35 Health and performance promotion in youth sport (HAPPY): two matches within 72 hours increases knee injury risk in youth handball

Introduction This study investigated whether playing two or more matches less than 72 hours apart was associated with an increase in young handball players’ knee injury rates the following week compared with playing one or no matches.Materials and Methods 731 Danish handball players aged 11–17 years (47% boys) reported weekly on handball exposure (match and training hours) and any new handball related knee injury over 30 weeks using the Oslo Sports Trauma Research Center Health 2 questionnaire. Match congestion was categorized as: (Low) ≤1 match (reference group) or (High) ≥2 matches played within 72 hours, based on data from the Danish Handball database. Cox proportion hazard models were used to estimate (HRs) and 95% confidence intervals (95% CI) using calendar week as time scale and adjusting for weekly handball exposure, team gender, and previous knee injury.Results 157 new knee injuries were reported in the weeks following 20.285 matches. Of these matches, 2.193 matches were played within a 72-hour interval. In the high congestion group, 24 new knee injuries occurred. High match congestion was associated with a 71% higher knee injury rate (HR=1.71 [95% CI; 1.23–2.40]) compared with those in the low congestion group with a longer recovery period between matches.Conclusion Playing two or more matches within a 72-hour period increases the new knee injury rate the following week in young handball players. This suggests handball matches to be scheduled at least 72 hours apart to reduce knee injury risk in young players.