The Effects of Exercise for the Prevention of Overuse Anterior Knee Pain A Randomized Controlled Trial

Background: Anterior knee pain (AKP) is the most common activity-related injury of the knee. The authors investigated the effect of an exercise intervention on the incidence of AKP in UK army recruits undergoing a 14-week physically arduous training program. Hypothesis: Modifying military training to include targeted preventative exercises may reduce the incidence of AKP in a young recruit population. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A single-blind cluster randomized controlled trial was performed in 39 male and 11 female training groups (median age: 19.7 years; interquartile range, 17-25) undergoing phase 1 of army recruit training. Each group was randomly assigned to either an intervention (n = 759) or control (n = 743) protocol. The intervention consisted of 4 strengthening and 4 stretching exercises completed during supervised physical training lessons (7 per week). The control group followed the existing training syllabus warm-up exercises. The primary outcome was a diagnosis of AKP during the 14-week training program. Results: Forty-six participants (3.1%; 95% confidence interval [CI], 2.3-4.1) were diagnosed with AKP. There were 36 (4.8%; 95% CI, 3.5-6.7) new cases of AKP in the control group and 10 (1.3%; 0.7-2.4) in the intervention group. There was a 75% reduction in AKP risk in the intervention group (unadjusted hazard ratio = 0.25; 95% CI, 0.13-0.52; P<.001). Three participants (0.4%) from the intervention group were discharged from the military for medical reasons compared to 25 (3.4%) in the control group. Conclusion: A simple set of lower limb stretching and strengthening exercises resulted in a substantial and safe reduction in the incidence of AKP in a young military population undertaking a physical conditioning program. Such exercises could also be beneficial for preventing this common injury among nonmilitary participants in recreational physical activity.