for the Working Environment, Copenhagen, Denmark.
    Grönlund, Christer
    Biomedical Engineering and Informatics, Radiation Sciences, Umeå University, Umeå, Sweden.
    Roeleveld, Karin
    Department of Human Movement Science, Dragvoll, Norwegian University of Science and Technology, Trondheim, Norway.
    Gerdle, Björn
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Sinnescentrum, Pain and Rehabilitation Centre.
    The relation between neuromuscular control and pain intensity in fibromyalgia2011In: JOURNAL OF ELECTROMYOGRAPHY AND KINESIOLOGY, ISSN 1050-6411, Vol. 21, no 3, p. 519-524Article in journal (Refereed)
    Abstract [en]

    Fibromyalgia patients are shown to have a different neuromuscular control (differential activation) than healthy persons. Before clinical trials can be initiated, the relation between differential activations and pain intensity among fibromyalgia patients needs to be investigated. Twenty-seven fibromyalgia patients performed 3 min bilateral shoulder elevations with different loads (0-4 kg) with a high-density surface electromyographical (EMG) grid placed on the upper trapezius. Differential activation was quantified by the power spectral median frequency of the difference in EMG amplitude between the cranial and caudal parts of the upper trapezius. The average duration of the differential activation was described by the inverse of the median frequency of the differential activations. The relation between frequency and duration of differential activations as an average of the 4 loads and pain intensity the same day prior to the experiment was explored by Pearsons correlation coefficients. A strong negative relation between frequency of differential activations and pain intensity (R = -0.67, p andlt; 0.001) and a strong positive association between duration of differential activations and pain intensity (R = 0.66, p andlt; 0.001) were found. The significant association between frequency and duration of differential activations and pain intensity among the fibromyalgia patients indicates a relation between this neuromuscular control pattern and pain intensity. This finding support initiation of clinical trials for investigating effects on pain intensity of modifying differential activations among fibromyalgia patients.

  • 109.
    Hurtig, Ingrid
    et al.
    Linköping University, Department of Medicine and Care, Pharmacology. Linköping University, Faculty of Health Sciences.
    Raak, Ragnhild
    Linköping University, Department of Medicine and Care, Pharmacology. Linköping University, Faculty of Health Sciences.
    Aspegren-Kendall, Sally
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Gerdle, Björn
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Wahren, Lis Karin
    Linköping University, Department of Medicine and Care, Pharmacology. Linköping University, Faculty of Health Sciences.
    Quantitative sensory testing in fibromyalgia patients and in healthy subjects: identification of subgroups2001In: The Clinical Journal of Pain, ISSN 0749-8047, E-ISSN 1536-5409, Vol. 17, no 4, p. 316-322Article in journal (Refereed)
    Abstract [en]

    Objective: To determine perception and pain thresholds in patients with fibromyalgia syndrome and in healthy controls, and to investigate whether patients with fibromyalgia syndrome can be grouped with respect to thermal hyperalgesia and whether these subgroups differ from healthy controls and in clinical appearance. Design: The authors conducted a quasi-experimental clinical study. Subjects: Twenty-nine women patients with fibromyalgia syndrome and 21 healthy pain-free age-matched women participated in the study. Methods: Quantitative sensory testing using a Thermotest instrument was performed on the dorsum of the left hand. Sleep and pain intensity were rated using visual analog scales. Results: Cold and heat pain but not perception thresholds differed significantly between patients with fibromyalgia syndrome and healthy subjects. Based on thermal pain thresholds, two subgroups could be identified in fibromyalgia syndrome using cluster analysis. Conclusion: Patients with fibromyalgia syndrome were subgrouped by quantitative sensory testing (i.e., thermal pain thresholds). Subgroups show clinical differences in pain intensities, number of tender points, and sleep quality. Cold pain threshold was especially linked to these clinical aspects.

  • 110.
    Järemo, Pirjo
    et al.
    Division of Nursing, Department of Neurobiology, Care Sciences and Society, Karolinska University, Huddinge, Sweden.
    Arman, M.
    Division of Nursing, Department of Neurobiology, Care Sciences and Society, Karolinska University, Huddinge, Sweden.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Larsson, Britt
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Gottberg, K.
    Division of Nursing, Department of Neurobiology, Care Sciences and Society, Karolinska University, Huddinge, Sweden.
    Illness beliefs among patients with chronic widespread pain - associations with self-reported health status, anxiety and depressive symptoms and impact of pain2017In: BMC Psychology, E-ISSN 2050-7283, Vol. 5, no 24Article in journal (Refereed)
    Abstract [en]

    Chronic widespread pain (CWP) is a disabling condition associated with a decrease in health. Illness beliefs are individual and are acquired during life. Constraining beliefs may prevent patients from regaining health. Understanding these patients’ illness beliefs may be a way to improve the health care they are offered. The aim of this study was to describe illness beliefs among patients with CWP and associations with self-reported health, anxiety and depressive symptoms, and impact of pain.

  • 111.
    Jöud, Anna
    et al.
    Division of Occupational and Environmental Medicine, Department of Laboratory Medicine Lund, Lund University, Lund, Sweden.
    Björk, Jonas
    Division of Occupational and Environmental Medicine, Department of Laboratory Medicine Lund, Lund University, Lund, Sweden.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Grimby-Ekman, Anna
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Health Metrics, University of Gothenburg, Gothenburg, Sweden..
    Larsson, Britt
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    The association between pain characteristics, pain catastrophizing and health care use: Baseline results from the SWEPAIN cohort2017In: Scandinavian Journal of Pain, ISSN 1877-8860, E-ISSN 1877-8879, Vol. 16, p. 122-128, article id S1877-8860(17)30122-2Article in journal (Refereed)
    Abstract [en]

    BACKGROUND AND AIM: Pain is common and adds to the global burden of disease. However, individuals suffering from pain are a heterogeneous group in terms of pain spreading, intensity and duration. While pain influences overall health care consultation not everyone with pain consult health care. To be able to provide health care matching the patients' needs increased knowledge about what factors determines the decision to consult health care is essential. The aim of this study was to explore the combined importance of pain spreading, intensity, duration and pain catastrophizing for consulting health care.

    METHODS: In this cross-sectional study we used population based survey data from southeast Sweden (SWEPAIN) including 7792 individuals' aged 16-85 reporting pain. We used Modified Poisson regressions to analyse factors of importance related to the decision to consult health care.

    RESULTS: High and moderate pain intensity, as compared to low, increases the probability of consulting health care (High PR=1.7 [95% CI 1.51-1.88], moderate PR=1.2 [1.15-1.41]). Having widespread pain, as compared to localised pain, increased the probability of consulting health (PR=1.2 [1.03-1.36). Pain duration was not associated with increased probability of consulting health care (PR=1.0 CI0.88-1.07). However an interaction (p=0.05) between pain duration and pain catastrophizing beliefs was seen indicating a combined importance of the two when consulting health care.

    CONCLUSION: Our result suggests that pain intensity, pain spreading and pain catastrophizing independently influence the decision to consult health care while there is an interaction effect between pain duration and pain catastrophizing beliefs where the importance of pain catastrophizing believes differ with pain duration; the importance of pain catastrophizing believes differ with pain duration.

    IMPLICATIONS: Treatment and rehabilitation strategies should incorporate this finding in order to meet the individual's needs focusing on the biopsychosocial model within health care focusing not only on actual pain reliefs but also on for example acceptance and behavioural changes.

  • 112.
    Kadi, Fawzi
    et al.
    Örebro Universitet.
    Buskqvist, Lars
    Örebro Universitet.
    Sjöholm, Oskar
    Örebro Universitet.
    Folkesson, Mattias
    Örebro Universitet.
    Karlsson, Stefan
    Umeå Universitet.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Strength, muscular endurance and EMG characteristics of thigh adductors2006In: Isokinetics and exercise science, ISSN 0959-3020, E-ISSN 1878-5913, Vol. 14, no 3, p. 235-239Article in journal (Refereed)
    Abstract [en]

    The assessment of thigh adductors' strength and endurance and electromyographical (EMG) characteristics has received little attention compared to other muscle groups. The aim of this study was to investigate strength, endurance performance and EMG characteristics of m. adductor longus and m. gracilis during concentric thigh adduction in soccer and bandy players. Muscular endurance was evaluated using the torque reduction during 70 repeated maximum concentric adductions at an angular velocity of 60°/s. The EMG mean frequency (MNF) and the signal amplitude ratio (SAR, index for muscles' ability to relax between contractions) were analysed. Peak torque decreased significantly throughout the test and no significant differences were found between the two groups. In both muscles, MNF decreased significantly throughout the test. There were no significant differences in MNF and in SAR variables between soccer and bandy players. In conclusion, the present findings reveal a number of significant aspects related to strength and electromyography of hip adductors. © 2006 - IOS Press and the authors. All rights reserved.

  • 113. Karlsson, JS
    et al.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Akay, M
    Analyzing surface myoelectric signals recorded during isokinetic contractions2001In: IEEE Engineering in Medicine and Biology Magazine, ISSN 0739-5175, E-ISSN 1937-4186, Vol. 20, no 6, p. 97-105Article in journal (Refereed)
  • 114.
    Karlsson, J.S
    et al.
    Umeå.
    Östlund, N
    Umeå.
    Larsson, Barbro
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Lt habit, Lt habilitering.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    An estimation of the influence of force decrease on the mean power spectral frequency shift of the EMG during repetitive maximum dynamic knee extensions2003In: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 13, no 5, p. 461-468Article in journal (Refereed)
    Abstract [en]

    Frequency analysis of myoelectric (ME) signals, using the mean power spectral frequency (MNF), has been widely used to characterize peripheral muscle fatigue during isometric contractions assuming constant force. However, during repetitive isokinetic contractions performed with maximum effort, output (force or torque) will decrease markedly during the initial 40-60 contractions, followed by a phase with little or no change. MNF shows a similar pattern. In situations where there exist a significant relationship between MNF and output, part of the decrease in MNF may per se be related to the decrease in force during dynamic contractions. This study estimated force effects on the MNF shifts during repetitive dynamic knee extensions. Twenty healthy volunteers participated in the study and both surface ME signals (from the right vastus lateralis, vastus medialis, and rectus femoris muscles) and the biomechanical signals (force, position, and velocity) of an isokinetic dynamometer were measured. Two tests were performed: (i) 100 repetitive maximum isokinetic contractions of the right knee extensors, and (ii) five gradually increasing static knee extensions before and after (i). The corresponding ME signal time-frequency representations were calculated using the continuous wavelet transform. Compensation of the MNF variables of the repetitive contractions was performed with respect to the individual MNF-force relation based on an average of five gradually increasing contractions. Whether or not compensation was necessary was based on the shape of the MNF-force relationship. A significant compensation of the MNF was found for the repetitive isokinetic contractions. In conclusion, when investigating maximum dynamic contractions, decreases in MNF can be due to mechanisms similar to those found during sustained static contractions (force-independent component of fatigue) and in some subjects due to a direct effect of the change in force (force-dependent component of fatigue). In order to compare MNF shifts during sustained static and repetitive dynamic contractions it is necessary to estimate the force-dependent component of fatigue of dynamic contractions. Our results are preliminary and have to be confirmed in larger experiments using single dynamic contractions when determining the MNF-force relationship of the unfatigued situation.

  • 115.
    Karlsson, Linn
    et al.
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Ghafouri, Bijar
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center. Region Östergötland, Heart and Medicine Center, Occupational and Environmental Medicine Center.
    Bäckryd, Emmanuel
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Olausson, Patrik
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Ghafouri, Nazdar
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Larsson, Britt
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Intramuscular pain modulatory substances before and after exercise in women with chronic neck pain2015In: European Journal of Pain, ISSN 1090-3801, E-ISSN 1532-2149, Vol. 19, no 8, p. 1075-1085Article in journal (Refereed)
    Abstract [en]

    BackgroundIn peripheral tissue, several substances influence pain and pain modulation. Exercise has been found to decrease pain and improve function for chronic pain conditions, but how and why exercise produces beneficial effects remains unclear. This study investigates whether aspects of pain and concentrations of substances with algesic, analgesic and metabolic functions differ between women with chronic neck shoulder pain (CNSP) and healthy women (CON) and whether changes are found after an exercise intervention for CNSP. MethodsForty-one women with CNSP and 24 CON subjects were included. The participants attended two microdialysis sessions with 4-6 months between the experiments. During this period, the CNSP subjects underwent an exercise intervention. Expression levels of substance P, beta-endorphin, cortisol, glutamate, lactate and pyruvate as well as pain intensity and pressure pain thresholds were analysed. ResultsAt baseline, higher concentrations of glutamate and beta-endorphin and lower concentrations of cortisol in CNSP than CON were found. After exercise, decreased levels of substance P and possibly of glutamate, increased levels of beta-endorphin and cortisol as well as decreased pain intensity and increased pain pressure thresholds were found for CNSP. ConclusionsThe findings at baseline indicated algesic and analgesic alterations in the painful trapezius muscles. The findings for CNSP after the exercise intervention, with changes in peripheral substances and decreased pain intensity and sensitivity, could reflect a long-term physiological effect of the exercise.

  • 116.
    Karlsson, Linn
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Takala, Esa-Pekka
    Work-Related Diseases, Finnish Institute of Occupational Health,.
    Andersson, Gerhard
    Linköping University, Department of Behavioural Sciences and Learning, Psychology. Linköping University, Faculty of Arts and Sciences.
    Larsson, Britt
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Associations between psychological factors and the effect of home-based physical exercise in women with chronic neck and shoulder pain.2016In: SAGE open medicine, E-ISSN 2050-3121, Vol. 4, article id 2050312116668933Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Exercise is often used in the treatment of chronic neck and shoulder muscle pain. It is likely that psychological aspects have an impact on the results of exercise-based treatments.

    OBJECTIVES: (1) To examine the associations between psychological factors and the effect of a home-based physical exercise intervention. (2) To examine differences in psychological factors at baseline between (a) subjects who continued in the trial and those who did not and (b) subjects who completed the intervention and those who did not.

    METHOD: A total of 57 women with chronic neck and shoulder pain were included in a home-based exercise intervention trial. Pain intensity, disability, and psychological factors (anxiety and depression symptoms, catastrophizing, fear-avoidance beliefs, self-efficacy, and pain acceptance) were measured at baseline, after 4-6 months, and after 1 year of exercise. Associations between the psychological factors and changes in pain intensity and disability were analysed, as well as differences in psychological factors at baseline between subjects who continued in and completed the intervention, and those who did not.

    RESULTS: Associations between positive changes in pain intensity and disability were found for low fear-avoidance beliefs and low-pain self-efficacy at baseline. In addition, fear-avoidance beliefs at baseline were higher in the subjects who dropped out of the intervention than in those who continued. Pain acceptance at baseline was higher in the subjects who completed the intervention at the end of the trial.

    CONCLUSION: Particularly, fear-avoidance beliefs and pain self-efficacy should be taken into consideration when implementing home-based physical exercise as treatment for chronic neck pain. In addition, high pain acceptance might improve the adherence to prescribed exercise.

  • 117.
    Karlsson, Linn
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Takala, Esa-Pekka
    Finnish Inst Occupat Hlth, Finland.
    Andersson, Gerhard
    Linköping University, Department of Behavioural Sciences and Learning, Psychology. Linköping University, Faculty of Arts and Sciences. Linköping University, The Swedish Institute for Disability Research. Karolinska Inst, Sweden.
    Larsson, Britt
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Experiences and attitudes about physical activity and exercise in patients with chronic pain: a qualitative interview study2018In: Journal of Pain Research, ISSN 1178-7090, E-ISSN 1178-7090, Vol. 11, p. 133-144Article in journal (Refereed)
    Abstract [en]

    Purpose: The purpose of this study was to describe how patients with chronic pain experience physical activity and exercise (PAamp;E). Method: This qualitative interview study included 16 women and two men suffering from chronic pain and referred to a multimodal pain rehabilitation program. Semi-structured interviews were conducted and qualitative content analysis was used to analyze the interviews. Results: One main theme emerged: "To overcome obstacles and to seize opportunities to be physically active despite chronic pain." This main theme was abstracted from five themes: "Valuing a life with physical activity," "Physical activity and exercise - before and after pain," "A struggle - difficulties and challenges," "The enabling of physical activity," and "In need of continuous and active support." Conclusion: Although these participants valued PAamp;E, they seldom achieved desirable levels, and performance of PAamp;E was undermined by difficulties and failure. The discrepancy between the intention to perform physical activity and the physical activity accomplished could be related to motivation, self-efficacy, and action control. The participants desired high-quality interaction with healthcare providers. The findings can be applied to chronic pain rehabilitation that uses PAamp;E as treatment.

  • 118.
    Karlsson, Linn
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Takala, Esa-Pekka
    Finnish Institute Occupat Heatlh, Finland .
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Larsson, Britt
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Evaluation of pain and function after two home exercise programs in a clinical trial on women with chronic neck pain - with special emphasises on completers and responders2014In: BMC Musculoskeletal Disorders, ISSN 1471-2474, E-ISSN 1471-2474, Vol. 15, no 6Article in journal (Refereed)
    Abstract [en]

    Background: Different types of exercises can help manage chronic neck pain. Supervised exercise interventions are widely used, but these protocols require substantial resources. The aim of this trial, which focused on adherence, was to evaluate two home exercise interventions. Methods: This parallel group randomized controlled trial included 57 women randomly allocated into two groups - a strength training group (STRENGTH, 34 subjects) and a stretching group (STRETCH, 23 subjects). The interventions focused on the neck and shoulder muscles and lasted for 12 months. The STRENGTH group performed weight training and ended each session with stretching exercises. These stretching exercises constituted the entirety of the STRETCH groups training session. Both groups were instructed to exercise three times per week. All the participants kept an exercise diary. In addition, all participants were offered support via phone and e-mail. The primary outcomes were pain intensity and function. The trial included a four-to six-month and a twelve-month follow-up. A completer in this study exercised at least 1,5 times per week during eight unbroken weeks. A responder in this study reported clinically significant improvements on pain and function. The statistical analyses used the Mann Whitney U-test, Wilcoxon signed-rank test, and X-2 test. Results: At four-to six-months, the numbers of completers were 19 in the STRENGTH group and 17 in the STRETCH group. At twelve months, the corresponding numbers were 11 (STRENGTH) and 10 (STRETCH). At four-to six-months, the proportions of subjects reporting clinically important changes (STRENGTH and STRETCH) were for neck pain: 47% and 41%, shoulder pain: 47% and 47%, function: 37% and 29%. At twelve months, the corresponding numbers were for neck pain: 45% and 40%, shoulder pain: 55% and 50%, function: 55% and 20%. Conclusions: No differences in the two primary outcomes between the two interventions were found, a finding that may be due to the insufficient statistical power of the study. Both interventions based on home exercises improved the two primary outcomes, but the adherences were relatively low. Future studies should investigate ways to improve adherence to home exercise treatments.

  • 119. Karlsson, Stefan
    et al.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Mean frequency and signal amplitude of the surface EMG of the quadriceps muscles increase with increasing torque - A study using the continuous wavelet transform2001In: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 11, no 2, p. 131-140Article in journal (Refereed)
    Abstract [en]

    The continuous wavelet transform (CWT), a time-frequency method, was used when calculating mean frequency of the power spectrum (MNF) and signal amplitude (RMS) of the surface EMG to investigate their relationships to force during a gradually increasing knee extension (ramp). Based upon the CWT, MNF was redefined to include time dependence on the EMG signal frequency contents, the short-time MNF (STMNF). Surface EMG was recorded from vastus lateralis, rectus femoris and vastus medialis in 21 clinically healthy subjects during a brief, gradually increasing contraction up to 100% of a maximum voluntary contraction (MVC), with a duration of approximately 10 s. The relationships between the EMG variables and force using linear regression were determined for each subject. For vastus lateralis, we also investigated if certain aspects of the muscle morphology (i.e., proportions and areas of different fibre types) influenced the EMG-force relationship.For the majority of subjects (17-18 out of 21 subjects) there were significant positive correlations between STMNF and force in the three muscles. No sex differences were found in intercepts or regression coefficients of STMNF. The muscle morphology had a significant influence on the STMNF-force intercept and the regression coefficient. Positive and highly significant linear correlations between RMS and force were found for all subjects and all three muscles.In conclusion, time frequency methods can be applied when investigating EMG during brief contractions associated with non-stationarity. In a great majority of the subjects, and in the three muscles, significant linear force dependencies were found for STMNF. Thus, when evaluating muscle fatigue, e.g., in ergonomic situations, it is important to consider the force level as one factor that can influence the results. Morphological variables (fibre proportions and fibre areas) influenced the STMNF-force relationship in vastus lateralis. Copyright

  • 120.
    Kosek, Eva
    et al.
    Karolinska University Hospital, Sweden; Lowenstromska Hospital, Sweden.
    Martinsen, Sofia
    Karolinska University Hospital, Sweden.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Mannerkorpi, Kaisa
    University of Gothenburg, Sweden.
    Löfgren, Monika
    Danderyd Hospital, Sweden.
    Bileviciute-Ljungar, Indre
    Danderyd Hospital, Sweden.
    Fransson, Peter
    Karolinska University Hospital, Sweden.
    Schalling, Martin
    Karolinska Institute, Sweden.
    Ingvar, Martin
    Karolinska University Hospital, Sweden.
    Ernberg, Malin
    Karolinska Institute, Sweden.
    Jensen, Karin B.
    Karolinska University Hospital, Sweden.
    The translocator protein gene is associated with symptom severity and cerebral pain processing in fibromyalgia2016In: Brain, behavior, and immunity, ISSN 0889-1591, E-ISSN 1090-2139, Vol. 58, p. 218-227Article in journal (Refereed)
    Abstract [en]

    The translocator protein (TSPO) is upregulated during glia activation in chronic pain patients. TSPO constitutes the rate-limiting step in neurosteroid synthesis, thus modulating synaptic transmission. Related serotonergic mechanisms influence if pro- or anti-nociceptive neurosteroids are produced. This study investigated the effects of a functional genetic polymorphism regulating the binding affinity to the TSPO, thus affecting symptom severity and cerebral pain processing in fibromyalgia patients. Gene-to-gene interactions with a functional polymorphism of the serotonin transporter gene were assessed. Fibromyalgia patients (n = 126) were genotyped regarding the polymorphisms of the TSPO (rs6971) and the serotonin transporter (5-HTTLPR/rs25531). Functional magnetic resonance imaging (n = 24) was used to study brain activation during individually calibrated pressure pain. Compared to mixed/low TSPO affinity binders, the high TSPO affinity binders rated more severe pain (p = 0.016) and fibromyalgia symptoms (p = 0.02). A significant interaction was found between the TSPO and the serotonin transporter polymorphisms regarding pain severity (p amp;lt; 0.0001). Functional connectivity analyses revealed that the TSPO high affinity binding group had more pronounced pain-evoked functional connectivity in the right frontoparietal network, between the dorsolateral prefrontal area and the parietal cortex. In conclusion, fibromyalgia patients with the TSPO high affinity binding genotype reported a higher pain intensity and more severe fibromyalgia symptoms compared to mixed/low affinity binders, and this was modulated by interaction with the serotonin transporter gene. To our knowledge this is the first evidence of functional genetic polymorphisms affecting pain severity in FM and our findings are in line with proposed glia-related mechanisms. Furthermore, the functional magnetic resonance findings indicated an effect of translocator protein on the affective-motivational components of pain perception. (C) 2016 The Authors. Published by Elsevier Inc.

  • 121.
    Kvist, Joanna
    et al.
    Linköping University, Department of Medical and Health Sciences, Sports Medicine . Linköping University, Department of Neuroscience and Locomotion. Linköping University, Faculty of Health Sciences.
    Karlberg, Christian
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine. Linköping University, Department of Neuroscience and Locomotion. Linköping University, Faculty of Health Sciences.
    Gerdle, Björn
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Gillquist, Jan
    Linköping University, Department of Medical and Health Sciences, Sports Medicine . Linköping University, Department of Neuroscience and Locomotion. Linköping University, Faculty of Health Sciences.
    Anterior tibial translation during different isokinetic quadriceps torque in anterior cruciate ligament deficient and nonimpaired individuals2001In: Journal of Orthopaedic and Sports Physical Therapy, ISSN 0190-6011, E-ISSN 1938-1344, Vol. 31, no 1, p. 4-15Article in journal (Refereed)
    Abstract [en]

    Study Design: Factorial quasi-experimental design.

    Objectives: To quantify the effect of different levels of isokinetic concentric and eccentric knee extensor torques on the anterior tibial translation in subjects with anterior cruciate ligament (ACL) deficiency. Electromyogram (EMG) activity of 4 leg muscles was recorded in order to detect any co-activation of extensors and flexors.

    Background: The rehabilitation after an ACL injury is of importance for the functional outcome of the patient. In order to construct a rehabilitation program after that injury, it is important to understand the in vivo relationships between muscle force and tibial translation.

    Methods and Measures: Twelve patients with unilateral ACL injury and 11 uninjured volunteers performed 36 repetitions of a quadriceps contraction at different isokinetic concentric and eccentric torque levels, on a KinCom machine (60°•s-1), with simultaneous recordings of tibial translation (CA-4000) and EMG activity from quadriceps and hamstrings muscles. Tibial translations and EMG levels were normalized to the maximum of each subject.

    Results: The individual anterior tibial translation increased with increased quadriceps torque in a similar manner in both quadriceps contraction modes in all legs tested. During concentric mode, translation was similar in all groups, but during eccentric mode, the mean translation was 38% larger in the ACL injured knees. No quadriceps-hamstrings co-activation occurred in any test or group.

    Conclusions: An ACL deficient knee can limit the translation within a normal space during concentric muscle activity but not during eccentric activity. That limitation depends on other mechanisms than hamstrings co-activation.

  • 122.
    Larsson, Anette
    et al.
    Univ Gothenburg, Sweden.
    Palstam, Annie
    Univ Gothenburg, Sweden.
    Bjersing, Jan
    Sahlgrens Univ Hosp, Sweden.
    Lofgren, Monika
    Karolinska Inst, Sweden; Danderyd Hosp, Sweden.
    Ernberg, Malin
    Karolinska Inst, Sweden; SCON, Sweden.
    Kosek, Eva
    Karolinska Inst, Sweden; Stockholm Spine Ctr, Sweden.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Mannerkorpi, Kaisa
    Univ Gothenburg, Sweden; Sahlgrens Univ Hosp, Sweden.
    Controlled, cross-sectional, multi-center study of physical capacity and associated factors in women with fibromyalgia2018In: BMC Musculoskeletal Disorders, ISSN 1471-2474, E-ISSN 1471-2474, Vol. 19, article id 121Article in journal (Refereed)
    Abstract [en]

    Background: Health and physical capacity are commonly associated with disease, age, and socioeconomic factors. The primary objective of this study was to investigate the degree to which physical capacity, defined as muscle strength and walking ability, is decreased in women with fibromyalgia (FM), as compared to healthy women, who are matched for age and level of education. The secondary aim was to investigate whether muscle strength and walking ability are associated with age, symptom duration, activity limitations and, Body Mass Index (BMI) in women with FM and control subjects. Methods: This controlled, cross-sectional, multi-center study comprised 118 women with FM and 93 age-and education-level-matched healthy women. The outcome measures were isometric knee-extension force, isometric elbow-flexion force, isometric hand-grip force, and walking ability. Differences between the groups were calculated, and for the women with FM analyses of correlations between the measures of physical capacity and variables were performed. Results: The women with FM showed 20% (p amp;lt; 0.001) lower isometric knee-extension force, 36% (p amp;lt; 0.001) lower isometric elbow-flexion force, 34% (p amp;lt; 0.001) lower isometric hand-grip force, and 16% lower walking ability (p amp;lt; 0.001), as compared to the healthy controls. All measures of muscle strength in women with FM showed significant weak to moderate relationship to symptom duration (r(s) = -0.23-0.32) and walking ability (r(s) = 0.25-0.36). Isometric knee-extension force correlated with activity limitations, as measured using the SF-36 Physical function subscale (r(s)= 0.23, p = 0.011). Conclusions: Physical capacity was considerably decreased in the women with FM, as compared to the age-and education-level-matched control group. All measures of physical capacity showed a significant association with symptom duration. Knee-extension force and walking ability were significantly associated with activity limitations, age, and BMI. It seems important to address this problem and to target interventions to prevent decline in muscle strength. Assessments of muscle strength and walking ability are easy to administer and should be routinely carried out in the clinical setting for women with FM.

  • 123.
    Larsson, Anette
    et al.
    University of Gothenburg, Sweden.
    Palstam, Annie
    University of Gothenburg, Sweden.
    Loefgren, Monika
    Karolinska Institute, Sweden; Danderyd Hospital, Sweden.
    Ernberg, Malin
    Karolinska Institute, Sweden; SCON, Sweden.
    Bjersing, Jan
    Sahlgrens University Hospital, Sweden.
    Bileviciute-Ljungar, Indre
    Karolinska Institute, Sweden; Danderyd Hospital, Sweden.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Kosek, Eva
    Karolinska Institute, Sweden; Stockholm Spine Centre, Sweden.
    Mannerkorpi, Kaisa
    University of Gothenburg, Sweden; University of Gothenburg, Sweden; Sahlgrens University Hospital, Sweden.
    PAIN AND FEAR AVOIDANCE PARTIALLY MEDIATE CHANGE IN MUSCLE STRENGTH DURING RESISTANCE EXERCISE IN WOMEN WITH FIBROMYALGIA2017In: Journal of Rehabilitation Medicine, ISSN 1650-1977, E-ISSN 1651-2081, Vol. 49, no 9, p. 744-750Article in journal (Refereed)
    Abstract [en]

    Objectives: Resistance exercise results in health benefits in fibromyalgia. The aim of this study was to determine the factors that mediate change in muscle strength in women with fibromyalgia as a result of resistance exercise. Methods: Sixty-seven women with fibromyalgia (age range 25-64 years) were included. Tests of muscle strength and questionnaires related to pain, fear avoidance and physical activity were carried out. Multivariable stepwise regression was used to analyse explanatory factors for change and predictors for final values of knee-extension force, elbow-flexion force and hand-grip force. Results: Change in knee-extension force was explained by fear avoidance beliefs about physical activity at baseline, together with change in pain intensity, knee-extension force at baseline, age and body mass index (BMI) (R-2= 0.40, p = 0.013). Change in elbow-flexion force was explained by pain intensity at baseline, together with baseline fear avoidance beliefs about physical activity, BMI and elbow-flexion force at baseline (R-2 = 0.32, p = 0.043). Change in hand-grip force was explained by hand-grip force at baseline, change in pain intensity and baseline fear avoidance (R-2 = 0.37, p = 0.009). Final muscle strength was predicted by the same variables as change, except pain. Conclusion: Pain and fear avoidance are important factors to consider in rehabilitation using resistance exercise for women with fibromyalgia.

  • 124.
    Larsson, Anette
    et al.
    University of Gothenburg, Sweden; University of Gothenburg, Sweden.
    Palstam, Annie
    University of Gothenburg, Sweden; University of Gothenburg, Sweden.
    Lofgren, Monika
    Karolinska Institute, Sweden.
    Ernberg, Malin
    Karolinska Institute, Sweden.
    Bjersing, Jan
    Sahlgrens University Hospital, Sweden.
    Bileviciute-Ljungar, Indre
    Karolinska Institute, Sweden.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Kosek, Eva
    Karolinska Institute, Sweden.
    Mannerkorpi, Kaisa
    University of Gothenburg, Sweden; University of Gothenburg, Sweden; University of Gothenburg, Sweden.
    Resistance exercise improves muscle strength, health status and pain intensity in fibromyalgia: a randomized controlled trial2015In: Arthritis Research & Therapy, ISSN 1478-6354, E-ISSN 1478-6362, Vol. 17, no 161Article in journal (Refereed)
    Abstract [en]

    Introduction: Fibromyalgia (FM) is characterized by persistent widespread pain, increased pain sensitivity and tenderness. Muscle strength in women with FM is reduced compared to healthy women. The aim of this study was to examine the effects of a progressive resistance exercise program on muscle strength, health status, and current pain intensity in women with FM. Methods: A total of 130 women with FM (age 22-64 years, symptom duration 0-35 years) were included in this assessor-blinded randomized controlled multi-center trial examining the effects of progressive resistance group exercise compared with an active control group. A person-centred model of exercise was used to support the participants self-confidence for management of exercise because of known risks of activity-induced pain in FM. The intervention was performed twice a week for 15 weeks and was supervised by experienced physiotherapists. Primary outcome measure was isometric knee-extension force (Steve Strong (R)), secondary outcome measures were health status (FIQ total score), current pain intensity (VAS), 6MWT, isometric elbow-flexion force, hand-grip force, health related quality of life, pain disability, pain acceptance, fear avoidance beliefs, and patient global impression of change (PGIC). Outcomes were assessed at baseline and immediately after the intervention. Long-term follow up comprised the self-reported questionnaires only and was conducted after 13-18 months. Between-group and within-group differences were calculated using non-parametric statistics. Results: Significant improvements were found for isometric knee-extension force (p = 0.010), health status (p = 0.038), current pain intensity (p = 0.033), 6MWT (p = 0.003), isometric elbow flexion force (p = 0.02), pain disability (p = 0.005), and pain acceptance (p = 0.043) in the resistance exercise group (n = 56) when compared to the control group (n = 49). PGIC differed significantly (p = 0.001) in favor of the resistance exercise group at post-treatment examinations. No significant differences between the resistance exercise group and the active control group were found regarding change in self-reported questionnaires from baseline to 13-18 months. Conclusions: Person-centered progressive resistance exercise was found to be a feasible mode of exercise for women with FM, improving muscle strength, health status, and current pain intensity when assessed immediately after the intervention.

  • 125.
    Larsson, B.
    et al.
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Sinnescentrum, Pain and Rehabilitation Centre.
    Björk, J.
    Skåne University Hospital, Sweden .
    Börsbo, Björn
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Sinnescentrum, Pain and Rehabilitation Centre.
    A systematic review of risk factors associated with transitioning from regional musculoskeletal pain to chronic widespread pain2012In: European Journal of Pain, ISSN 1090-3801, E-ISSN 1532-2149, Vol. 16, no 8, p. 1084-1093Article, review/survey (Refereed)
    Abstract [en]

    Chronic widespread pain has limited treatment options and is associated with pronounced negative individual and socioeconomic consequences. Patients with local or regional pain may be at a risk for developing chronic widespread pain. Knowledge of such risk factors can help prevent chronic widespread pain. This study systematically reviews the literature that examines risk factors associated with developing chronic widespread after developing chronic regional pain. We conducted a three-step database search in Medline. Four articles from the authors files formed a core set of articles that were used to validate the search strategy. We conducted a systematic quality assessment of the included studies. Based on risk estimations reported in six prospective population-based studies and one retrospective study on pain, this study identified five risk factors: female sex, higher age, family history of pain, depressed mode and pain sites at baseline. As only a few studies were recovered, the impact of these factors is unclear. Spreading of pain from local or regional pain to widespread pain occurs in a large proportion of the general population. Few studies have addressed similar risk factors and the few risk factors associated with the transition from chronic regional pain to chronic widespread pain are inconsistent. Studies that focus on this transition have included few subjects and few possible risk factors. Future studies should explore more possible risk factors.

  • 126. Larsson, B
    et al.
    Björk, J
    Elert, Jessica
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine.
    Lindman, R
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Fibre type proportion and fibre size in trapezius muscle biopsies from cleaners with and without myalgia and its correlation with ragged red fibres, cytochrome-c-oxidase-negative fibres, biomechanical output perception of fatigue, and surface electromyograghy during repetitive forward flexions2001In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 84, p. 492-502Article in journal (Refereed)
  • 127.
    Larsson, Barbro
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine/Pain Clinic.
    Björk, J.
    Elert, Jessica
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Department of Health and Society, Division of Physiotherapy.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine/Pain Clinic. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Mechanical performance and electromyography during repeated maximal isokinetic shoulder forward flexions in female cleaners with and without myalgia of the trapezius muscle and in healthy controls.2000In: European Journal of Applied Physiology and Occupational Physiology, ISSN 0301-5548, E-ISSN 1432-1025, Vol. 83, p. 257-267Article in journal (Refereed)
  • 128.
    Larsson, Barbro
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine/Pain Clinic.
    Björk, J
    Henriksson, Karl-Gösta
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine/Pain Clinic. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine/Pain Clinic. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Lindman, R.
    The prevalences of cytochrome c oxidase negative and superpositive fibres and ragged-red fibres in the trapezius muscle of female cleaners with and without myalgia and of female healthy controls2000In: Pain, ISSN 0304-3959, E-ISSN 1872-6623, Vol. 84, no 2-3, p. 379-387Article in journal (Refereed)
    Abstract [en]

    The association of cytochrome c oxidase negative fibres (COX-negative) and ragged-red fibres (RR-fibres) with work related trapezius myalgia has been proposed. Hitherto studies have been small or without control groups. The aim of the present study was to investigate the prevalences of RR-fibres and COX-negative fibres in female cleaners with (n=25) and without (n=23) trapezius myalgia and in clinically healthy female teachers (n=21). The cleaners did mainly floor cleaning requiring monotonous loading on the trapezius muscle. A questionnaire covering background data and aspects of pain (prevalence, duration, intensity and influence on daily living) was answered. Biopsies were obtained from the trapezius muscle by an open surgical technique. The three groups did not differ in prevalence of COX-negative or COX-superpositive (i.e. type-I fibres with extremely strong brownish reaction in both the COX and SDH/COX stainings) fibres. The prevalence of COX-negative fibres was age dependent. Two subgroups of RR-fibres were present when stained for COX, COX-negative (73%) and COX-superpositive (26%) fibres. Forty-two percent of the COX-negative fibres were RR-fibres and 79% of the COX-superpositive were RR-fibres. A significantly (P=0.002) higher proportion of the COX-superpositive fibres in the cleaners were RR-fibres compared to the teachers. Multivariate regression analysis revealed that age, occupation as cleaner and a tender point in the trapezius were significantly associated with increased prevalences of RR-fibres, a cleaner with a tender point had a 4.35 higher prevalence of RR-fibres compared to a teacher without a tender point. No correlations between other pain related variables and prevalence of RR-fibres were noted. In conclusion, RR-fibres but not COX-negative or COX-superpositive fibres were correlated with cleaning work tasks and with a tender point in the trapezius.

  • 129.
    Larsson, Barbro
    et al.
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Kadi, Fawzi
    Department of Physical Education and Health, Örebro University, Örebro, Sweden.
    Lindvall, Björn
    Linköping University, Department of Neuroscience and Locomotion, Neurology. Linköping University, Faculty of Health Sciences.
    Gerdle, Björn
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Pain and Occupational Centre, Pain and Rehabilitation Centre. Linköping University, Faculty of Health Sciences.
    Surface electromyography and peak torque of repetitive maximum isokinetic plantar flexions in relation to aspects of muscle morphology2006In: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 16, no 3, p. 281-290Article in journal (Refereed)
    Abstract [en]

    This study investigates the relationships between surface electromyography (EMG [Mean frequency of the power spectrum (MNF)]) and peak torque variables obtained during 100 maximum concentric plantar flexions with the right limb at 60° s−1 and different muscle morphological variables. Surface EMG was recorded from the right gastrocnemius lateralis and muscle biopsies were taken from the same site as the EMG electrodes were positioned. Muscle fibre area and fibre type composition were determined on serial muscle cross sections using both histochemistry (myofibrillar adenosine triphosphatase) and immunohistochemistry (monoclonal antibodies against specific myosin heavy chain isoforms). Forty-three female and nine male students participated in the study. Gastrocnemius lateralis contained predominantly type I fibres (50%) and type IIA fibres (40%) in both sexes and large individual differences were found. Principal component analysis (PCA) was used for the intercorrelation analyses, and projection to latent structures (PLS) was used for the multivariate regression analysis. MNF correlated positively with different fibre areas and with the proportion of type I fibres. Fibre areas and sex were the most important factors in the regression of maximum peak torque. High proportion of type I fibres and sex were the most important regressors of peak torque endurance normalised for lean body mass.

    More studies are needed to understand the complex interrelationships between intrinsic muscle properties and the frequency content of the surface EMG before theoretical models can be formulated that incorporate both fibre areas and fibre type proportions.

  • 130.
    Larsson, Barbro
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Karlberg, Christian
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine.
    Elert, Jessica
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Reproducibility of surface EMG during dynamic shoulder forward flexions: A study of clinically healthy subjects.1999In: Clinical Physiology, ISSN 0144-5979, E-ISSN 1365-2281, Vol. 19, p. 433-439Article in journal (Refereed)
  • 131.
    Larsson, Barbro
    et al.
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Karlsson, Stefan
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Eriksson, Magnus
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Gerdle, Björn
    Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre. Linköping University, Faculty of Health Sciences.
    Test–retest reliability of EMG and peak torque during repetitive maximum concentric knee extensions2003In: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 13, no 3, p. 281-287Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to investigate the reliability of peak torque and surface electromyography (EMG) variable’s root mean square (RMS) and mean frequency (MNF) during an endurance test consisting of repetitive maximum concentric knee extensions. Muscle fatigue has been quantified in several ways, and in isokinetic testing it is based on a set of repetitive contractions. To assess test–retest reliability, two sets of 100 dynamic maximum concentric knee extensions were performed using an isokinetic dynamometer. The two series were separated by 7–8 days. The subjects relaxed during the passive flexion phase. Twenty (10 men and 10 women) clinically healthy subjects volunteered.

    Peak torque and EMG from rectus femoris, vastus medialis, vastus lateralis and biceps femoris were recorded. RMS and MNF were calculated from the EMG signal. The reliability was calculated with intraclass correlation coefficient ICC (1.1) and standard error of measurements (SEM). The reliability of peak torque was good (ICC=0.93) and SEM showed low values. ICC was good for absolute RMS of rectus femoris (ICC≥0.80), vastus medialis (ICC≥0.88) and vastus lateralis (ICC≥0.82) and MNF of rectus femoris (ICC≥0.82) and vastus medialis (ICC≥0.83). Peak torque, and MNF and RMS of rectus femoris and vastus medialis are reliable variables obtained from an isokinetic endurance test of the knee extensors.

  • 132.
    Larsson, Barbro
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Karlsson, Stefan
    Department of Biomedical Engineering and Informatics, Umeå University Hospital, Umeå, Sweden.
    Gerdle, Björn
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre. Linköping University, Faculty of Health Sciences.
    Muscle performance during maximum repeated knee extensions in children with hemiplegic cerebral palsy2008In: Isokinetics and exercise science, ISSN 0959-3020, E-ISSN 1878-5913, Vol. 16, no 4, p. 221-230Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to compare isokinetic muscle performance of the knee extensors including surface EMG during repetitive maximum contractions between children with hemiplegic CP and healthy controls. A group of children with hemiplegic cerebral palsy (CP) (16 boys and eight girls; mean age 11 years with SD 2; range 7 to 15 years) and a control group (14 boys and eight girls; mean age 10 years with SD 2; range 7 to 15 years) participated. The relationships between maximum peak torque and the surface electromyography (EMG) variable root mean square (RMS) were obtained during 100 concentric knee extensions at 90°/s. Surface EMG was recorded from rectus femoris, vastus lateralis, and biceps femoris. The children with CP were also tested using Gross Motor Function Measure (GMFM). There were no differences between the groups in muscle endurance for the younger children. The results indicated that the children with CP had less strength enhancement in the hemiplegic leg during puberty. Peak torque correlated with GMFM and with RMS in rectus femoris and vastus lateralis. Co-activation was found in biceps femoris, but it did not affect muscle strength.

  • 133.
    Larsson, Barbro
    et al.
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Månsson, Bjarne
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Karlberg, Christian
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Syvertsson, Peter
    Östergötlands Läns Landsting, Pain and Occupational Centre, Pain and Rehabilitation Centre. Linköping University, Faculty of Health Sciences.
    Elert, Jessica
    Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences.
    Gerdle, Björn
    Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre. Linköping University, Faculty of Health Sciences.
    Reproducibility of surface EMG variables and peak torque during three sets of ten dynamic contractions1999In: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 9, no 5, p. 351-357Article in journal (Refereed)
    Abstract [en]

    The interpretation of the electromyogram (EMG) of dynamic contractions might be difficult because the movement per se introduces additional factors that could affect its characteristics. There is a lack of studies concerning the reproducibility of surface EMG registrations during dynamic contractions. The aim was to investigate the during-the-day reproducibility (using intra-class correlation; ICC) of the peak torque (PT) and the EMG variables (without removing the electrodes) of dynamic contractions. Ten healthy subjects performed three sets of 10 dynamic maximum right-knee extensions with a one-hour interval in between, using an isokinetic dynamometer and the PT was determined. EMG signals were recorded from the right vastus lateralis, rectus femoris and vastus medialis muscles using surface electrodes and the mean frequency of the power spectrum (MNF [Hz]) and the signal amplitude (RMS [μV]), were computed. The ability to relax in-between the maximum extensions was calculated as a ratio of the RMS during the passive flexion phase and the RMS during the active extension phase of each contraction cycle: the signal amplitude ratio (SAR).

    Both PT (ICC=0.99) and RMS (ICC=0.83–0.98) had good reproducibility. The reproducibility of MNF was good for all muscles when the mean of contraction nos.: 1–10 was used. Vastus lateralis had the highest ICC among the three muscles. The reproducibility of SAR was generally poor (ICC<0.60). The present study showed good reproducibility for common EMG variables (MNF and RMS) obtained during maximum isokinetic contractions.

  • 134. Larsson, Britt
    et al.
    Andersen, Jesper L
    Kadi, Fawzi
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Myosin heavy chain isoforms influence surface EMG parameters: A study of the trapezius muscle in cleaners with and without myalgia and in healthy teachers2002In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 87, no 6, p. 481-488Article in journal (Refereed)
    Abstract [en]

    The present study had two aims: (1) to investigate potential differences in proportion of myosin heavy chain isoforms in the trapezius muscle between female cleaners with and without trapezius myalgia and healthy teachers, and (2) to elucidate if myosin heavy chain composition and surface electromyogram (EMG) during an isokinetic endurance test of shoulder flexors are significantly related. The subjects were divided into three groups: (1) 25 female cleaners with diagnosed work-related trapezius myalgia, (2) 25 female cleaners without work-related trapezius myalgia, (3) a control group of 21 healthy female teachers who were not exposed to repetitive or static muscle work. All subjects performed a test involving 150 forward flexions using an isokinetic dynamometer. During the test surface EMG was recorded from the trapezius muscle. Muscle samples were obtained from the descending part of the trapezius muscle. The fibre type area percentage based on ATPase staining and the proportions of different MHC isoforms as determined by gel electrophoresis. The trapezius was dominated by MHC I (71%), followed by MHC IIA (22-24%), and MHC IIX (5-7%), no significant differences between the three groups of subjects were found. The proportion of MHC I correlated negatively with MHC IIA (r=-0.78, P<0.001) and MHC IIX (r= -0.53, P<0.001). Significant correlations existed between the proportion of the MHC isoforms and the corresponding proportion of the fibre type area, 27-45% of the variance was explained. The multivariate analysis of the three groups of subjects revealed that MHC variables showed intercorrelations with EMG (both amplitude and frequency variables). However, the directions of the relationships differed among the three groups, the cleaners with myalgia and the teachers showed the greatest similarities in patterns. Intrinsic muscle properties appear to influence the frequency content of the EMG, which is in contrast to some of the theoretical models of the EMG. Our data could suggest that monotonous work such as professional cleaning can change the relationships between muscle structure and the frequency content of the EMG.

  • 135. Larsson, Britt
    et al.
    Björk, Jonas
    Kadi, Fawzi
    Lindman, Rolf
    Gerdle, Björn
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Neuroscience and Locomotion, Rehabilitation Medicine. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Blood supply and oxidative metabolism in muscle biopsies of female cleaners with and without myalgia2004In: The Clinical Journal of Pain, ISSN 0749-8047, E-ISSN 1536-5409, Vol. 20, no 6, p. 440-446Article in journal (Refereed)
    Abstract [en]

    Objectives: Pathomechanisms of work-related myalgia are poorly understood. Myalgia is thought to be caused by excitation of nociceptors present in the muscular tissue but not in the muscle fiber itself. Muscle contraction in combination with hypoxia is known to excite nociceptors. Morphologic analysis can contribute to the knowledge of the excitation of nociceptors. This study thoroughly examines the morphology of the trapezius muscle's capillary supply and signs of disturbed oxidative metabolism to understand their role in work-related myalgia. Methods: Surgical trapezius muscle biopsies were obtained from 25 female cleaners with long-standing work-related myalgia, 25 female cleaners without trapezius myalgia, and 21 healthy teachers. Enzyme and immunohistochemical stainings were performed to highlight fibers with aberrant intermyofibrillar patterns, indicating a disturbed oxidative metabolism (also known as moth-eaten fibers) and a disturbed capillary supply of different fibers. Results: A significantly lower number of capillaries per fiber area in cleaners suffering from myalgia compared with cleaners without trapezius myalgia was found. Moth-eaten fibers were found in the 3 groups, but these fibers were significantly more prevalent in the groups of cleaners than in the healthy teacher group. Conclusion: This work indicates that the capillary supply of trapezius is affected in work-related trapezius myalgia. More studies are needed to understand possible mechanisms that would explain the occurrence of moth-eaten fibers.

  • 136.
    Larsson, Britt
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Dragioti, Elena
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Bjork, Jonas
    Lund Univ, Sweden; Skane Univ Hosp Lund, Sweden.
    Positive psychological well-being predicts lower severe pain in the general population: a 2-year follow-up study of the SwePain cohort2019In: Annals of General Psychiatry, ISSN 1744-859X, E-ISSN 1744-859X, Vol. 18, article id 8Article in journal (Refereed)
    Abstract [en]

    BackgroundPositive psychology indicators like well-being and life satisfaction may play a pivotal role in pain-related outcomes. In this study, we aimed to examine the prospective associations of positive well-being and life satisfaction with pain severity.Methods and SubjectsThis longitudinal study, with a follow-up of 2years, included 9361 participants (4266 males, 5095 females; mean age: 52.5years; SD: 17.5) without and with chronic pain (CP) at baseline. All analyses were stratified by the two sub-cohortsparticipants without CP (sub-cohort 1) and participants with CP (sub-cohort 2) at baseline. The predictive associations, assessed using ordinal regression in a Generalized Linear Model, were adjusted for baseline potential confounders and reported as odds ratios (ORs) with corresponding 95% confidence intervals (CIs).ResultsAfter adjustments, in sub-cohort 1 positive well-being at baseline was associated with lower severe pain at follow-up compared to participants with severe distress (OR: 0.64; 95% CI 0.49-0.84; pamp;lt;0.001). In sub-cohort 2, both positive well-being and life satisfaction at baseline were associated with lower severe pain at follow-up compared to participants with severe distress and not satisfied with life (OR: 0.80; 95% CI 0.65-0.98; p=0.031 and OR: 0.82; 95% CI 0.69-0.96; p=0.014, respectively).ConclusionsPositive well-being is predictive of lower pain severity both among participants without and with CP at baseline, whereas life satisfaction was found predictive of lower pain severity only for subjects with CP. Future research should emphasize implementing treatments associated with promoting and maintaining positive well-being and life satisfaction in patients who suffer from chronic pain and in risk populations.

  • 137.
    Larsson, Britt
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Dragioti, Elena
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Grimby-Ekman, Anna
    Health Metrics, University of Gothenburg, Gothenburg, Sweden.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Ejork, Jonas
    Division of Occupational and Environmental Medicine, Lund University, Lund, Sweden.
    Predictors of chronic pain intensity, spread, and sensitivity in the general population: A two-year follow-up study from the SWEPAIN cohort2019In: Journal of Rehabilitation Medicine, ISSN 1650-1977, E-ISSN 1651-2081, Vol. 51, no 3, p. 183-192Article in journal (Refereed)
    Abstract [en]

    Objective: To determine whether the intensity, spread and sensitivity of chronic pain can be predicted using demographic features, socioeconomic conditions and comorbidities.

    Design: A longitudinal study design was employed. Data was collected at baseline and at 2-year follow-up. Setting: General population in south-eastern Sweden.

    Subjects: A representative stratified random sample of 34,000 individuals, between 18 and 85 years of age, selected from a sampling frame of 404,661 individuals based on the Swedish Total Population Register.

    Methods: Eligible individuals were sent postal surveys in 2013 and 2015. The 2 surveys included the same questions about basic demographic data, comorbidities, and chronic pain intensity, spread and sensitivity.

    Results: Several socio-demographic features and comorbidities at baseline were significant predictors of characteristics of pain (intensity, spread and sensitivity) at the 2-year follow-up. When characteristics of pain at baseline were included in the regression analyses they were relatively strong significant predictors of characteristics of pain after 2 years. After this adjustment there were fewer socio-demographic and comorbidity predictors; the effect estimates for those significant predictors had decreased.

    Conclusion: Clinical assessment should focus on several characteristics of pain and include a broad medical screening to capture the overall burden of pain in adults from a longitudinal perspective.

  • 138.
    Larsson, Britt
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Bernfort, Lars
    Linköping University, Department of Medical and Health Sciences, Division of Health Care Analysis. Linköping University, Faculty of Medicine and Health Sciences.
    Levin, Lars-Åke
    Linköping University, Department of Medical and Health Sciences, Division of Health Care Analysis. Linköping University, Faculty of Medicine and Health Sciences.
    Dragioti, Elena
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Distinctive subgroups derived by cluster analysis based on pain and psychological symptoms in Swedish older adults with chronic pain - a population study (PainS65+)2017In: BMC Geriatrics, ISSN 1471-2318, E-ISSN 1471-2318, Vol. 17, article id 200Article in journal (Refereed)
    Abstract [en]

    Background: Improved knowledge based on clinical features of chronic pain in older adults would be valuable in terms of patient-orientated approaches and would provide support for health care systems in optimizing health care resources. This study identifies subgroups based on pain and psychological symptoms among Swedish older adults in the general population and compares derived subgroups with respect to socio-demographics, health aspects, and health care costs. Methods: This cross-sectional study uses data collected from four registers and one survey. The total sample comprised 2415 individuals amp;gt;= 65 years old. A two-step cluster analysis was performed. Data on pain intensity, number of pain sites, anxiety, depression, and pain catastrophizing were used as classification variables. Differences in socio-demographics, quality of life, general health, insomnia, and health care costs among the clusters were investigated. Association of the clusters with the above parameters was further evaluated using multinomial logistic regression. Results: Four major clusters were identified: Subgroup 1 (n = 325; 15%) - moderate pain and high psychological symptoms; Subgroup 2 (n = 516; 22%) - high pain and moderate psychological symptoms; Subgroup 3 (n = 686; 30%) - low pain and moderate psychological symptoms; and Subgroup 4 (n = 767; 33%) - low pain and low psychological symptoms. Significant differences were found between the four clusters with regard to age, sex, educational level, family status, quality of life, general health, insomnia, and health care costs. The multinomial logistic regression analysis revealed that Subgroups 1 and 2, compared to Subgroup 4, were significantly associated with decreased quality of life, decreased general health, and increased insomnia. Subgroup 3, compared to Subgroup 4, was associated with decreased general health and increased insomnia. In addition, compared to Subgroup 4, Subgroups 1 and 2 were significantly associated with higher health care costs. Conclusions: Two high risk clusters of older adults suffering from chronic pain; one mainly based on psychological symptoms and one mainly on pain intensity and pain spread, associated with decreased quality of life and health and increased health care costs were identified. Our findings indicate that subgroup-specific treatment will improve pain management and reduce health care costs.

  • 139.
    Larsson, Britt
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Björk, Jonas
    Lund University, Sweden.
    Grimby-Ekman, Anna
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. University of Gothenburg, Sweden.
    Pain Sensitivity and its Relation to Spreading on the Body, Intensity, Frequency, and Duration of Pain A Cross-Sectional Population-based Study (SwePain)2017In: The Clinical Journal of Pain, ISSN 0749-8047, E-ISSN 1536-5409, Vol. 33, no 7, p. 579-587Article in journal (Refereed)
    Abstract [en]

    Objectives:Individuals with chronic pain often report increased pain sensitivity compared with pain-free individuals; hence, it is crucial to determine whether and how different pain characteristics influence or interact with pain sensitivity. An alternative to experimental pain sensitivity testing is the self-reported pain sensitivity questionnaire (PSQ), which captures pain sensitivity in various body areas.This study compares PSQ in individuals with and without pain and clarifies how pain sensitivity relates to spreading of pain on the body, and to intensity, frequency, duration of pain and to age and sex.Materials and Methods:A total of 5905 individuals with pain and 572 individuals without pain from the general population in southeastern Sweden completed and returned a postal questionnaire.Results:The mean PSQ score was 3.9 (95% confidence interval [CI], 3.88-3.98) in individuals with pain and 3.5 (95% CI, 3.38-3.64) in pain-free individuals. Hence, PSQ was the highest among individuals with pain, with a difference of 0.4 (95% CI, 0.30-0.56). There was a considerable variation in the PSQ values (mean=3.5; SD=1.54) among pain-free individuals. Pain sensitivity was positively related to spreading, intensity, and frequency of pain, with a correlation coefficient of 0.3. PSQ was higher in widespread pain, 4.5 (95% CI, 4.27-4.69) in women and 4.3 (95% CI, 3.94-4.71) in men, than in local pain, 3.7 (95% CI, 3.61-3.91) in women and 3.8 (95% CI, 3.66-3.95) in men. The score for women with regional pain was between local and widespread pain at 4.0 (95% CI, 3.95-4.11) and that for men with regional pain was 3.8 (95% CI, 3.69-3.87), which is equal to that of local pain.Discussion:The positive association between pain sensitivity and spreading of pain on the body provides some evidence that the extent of spreading may be related to the degree of pain sensitivity. Before clinical use of PSQ, psychometric development and further research are needed.

  • 140.
    Larsson, Britt
    et al.
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Rosendal, L
    DanTrials AS, Denmark.
    Kristiansen, J
    Denmark.
    Sjogaard, G
    Denmark.
    Sogaard, K
    Denmark.
    Ghafouri, Bijar
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Abdiu, Avni
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Reconstruction Centre, Department of Plastic Surgery, Hand surgery UHL.
    Kjaer, M
    Bispebjerg Hospital.
    Gerdle, Björn
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Responses of algesic and metabolic substances to 8 h of repetitive manual work in myalgic human trapezius muscle2008In: Pain, ISSN 0304-3959, E-ISSN 1872-6623, Vol. 140, no 3, p. 479-490Article in journal (Refereed)
    Abstract [en]

    The trapezius muscle often develops pain as the result of repetitive and stressful work tasks although it is unclear to what extent this pain is due to alterations in muscle concentrations of algesic/nociceptive substances. Twenty women with chronic neck- and shoulder pain (TM) whose work required highly repetitive work tasks and 20 pain-free female colleagues (CON) were studied during and after a full 8-hour workday. We collected microdialysates from their dominant/most painful trapezius muscle; concentrations of serotonin, glutamate, lactate, pyruvate, potassium, bradykinin, and cytokines and blood flow were determined. In addition, we measured surface electromyogram, task exposure level, pain intensity, perceived mental stress, and urine-cortisol. In connection to the clinical neck and Shoulder examination, we determined pressure pain thresholds (PPTs) over the trapezius and tibialis muscles. TM had higher concentrations Of glutamate (71 +/- 42 vs. 36 +/- 15 mu mol l(-1)) and pyruvate (187 +/- 89 vs. 125 +/- 63 mu mol l(-1)) than CON. Interstitial serotonin was higher ill TM (before work: 10.6 +/- 10.8 vs. 2.2 +/- 1.2 nM; after work: 9.2 +/- 8.3 vs. 1.5 +/- 2.9 nM). The trapezius blood flow during the working day was higher in TM than in CON. TM had lower PPT and higher pain intensity throughout the working day. No differences in EMG, task exposure level, Mental Stress, Or Urine-cortisol in the groups were found. These findings Support the idea that peripheral nociceptive processes are activated ill Occupationally active Subjects, who are diagnosed with trapezius myalgia. In contrast, no sign of low blood flow or increased stress or muscle activity markers were found in TM.

  • 141.
    Lauche, Romy
    et al.
    University of Duisburg-Essen, Germany .
    Cramer, Holger
    University of Duisburg-Essen, Germany .
    Langhorst, Jost
    University of Duisburg-Essen, Germany .
    Dobos, Gustav
    University of Duisburg-Essen, Germany .
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Neck pain intensity does not predict pressure pain hyperalgesia: re-analysis of seven randomized controlled trials2014In: Journal of Rehabilitation Medicine, ISSN 1650-1977, E-ISSN 1651-2081, Vol. 46, no 6, p. 553-560Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES:

    To determine factors, including pain intensity, associated with pressure pain sensitivity in chronic non-specific neck pain and with changes after therapeutic interventions.

    METHODS:

    This re-analysis used pooled data from 7 randomized controlled clinical trials. Pressure pain thresholds were assessed at the hand and at the site of maximal pain in the neck region before and after different non-pharmacological interventions. Age, gender, neck pain intensity and duration, mental health, expectancy and time interval between measurements were used to determine factors influencing pressure pain thresholds as well as pressure pain threshold changes.

    RESULTS:

    A total of 346 patients (77 males, 269 females, mean age 52.6 years (standard deviation 12.0 years)) were included in study, 306 of whom provided a complete data-set for analysis. Pressure pain thresholds at the neck area or the hand did not correlate with pain intensity. Changes in pressure pain thresholds correlated with time between measurements, indicating time-sensitive changes.

    DISCUSSION:

    No coherent correlations between pressure pain thresholds and pain intensity were found. Further research is needed to evaluate the relationship between pain intensity and pressure pain thresholds before its use as a valid substitute of pain rating can be supported. Until then, the results of trials with respect to using pressure pain thresholds as an outcome variable must be interpreted with care.

  • 142.
    Lemming, Dag
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Börsbo, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Sjörs, Anna
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Lind, Eva-Britt
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Arendt-Nielsen, Lars
    Laboratory for Experimental Pain Research and Center for Neuroplasticity and Pain, Center for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
    Graven-Nielsen, Thomas
    Center for Neuroplasticity and Pain, Center for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Cuff Pressure Pain Detection Is Associated with Both Sex and Physical Activity Level in Nonathletic Healthy Subjects2017In: Pain medicine (Malden, Mass.), ISSN 1526-2375, E-ISSN 1526-4637, Vol. 18, no 8, p. 1573-1581Article in journal (Refereed)
    Abstract [en]

    Purpose. The aim of this study was to evaluate pressure pain sensitivity on leg and arm in 98 healthy persons (50 women) using cuff algometry. Furthermore, associations with sex and physical activity level were investigated.

    Method. Normal physical activity level was defined as Godin Leisure-Time Exercise Questionnaire (GLTEQ) score ≤ 45 and high activity level as GLTEQ > 45. A pneumatic double-chamber cuff was placed around the arm or leg where a single chamber was inflated. The cuff inflation rate (1 kPa/s) was constant, and pain intensity was registered continuously on a 10 cm electronic visual analogue scale (VAS). The pain detection threshold (PDT) was defined as when the pressure was perceived as painful, and pain tolerance (PTT) was when the subject terminated the cuff inflation. For PTT, the corresponding VAS score was recorded (VAS-PTT). The protocol was repeated with two chambers inflated.

    Result. Only single cuff results are given. For women compared with men, the PDT was lower when assessed in the arm (P = 0.002), PTTs were lower in the arm and leg (P < 0.001), and the VAS-PTT was higher in the arm and leg (P < 0.033). Highly active participants compared with less active had higher PDT (P = 0.027) in the leg. Women showed facilitated spatial summation (P < 0.014) in the arm and leg and a steeper VAS slope (i.e., the slope of the VAS pressure curve between PDT and PPT) in the arm and leg (P < 0.003).

    Conclusion. This study indicates that reduced pressure pain sensitivity is associated both with male sex and physical activity level.

  • 143.
    Lemming, Dag
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Börsbo, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences.
    Sjörs, Anna
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences.
    Lind, Eva-Britt
    Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Arendt-Nielsen, Lars
    Center for Sensory-Motor Interaction (SMI), Laboratory for Experimental Pain Research, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
    Graven-Nielsen, Thomas
    Center for Sensory-Motor Interaction (SMI), Laboratory for Experimental Pain Research, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Single-point but not tonic cuff pressure pain sensitivity is associated with level of physical fitness: a study of non-athletic healthy subjects2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 5, article id e0125432Article in journal (Refereed)
    Abstract [en]

    Exercise is often used for pain rehabilitation but the link between physical activity level and pain sensitivity is still not fully understood. Pressure pain sensitivity to cuff algometry and conditioned pain modulation (CPM) were evaluated in highly active men (n=22), normally active men (n=26), highly active women (n=27) and normally active women (n=23) based on the Godin Leisure-Time Exercise Questionnaire. Cuff pressure pain sensitivity was assessed at the arm and lower leg. The subjects scored the pain intensity on an electronic Visual Analogue Scale (VAS) during ten minutes with 25 kPa constant cuff pressure and two minutes with zero pressure. The maximal VAS score and area under the VAS-curve were extracted. Pressure pain thresholds (PPT) were recorded by manual pressure algometry on the ipsilateral tibialis anterior muscle before, during and after the tonic arm stimulation.

    Tonic cuff stimulation of the arm and leg resulted in higher VAS peak scores in women compared with men (p<0.04). In all groups the PPTs were reduced during and after the cuff stimulation compared with baseline (p=0.001). PPT were higher in men compared with women (p=0.03) and higher in highly physical active compared with normal active (p=0.048). 

    Besides the well-known gender difference in pressure pain sensitivity this study demonstrates  that a high physical fitness degree in non-athletic subjects is associated with increased pressure pain thresholds but does not affect cuff pressure pain sensitivity in healthy people.

  • 144.
    Lemming, Dag
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences.
    Graven-Nielsen, T.
    Sörensen, Jan
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences.
    Arendt-Nielsen, L.
    Gerdle, Björn
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences.
    Facilitated temporal summation and generalized hyperalgesia in whiplash associated disorder2008Article in journal (Refereed)
  • 145.
    Lemming, Dag
    et al.
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Sinnescentrum, Pain and Rehabilitation Centre.
    Graven-Nielsen, Thomas
    Aalborg University, Denmark .
    Sörensen, Jan
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Sinnescentrum, Pain and Rehabilitation Centre.
    Arendt-Nielsen, Lars
    Aalborg University, Denmark .
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Rehabilitation Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Sinnescentrum, Pain and Rehabilitation Centre.
    Widespread pain hypersensitivity and facilitated temporal summation of deep tissue pain in whiplash associated disorder: an explorative study of women2012In: Journal of Rehabilitation Medicine, ISSN 1650-1977, E-ISSN 1651-2081, Vol. 44, no 8, p. 648-657Article in journal (Refereed)
    Abstract [en]

    Objective: Widespread deep tissue pain hyperalgesia was evaluated in women with chronic whiplash associated disorder (n=25) and controls (n=10) using computerized cuff pressure algometry and hypertonic saline infusion. Methods: A pneumatic double-chamber cuff was placed around: (i) the arm and (ii) the leg. Cuff inflation rate was constant and the pain intensity was registered continuously on a visual analogue scale (VAS); thresholds of detection and tolerance were extracted. For assessment of spatial summation the protocol was repeated with a single-chamber cuff inflated around the leg. Temporal summation of pain was assessed from the leg with constant cuff pressure stimulation at 2 different pressure intensities for 10 min. Hypertonic saline was infused in the tibialis anterior muscle. Results: Cuff pressure pain thresholds were lower in subjects with whiplash associated disorder compared with controls (pless than0.05). Tonic pressure stimulation evoked higher maximal VAS and larger areas under the VAS curve in subjects with whiplash associated disorder compared with controls (pless than0.05). The pain threshold and tolerance were higher during single cuff than double cuff stimulation. The area under the VAS curve after intramuscular saline infusion was larger in whiplash associated disorder (pless than0.05). Conclusion: The results indicated widespread hyperalgesia in chronic whiplash associated disorder and facilitated temporal summation outside the primary pain area, suggesting involvement of central sensitization.

  • 146.
    Lemming, Dag
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences.
    Sörensen, Jan
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences.
    Graven-Nielsen, Thomas
    Center for Sensory-Motor Interaction, Laboratory for Experimental Pain Research, Aalborg University, Denmark.
    Arendt-Nielsen, Lars
    Center for Sensory-Motor Interaction, Laboratory for Experimental Pain Research, Aalborg University, Denmark.
    Gerdle, Björn
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences.
    The responses to pharmacological challenges and experimental pain in patients with chronic whiplash-associated pain2005In: The Clinical Journal of Pain, ISSN 0749-8047, E-ISSN 1536-5409, Vol. 21, no 5, p. 412-421Article in journal (Refereed)
    Abstract [en]

    Objectives: This study evaluates the analgesic responses to intravenous administration of morphine, lidocaine, and ketamine and their relations to duration of chronic pain after whiplash trauma. In addition, experimental muscle pain sensitivity and its correlation to pain duration and pharmacological responses were assessed.

    Methods: Thirty-three patients with diagnosed whiplash-associated disorder grade II in the chronic stage, according to the Quebec classification, were included. The pharmacological evaluation was performed in a randomized, double-blind, cross-over design and consisted of a 30-minute period of intravenous administration of morphine (0.3 mg/kg), lidocaine (5 mg/kg), ketamine (0.3 mg/kg), or placebo (isotonic saline). Intensity ratings of habitual pain on a visual analogue scale were taken before, during, and after the infusion. The patients were classified as nonresponders, placebo-responders, or responders (minimum 50% decrease of pain intensity) of the drugs. Pressure pain thresholds and intramuscular and cutaneous electrical stimulation pain thresholds were measured. The pain intensity during experimental muscle pain by intramuscular hypertonic saline was also recorded. Experimental pain assessments were performed on the lower legs outside the habitual painful area.

    Results: Thirty patients completed the study; 2 were placebo responders and 10 were nonresponders. Of 18 responders, there were 15 morphine responders, 11 lidocaine responders, and 14 ketamine responders. In the patients with whiplash-associated disorder duration less than 2 years, 7 responded to morphine, 5 to lidocaine, and 8 to ketamine. In the patients with pain duration longer than 2 years, 8 responded to morphine, 6 to lidocaine, and 6 to ketamine. Thus, no pattern with respect to pain duration was found. Seventeen patients participated in the experimental pain assessment, and no significant differences in the variables of the intramuscular and cutaneous stimulation and intramuscular-induced pain with respect to response to the pharmacological challenges or whiplash-associated disorder duration existed.

    Discussion: The pharmacological challenges identified subgroups of patients with chronic whiplash-associated disorder that might be considered before instituting therapeutic interventions or research. However, the pattern of responses to the pharmacological challenges did not show any clear relationships with pain duration or the experimental pain tests.

  • 147.
    Lemming, Dag
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Sörensen, Jan
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Graven-Nielsen, Thomas
    Center for Sensory-Motor Interaction (SMI), Laboratory for Experimental Pain Research, Aalborg University, Denmark.
    Lauber, Rolf
    Department of Anesthesiology, University Hospital, Bern, Switzerland.
    Arendt-Nielsen, Lars
    Center for Sensory-Motor Interaction (SMI), Laboratory for Experimental Pain Research, Aalborg University, Denmark.
    Gerdle, Björn
    Linköping University, Department of Clinical and Experimental Medicine, Rehabilitation Medicine . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Pain and Rehabilitation Centre.
    Managing chronic whiplash associated pain with a combination of low-dose opioid (remifentanil) and NMDA-antagonist (ketamine)2007In: European Journal of Pain, ISSN 1090-3801, E-ISSN 1532-2149, Vol. 11, no 7, p. 719-732Article in journal (Refereed)
    Abstract [en]

    The aim was to investigate the efficacy of a combination of low-dose remifentanil (REMI) and ketamine (KET) compared to the single drugs and placebo (P) on whiplash associated pain (WAD) in a double-blind, randomized, placebo-controlled, cross-over study.

    Twenty patients with chronic (>1 year) WAD were included. Four different drug combinations were tested in four sessions: placebo/placebo (P/P), placebo/remifentanil (P/REMI), ketamine/placebo (KET/P) and ketamine/remifentanil (KET/REMI). Target concentrations were 1 and 2 ng/ml (stepwise) for remifentanil and 100 ng/ml for ketamine.

    Habitual pain intensity was assessed on a visual analogue scale (VAS). Experimental pain was assessed with electrical stimulation (single and repeated) of tibialis anterior (TA) muscle, pressure pain algometry applied over infraspinatus (IS) and TA muscles and VAS scores after intramuscular hypertonic saline infusion in TA.

    KET/REMI significantly reduced habitual pain. KET/REMI infused at low REMI target concentration (1 ng/ml) significantly elevated electrical intramuscular pain thresholds (single and repeated). Pain thresholds to electrical stimulation were similarly increased by both P/REMI and KET/REMI at 2 ng/ml target concentration. Pressure pain thresholds were increased by both KET/REMI and P/REMI. VAS-scores after intramuscular saline were also similarly decreased by both REMI combinations. Seven out of 20 subjects were non-responders (<50% pain relief). No correlation was found between effects on spontaneous pain and experimental pain.

    KET/REMI showed an analgesic effect on habitual pain. Experimental pain was attenuated by both combinations containing the opioid, however, KET seemed to enhance the effect of REMI on electrical pain thresholds when a low REMI target concentration was used.

  • 148.
    Lind, Anne-Li
    et al.
    Uppsala Univ, Sweden.
    Just, David
    KTH Royal Inst Technol, Sweden.
    Mikus, Maria
    KTH Royal Inst Technol, Sweden.
    Fredolini, Claudia
    KTH Royal Inst Technol, Sweden.
    Ioannou, Marina
    KTH Royal Inst Technol, Sweden.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Ghafouri, Bijar
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Bäckryd, Emmanuel
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Tanum, Lars
    Akershus Univ Hosp, Norway.
    Gordh, Torsten
    Uppsala Univ, Sweden.
    Manberg, Anna
    KTH Royal Inst Technol, Sweden.
    CSF levels of apolipoprotein C1 and autotaxin found to associate with neuropathic pain and fibromyalgia2019In: Journal of Pain Research, ISSN 1178-7090, E-ISSN 1178-7090, Vol. 12, p. 2875-2889Article in journal (Refereed)
    Abstract [en]

    Objective: Neuropathic pain and fibromyalgia are two common and poorly understood chronic pain conditions that lack satisfactory treatments, cause substantial suffering and societal costs. Today, there are no biological markers on which to base chronic pain diagnoses, treatment choices or to understand the pathophysiology of pain for the individual patient. This study aimed to investigate cerebrospinal fluid (CSF) protein profiles potentially associated with fibromyalgia and neuropathic pain. Methods: CSF samples were collected from 25 patients with neuropathic pain (two independent sets, n=14 patients for discovery, and n=11 for verification), 40 patients with fibromyalgia and 134 controls without neurological disease from two different populations. CSF protein profiling of 55 proteins was performed using antibody suspension bead array technology. Results: We found increased levels of apolipoprotein C1 (APOC1) in CSF of neuropathic pain patients compared to controls and there was a trend for increased levels also in fibromyalgia patients. In addition, levels of ectonucleotide pyrophosphatase family member 2 (ENPP2, also referred to as autotaxin) were increased in the CSF of fibromyalgia patients compared to all other groups including patients with neuropathic pain. Conclusion: The increased levels of APOC1 and ENPP2 found in neuropathic pain and fibromyalgia patients may shed light on the underlying mechanisms of these conditions. Further investigation is required to elucidate their role in maintaining pain and other main symptoms of these disorders.

  • 149.
    Lindbäck, Yvonne
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Physiotherapy. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Local Health Care Services in Central Östergötland, Primary Health Care in Central County.
    Tropp, Hans
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Spinal Surgery.
    Enthoven, Paul
    Linköping University, Department of Medical and Health Sciences, Division of Physiotherapy. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Local Health Care Services in West Östergötland, Research & Development Unit in Local Health Care.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Abbott, Allan
    Linköping University, Department of Medical and Health Sciences, Division of Physiotherapy. Linköping University, Faculty of Medicine and Health Sciences. Bond University, Australia.
    Öberg, Birgitta
    Linköping University, Department of Medical and Health Sciences, Division of Physiotherapy. Linköping University, Faculty of Medicine and Health Sciences.
    Altered somatosensory profile according to quantitative sensory testing in patients with degenerative lumbar spine disorders scheduled for surgery2017In: BMC Musculoskeletal Disorders, ISSN 1471-2474, E-ISSN 1471-2474, Vol. 18, article id 264Article in journal (Refereed)
    Abstract [en]

    Background: Somatosensory profiling in affected and non-affected body regions can strengthen our insight regarding the underlying pain mechanisms, which can be valuable in treatment decision making and to improve outcomes, in patients with degenerative lumbar spine disorders pre-surgery. The aim was to describe somatosensory profiles in patients with degenerative lumbar spine disorders, to identify the proportion with altered somatosensory profile, and to analyze demographic characteristics, self-reported function, pain, and health pre- and 3 months post-surgery. Methods: In this prospective cohort study in a Spine Clinic, 105 patients scheduled for surgery for spinal stenosis, disc herniation, degenerative disc disease, or spondylolisthesis were consecutively recruited. Exclusion criteria were; indication for acute surgery or previous surgery at the same spinal level or severe grade of pathology. Quantitative sensory testing (QST) and self-reported function, pain, and health was measured pre- and 3 months post-surgery. The somatosensory profile included cold detection threshold, warmth detection threshold, cold pain threshold, heat pain threshold and pressure pain threshold in affected and non-affected body regions. Results: On a group level, the patients somatosensory profiles were within the 95% confidence interval (CI) from normative reference data means. On an individual level, an altered somatosensory profile was defined as having two or more body regions (including a non-affected region) with QST values outside of normal ranges for reference data. The 23 patients (22%) with altered somatosensory profiles, with mostly loss of function, were older (P = 0.031), more often female (P = 0.005), had higher back and leg pain (P = 0.016, 0.020), lower mental health component summary score (SF 36 MCS) (P = 0.004) and larger pain distribution (P = 0.047), compared to others in the cohort. Post-surgery there was a tendency to worse pain, function and health in the group with altered somatosensory profile pre-surgery. Conclusions: On a group level, patients with degenerative lumbar spine disorders scheduled for surgery were within normal range for the QST measurements compared to reference values. On an individual level, an altered somatosensory profile outside of normal range in both affected and non-affected body regions occurred in 22% of patients, which may indicate disturbed somatosensory function. Those patients had mostly loss of sensory function and had worse self-reported outcome pre-surgery, compared to the rest of the cohort. Future prospective studies are needed to further examine whether these dimensions can be useful in predicting post-surgery outcome and guide need of additional treatments.

  • 150.
    Lindbäck, Yvonne
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Physiotherapy. Linköping University, Faculty of Medicine and Health Sciences.
    Tropp, Hans
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Spinal Surgery.
    Enthoven, Paul
    Linköping University, Department of Medical and Health Sciences, Division of Physiotherapy. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Local Health Care Services in West Östergötland, Research & Development Unit in Local Health Care.
    Gerdle, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Pain and Rehabilitation Center.
    Abbott, Allan
    Linköping University, Department of Medical and Health Sciences, Division of Physiotherapy. Linköping University, Faculty of Medicine and Health Sciences. Faculty of Health Science and Medicine, Bond University, Gold Coast, Australia.
    Öberg, Birgitta
    Linköping University, Department of Medical and Health Sciences, Division of Physiotherapy. Linköping University, Faculty of Medicine and Health Sciences.
    Association between pain sensitivity in the hand and outcomes after surgery in patients with lumbar disc herniation or spinal stenosis.2017In: European spine journal, ISSN 0940-6719, E-ISSN 1432-0932, Vol. 26, no 10, p. 2581-2588Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To investigate the association between pain sensitivity in the hand pre-surgery, and patient-reported outcomes (PROs) in function, pain and health pre- and post-surgery in patients with disc herniation or spinal stenosis.

    METHODS: This is a prospective cohort study with 82 patients. Associations between pressure-, cold- and heat pain threshold (PPT, CPT, HPT) in the hand pre-surgery and Oswestry, VAS pain, EQ-5D, HADS, and Self-Efficacy Scale, pre- and three months post-surgery; were investigated with linear regression.

    RESULTS: Patients with disc herniation more sensitive to pressure pain pre-surgery showed lower function and self-efficacy, and higher anxiety and depression pre-surgery, and lower function, and self-efficacy, and higher pain post-surgery. Results for cold pain were similar. In patients with spinal stenosis few associations with PROs were found and none for HPT and PROs.

    CONCLUSIONS: Altered pain response in pressure- and cold pain in the hand, as a sign of widespread pain pre-surgery had associations with higher pain, lower function and self-efficacy post-surgery in patients with disc herniation.

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