Health And Performance Promotion in Youth (HAPPY) hybrid effectiveness-implementation cluster randomised trial: comparison of two strategies to implement an injury prevention exercise programme in Danish youth handball

Objective To investigate if a combination of an online and onsite implementation strategy was superior to an online-only strategy in enhancing the use of an injury prevention exercise programme (IPEP) and in reducing the risk of shoulder, knee and ankle injuries in youth community handball players (age 11-17) over a handball season.Methods In this 30-week hybrid effectiveness-implementation cluster randomised type 3 study, 20 youth handball clubs were randomly assigned 1:1 to either a combined online and onsite implementation strategy (coach workshop using the health action process approach behaviour change model and health service provider (HSP) support) or an online-only strategy (control group). The primary implementation outcome was coach-reported adherence, measured as the average IPEP exercise usage by the team over 30 weeks. The primary effectiveness outcome was player-reported handball playing time to any new handball-related shoulder, knee and ankle injuries, reported weekly using the Oslo Sports Trauma Research Centre Questionnaire on Health Problems.Results We enrolled 63 coaches (27% women) and 945 players (mean age 14.5 years, 55% girls). Intention-to-treat analyses showed no statistically significant difference between implementation strategies in adherence (between-group difference 1.4, 95% CI -0.5 to 3.4) or in cumulative injury risk (between-group difference 5.5% points, 95% CI -2.2 to 13.1).Conclusion Our findings demonstrate that in youth community handball, a combined online and onsite implementation strategy, including a coach workshop and HSP support, was not superior to an online-only strategy regarding adherence to an IPEP or in reducing shoulder, knee and ankle injury risk.Trial registration number NCT05294237.