Do niggles matter? : increased injury risk following physical complaints in football (soccer)

Objective: To determine the prevalence and impact of non-time loss injuries in semi-professional football. Methods: 218 players completed the Oslo Sports Trauma Research Centre (OSTRC) Questionnaire on Health Problems weekly during the 2016 season (35 weeks), recording the prevalence and impact of time loss (TL) and non-time loss (non-TL) injuries. TL injury and exposure were also collected by a third party as per the Football Consensus statement. The relative risk (RR) of a TL injury within 7 days of a self-reported non-TL injury was determined, with associated predictive power calculated. Results: The risk of TL injury was 3.6 to 6.9 × higher when preceded by ‘minor’ and ‘moderate’ non-TL complaints, respectively, and good predictive power (22.0–41.8%) was observed (AUC range = 0.73 to 0.83). Compliant responders (80% of completed OSTRC questionnaires) showed a mean self-reported weekly injury prevalence (TL and non-TL combined) of 33% (95% CI–31.4% to 34.6%) with 28% (CI–26.4% to 29.6%) attributed to non-TL injury. Conclusion: Over a quarter of players on average, report a physical complaint each week that does not prevent them from participating in training or match play. A non-TL injury was shown to be useful in identifying individual players at an increased risk of a TL injury.