BackgroundVentilation as a function of elimination of CO2 during incremental exercise (VE/VCO2 slope) has been shown to be a valuable predictor of complications and death after major non-cardiac surgery. VE/VCO2 slope and partial pressure of end-tidal carbon dioxide (PetCO2) are both affected by ventilation/perfusion mismatch, but research on the utility of PetCO2 for risk stratification in major abdominal surgery is limited. AimWe aimed to determine the correlation between VE/VCO2 slope and PetCO2 measured during preoperative cardiopulmonary exercise testing (CPET) and its association with major cardiopulmonary complications (MCPCs) or death following oesophageal and other major abdominal cancer surgeries. MethodIn a retrospective cohort of 116 patients undergoing preoperative CPET 2008-2023, VE/VCO2 slope and PetCO2 (kPa) were recorded. The main outcome was MCPC during hospitalisation or death <= 90 days of surgery. We determined threshold values for each measure, corresponding to 90% specificity, using receiver operating characteristics analysis. ResultsA strong negative correlation was found between PetCO2 after a 5-minute warm-up and VE/VCO2 slope (Pearson r = -.88). In oesophagus cancer, VE/VCO2 slope >38 and PetCO2 < 4.1 kPa (30.8 mmHg) were both significant thresholds for the main outcome. For other major abdominal surgery patients, threshold analyses were non-significant. The area under the curve to predict outcome was similar using VE/VCO2 slope (0.70, 95% confidence interval 0.51-0.89) as compared to PetCO2 (0.71, 0.53-0-90). ConclusionBoth preoperative VE/VCO2 slope and PetCO2 could identify subjects with a very high risk of complications following oesophageal resection, with similar prognostic utility. PetCO2 can be measured with simpler equipment and could therefore be useful when CPET is not available.

Objective: We aimed to evaluate whether or not using the slope of the increase in minute ventilation in relation to carbon dioxide (VE/VCO2-slope), with a cutoff value of 35, could improve risk stratification for major pulmonary complications or death following lobectomy in lung cancer patients at moderate risk (VO2peak = 10-20 mL/kg/min). Methods: Single center, retrospective analysis of 146 patients with lung cancer who underwent lobectomy and preoperative cardiopulmonary exercise testing in 2008-2020. The main outcome was any major pulmonary complication or death within 30 days of surgery. Patients were categorized based on their preoperative cardiopulmonary exercise testing as: low-risk group, peak oxygen uptake >20 mL/kg/min; low-moderate risk, peak oxygen uptake 10 to 20 mL/kg/min and VE/VCO2-slope <35; and moderate-high risk, peak oxygen uptake 10 to 20 mL/kg/min and VE/VCO2-slope =35. The frequency of complications between groups was compared using ?2 test. Logistic regression was used to calculate the odds ratio with 95% CI for the main outcome based on the cardiopulmonary exercise testing group. Results: Overall, 25 patients (17%) experienced a major pulmonary complication or died (2 deaths). The frequency of complications differed between the cardiopulmonary exercise testing groups: 29%, 13%, and 8% in the moderate-high, low-moderate, and low-risk group, respectively (P = .023). Using the low-risk group as reference, the adjusted odds ratio for the low-moderate risk group was 3.44 (95% CI, 0.66-17.90), whereas the odds ratio for the moderate-high risk group was 8.87 (95% CI, 1.86-42.39). Conclusions: Using the VE/VCO2-slope with a cutoff value of 35 improved risk stratification for major pulmonary complications following lobectomy in lung cancer patients with moderate risk based on a peak oxygen uptake of 10 to 20 mL/kg/min. This suggests that the VE/VCO2-slope can be used for preoperative risk evaluation in lung cancer lobectomy. © 2022 The Author(s)

Despite the popularity of the sport, few studies have investigated community-level football injury patterns. This study examines football injuries treated at emergency medical facilities using data from three Swedish counties. An open-cohort design was used based on residents aged 0-59 years in three Swedish counties (pop. 645 520). Data were collected from emergency medical facilities in the study counties between 1 January 2007 and 31 December 2010. Injury frequencies and proportions for age groups stratified by sex were calculated with 95% confidence intervals (95% CIs) and displayed per diagnostic group and body location. Each year, more than 1/200 person aged 0-59 years sustained at least one injury during football play that required emergency medical care. The highest injury incidence was observed among adolescent boys [2009 injuries per 100 000 population years (95% CI 1914-2108)] and adolescent girls [1413 injuries per 100 000 population years (95% CI 1333-1498)]. For female adolescents and adults, knee joint/ligament injury was the outstanding injury type (20% in ages 13-17 years and 34% in ages 18-29 years). For children aged 7-12 years, more than half of the treated injuries involved the upper extremity; fractures constituted about one-third of these injuries. One of every 200 residents aged 0-59 years in typical Swedish counties each year sustained a traumatic football injury that required treatment in emergency healthcare. Further research on community-level patterns of overuse syndromes sustained by participation in football play is warranted.

Methodological considerations of football injury epidemiology have only scarcely been described. The aim of this study was to evaluate the inter-rater agreement in injury capture rate and injury categorisation for data registered in two different prospective injury surveillance audits studying the same two Norwegian male professional football clubs for two consecutive seasons, 2008-2009. One audit used team-based exposure (TBE) recording and the other individual-based exposure (IBE). The number of injuries recorded and corresponding injury rates (injuries/1000 h exposure) were compared between audits. Cohen’s Kappa and Prevalence Adjusted Bias Adjusted Kappa (PABAK) coefficients were calculated for injury variables. Of 323 injuries included, the IBE audit captured 318 (overall capture rate 98.5%, training 98.9%, match 97.8%) and the TBE audit 303 injuries (overall capture rate 93.8%, training 91.4%, match 97.1%). Agreement analysis showed Kappa and PABAK coefficients regarded as almost perfect (> 0.81) for 8 of 9 injury variables, and substantial (ƙ 0.75) for the variable injury severity. In conclusion, the capture rate for training injuries was slightly higher with individual-based exposure recording, and inter-agreement in injury categorisation was very high.

Objectives: To investigate frequent surface shifts, match play on an unaccustomed surface, and climate type as potential risk factors for injury in Scandinavian male professional football.

Design: Prospective cohort study.

Methods: 32 clubs from two climate zones, warm temperate (n=19) and snow climates (n=13), were followed during seasons 2010 and 2011. The association between number of surface shifts during fivematch sequences and subsequent overuse injury risk was evaluated with generalized estimating equations. Injury rate was expressed as time loss injuries/1000 hours, and compared between groups with a rate ratio and 95% confidence interval (CI).

Results: No association was found between the number of surface shifts and subsequent overuse injury risk (risk ratio 1.01, 95% CI 0.91-1.12). Grass clubs (grass installed at home venue) had a lower match injury rate when playing away matches on artificial turf vs. away matches on grass (rate ratio 0.66, 95% CI 0.40-0.89). Analyses on the total cohort showed no difference in injury rates between clubs in the two climate zones, but sub-analyses revealed that grass clubs from the snow climate zone had lower training and match injury rates than grass clubs from the warm temperate zone (rate ratio 0.69, 95% CI 0.55-0.87).

Conclusions: No influence on injury risk was seen from frequent surface shifts or from playing matches on an unaccustomed surface. Climate type at club home venue had minimal influence on injury rates.

Background There are limited data on the nature, type and incidence of illness in football. Previous studies indicate that gastrointestinal and respiratory tract illnesses are most common. Aim To describe the incidence and burden of illness in male professional football. Methods Over the 4-year study period, 2011-2014, 73 professional football teams in Europe participated, with a total of 1 261 367 player-days recorded. All time-loss illnesses were recorded by the medical staff of each club. A recordable illness episode was any physical or psychological symptom (not related to injury) that resulted in the player being unable to participate fully in training or match play. Results A total of 1914 illness episodes were recorded. The illness incidence was 1.5 per 1000 player-days, meaning that, on average, a player experienced an illness episode every second season, with a median of 3 days absence per illness episode. Severe illness (absence amp;gt;4 weeks) constituted 2% of all illnesses. Respiratory tract illness was the most common (58%), followed by gastrointestinal illness (38%). Respiratory tract illness, gastrointestinal illness and cardiovascular illness caused the highest illness burden. Conclusions The illness incidence among male professional football players is low compared with the injury incidence. We found that the highest illness burden was caused by illness to the respiratory tract, gastrointestinal tract and cardiovascular system.

This thesis includes four papers based on three different prospective cohort studies on injury characteristics in men’s professional football. The same general methodology was used in all papers. Time-loss injuries and player individual exposure was registered for match and training separately. The general aim was to investigate potential internal and external risk factors for injury, with a focus on age, playing position, time in professional football, playing surface (artificial turf and natural grass), changes between surfaces and climate; and to evaluate the study methodology.

Paper I was based on data collected between 2001 and 2010 from 26 top professional clubs in Europe; the UCL injury study. In total, 6140 injuries and 797 389 hours of exposure were registered. A decreased general injury rate was observed for newcomers compared with established players (hazard ratio (HR), 0.77; 95% CI 0.61-0.99). Using goalkeepers as a reference, all outfield playing positions had significantly higher age-adjusted injury rates. Using players aged ≤ 21 years as a reference, the overall adjusted injury rate increased with age, with a peak injury rate among players aged 29 to 30  years (HR, 1.44; 95% CI, 1.24-1.68).

Paper II and Paper III are based on data collected during two consecutive seasons, 2010 and 2011, in the Swedish and Norwegian male first leagues. In total, 2186 injuries and 367 490 hours of football exposure were recorded. No statistically significant differences were found in acute injury rates on artificial turf (AT) compared with natural grass (NG) during match play (rate ratio, 0.98, 99% CI 0.79-1.22) or training (rate ratio 1.14, 99% CI 0.86-1.50) when analysing at the individual player level. However, when analysing at the club level, clubs with AT installed at their home arena had a significantly higher acute training injury rate (rate ratio 1.31, 99% CI 1.04-1.63) and overuse injury rate (rate ratio 1.38, 99% CI 1.14-1.65) compared to clubs with NG installed at their home venue. No association was found between frequent surface shifts and subsequent overuse injury risk (risk ratio 1.01, 95% CI 0.91-1.12). Analyses on the total cohort showed no difference in injury rates between clubs in the two climate zones (total rate ratio 1.01, 95% CI 0.92-1.10).

Data included in Paper IV were collected during two consecutive seasons 2008 and 2009. During this period, two Norwegian elite football clubs were concurrently included in two research groups’ surveillance systems. The capture rate for match injuries was similar between the two audits, while the capture rate for training injuries was slightly higher with individual-based exposure recording. The inter-rater agreement in injury variable categorisations was in most aspects very high.

Background less thanbrgreater than less thanbrgreater thanLimited information is available on the variation in injury rates over multiple seasons of professional football. less thanbrgreater than less thanbrgreater thanAim less thanbrgreater than less thanbrgreater thanTo analyse time-trends in injury characteristics of male professional football players over 11 consecutive seasons. less thanbrgreater than less thanbrgreater thanMethods less thanbrgreater than less thanbrgreater thanA total of 1743 players comprising 27 teams from 10 countries were followed prospectively between 2001 and 2012. Team medical staff recorded individual player exposure and time loss injuries. less thanbrgreater than less thanbrgreater thanResults less thanbrgreater than less thanbrgreater thanA total of 8029 time loss injuries were recorded. The match unavailability due to injury was 14% and constant over the study period. On average, a player sustained two injuries per season, resulting in approximately 50 injuries per team and season. The ligament injury rate decreased during the study period (R-2=0.608, b=-0.040, 95% CI -0.065 to -0.016, p=0.005), whereas the rate of muscle injury (R-2=0.228, b=-0.013, 95% CI -0.032 to 0.005, p=0.138) and severe injury (R-2=0.141, b=0.015, 95% CI -0.013 to 0.043, p=0.255) did not change over the study period. In addition, no changes in injury rates over the 11-year period were found for either training (R-2=0.000, b=0.000, 95% CI -0.035 to 0.034, p=0.988) or match play (R-2=0.282, b=-0.015, 95% CI -0.032 to 0.003, p=0.093). less thanbrgreater than less thanbrgreater thanConclusions less thanbrgreater than less thanbrgreater thanThe injury rate has decreased for ligament injuries over the last 11years, but overall training, match injury rates and the rates of muscle injury and severe injury remain high.

Background The influence of injuries on team performance in football has only been scarcely investigated.

Aim To study the association between injury rates and team performance in the domestic league play, and in European cups, in male professional football.

Methods 24 football teams from nine European countries were followed prospectively for 11 seasons (2001–2012), including 155 team-seasons. Individual training and match exposure and time-loss injuries were registered. To analyse the effect of injury rates on performance, a Generalised Estimating Equation was used to fit a linear regression on team-level data. Each team's season injury rate and performance were evaluated using its own preceding season data for comparison in the analyses.

Results 7792 injuries were reported during 1 026 104 exposure hours. The total injury incidence was 7.7 injuries/1000 h, injury burden 130 injury days lost/1000 h and player match availability 86%. Lower injury burden (p=0.011) and higher match availability (p=0.031) were associated with higher final league ranking. Similarly, lower injury incidence (p=0.035), lower injury burden (p<0.001) and higher match availability (p<0.001) were associated with increased points per league match. Finally, lower injury burden (p=0.043) and higher match availability (p=0.048) were associated with an increase in the Union of European Football Association (UEFA) Season Club Coefficient, reflecting success in the UEFA Champions League or Europa League.

Conclusions Injuries had a significant influence on performance in the league play and in European cups in male professional football. The findings stress the importance of injury prevention to increase a team's chances of success.

Background: No study has investigated whether newcomers to professional soccer have a different injury rate than established players.                     

Purpose: The primary objective was to investigate whether being a newcomer to professional soccer influences injury rates. The secondary objective was to evaluate whether playing position and player age influence injury rates.                     

Study Design: Cohort study; Level of evidence, 2.                     

Methods: Twenty-six soccer clubs, with 1401 players, were followed prospectively over 9 consecutive seasons between 2001 and 2010. Club medical staff recorded time-loss injuries and soccer exposure on an individual level. Cox regression analyses were used to evaluate associations between time-loss injuries and time in professional soccer, playing position, and age.                     

Results: In total, 6140 injuries and 797,389 hours of exposure were registered. A decreased general injury rate was observed for newcomers (n = 116) compared with established players (n = 3091) (hazard ratio [HR], 0.77; 95% confidence interval [CI], 0.61-0.99). In contrast, newcomers had a higher rate of fractures (rate ratio [RR], 1.77; 95% CI, 1.05-2.97), especially stress-related bone injuries (RR, 2.68; 95% CI, 1.08-6.69). Using goalkeepers as a reference, all outfield playing positions had significantly higher adjusted injury rates: defenders with an HR of 1.91 (95% CI, 1.64-2.24), midfielders with an HR of 1.78 (95% CI, 1.53-2.07), and forwards with an HR of 1.82 (95% CI, 1.55-2.14). Using players aged ≤21 years as a reference, the overall adjusted injury rate increased with age, with a peak injury rate among players aged 29 to 30 years (HR, 1.44; 95% CI, 1.24-1.68).                     

Conclusion: Newcomers to professional soccer had a lower general injury rate than established players but a higher rate of stress-related bone injuries. Being a goalkeeper was associated with lower injury rates than all outfield playing positions. Injury rates increased with age, a pattern that persisted after adjusting for playing position and match exposure.