Injuries in male professional football: A prospective comparison between individual and team-based exposure registration.

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 categorization 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 IBE recording, and inter-agreement in injury categorization was very high.

Gradual increase in the risk of match injury in Norwegian male professional football: a 6-year prospective study.

The aim of this study was to monitor injury incidence and pattern in Norwegian male professional football over six consecutive seasons and compare the risk of injury between the preseason and competitive season. All time loss injuries were recorded by the medical staff of each club. In total, 2365 injuries were recorded. The incidence of acute injuries was 15.9/1000 match hours [95% confidence interval (CI): 14.9-16.8], 1.9/1000 training hours (95% CI: 1.7-2.0), and 1.4 (95% CI: 1.3-1.5) overuse injuries/1000 h. A linear regression model found an annual increase of 1.06 acute match injuries/1000 h (95% CI: 0.40-1.73), corresponding to a total increase of 49% during the 6-year study period. When accounting for interteam variation and clustering effects using a general estimating equation model, the increase in injury incidence was 0.92 (95% CI: -0.11-1.95, P = 0.083). No difference in the risk of acute match injuries (rate ratio (RR): 0.86, 95% CI: 0.73-1.01), acute training injuries (RR: 1.16, 95% CI: 0.99-1.36), or overuse injuries (RR: 1.04, 95% CI: 0.89-1.21) was observed between the preseason and competitive season. In conclusion, the overall risk of acute match injuries in Norwegian male professional football increased by 49% during the study period, although this increase was not fully consistent across teams. We detected no change in the risk of training and overuse injuries or any difference between the preseason and competitive season.

Injury surveillance in male professional football; is medical staff reporting complete and accurate?

Since the 2000 season, an injury surveillance system has been established to monitor injury risk and injury patterns in the Norwegian professional football league. The aim of this study was to assess the accuracy of routine injury registration performed by medical staff in professional football. The team medical staff completed injury registration forms on a monthly basis throughout the 2007 season (January-October). Players were interviewed at the end of the season (October/November) about all injuries that occurred from July through September. Thirteen of fourteen teams, 296 of 310 A-squad players were interviewed. An injury was recorded when a player was unable to take fully part in football training or match the day after injury. A total of 174 injuries were registered, 123 acute injuries and 51 overuse injuries. Of these, 141 were reported by medical staff and 122 by players. Eighty-nine injuries (51%) were registered using both methods, 52 (30%) by medical staff only and 33 (19%) by player interviews only. Prospective injury surveillance by team medical staff in Norwegian male professional football underestimates the incidence of time-loss injuries by at least one-fifth.