No Alterations in ACL Injury Risk Factors in Preadolescent Elite Female Handball Players Following an Eight-Week Targeted Training Intervention: A Randomised Controlled Trial

Adolescent female handball players are at elevated risk of anterior cruciate ligament (ACL) injury. Early interventions during preadolescence seem crucial for improving motor strategies and potentially preventing injuries. This randomised controlled trial on preadolescent female handball players investigated the effects of an 8-week ACL injury prevention program (ACL-IPP) targeting modifiable neuromuscular and biomechanical risk factors and assessed retention effects 8 weeks post-intervention. Thirty-five elite preadolescent female handball players (11-13 years old) were randomised to the ACL-IPP group ( n  = 18) or a control group that performed shoulder injury prevention exercises ( n  = 17), with supervised training conducted for 15 min twice weekly. Biomechanical and neuromuscular assessments of participants' side-cutting manoeuvres were performed at baseline, immediately after the 8-week intervention (post-intervention) and at an 8-week follow-up (16 weeks from baseline). The primary outcome was the between-group change in m. semitendinosus EMG preactivity, measured during the 50 ms preceding initial contact of the side-cutting manoeuvre at 8 weeks. There were no significant between-group differences in changes in semitendinosus preactivity ( p = 0.950), isometric hip external rotation strength, hip flexion, knee internal rotation at initial contact or peak knee abduction moments of the handball-specific side-cut manoeuvre. Similarly, no retention effects were observed after 16 weeks. These findings suggest that the implemented 8-week ACL-IPP was insufficient to elicit meaningful improvements in ACL injury risk factors in this population. Greater training volume, different exercise selection and/or extended intervention duration may be required to induce neuromuscular and biomechanical adaptations in preadolescent female handball players. Trial Registration: ClinicalTrials.gov identifier: NCT05955599.