Prevention of overuse injuries by a concurrent exercise program in subjects exposed to an increase in training load -: A randomized controlled trial of 1020 army recruits

Background: It is unknown whether an exercise program can prevent overuse injuries in the lower extremity. An often encountered and important risk factor for the development of lower extremity overuse injuries is an abrupt increase in activity level. Hypothesis: A preventive training program based on a literature review of intrinsic risk factors, and performed concurrent with an increase in physical activity, can reduce the incidence of overuse knee injuries and medial tibial stress syndrome, as well as increase running distance. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 1020 soldiers aged 20.9 years ( range, 19-26 years) undergoing 3 months of basic military training consecutively enrolled from December 2004 to December 2005. The prevention program consisted of an exercise program of 15 minutes' duration 3 times a week, including 5 exercises for strength, flexibility, and coordination; the placebo program consisted of 5 exercises for the upper body. Results: During the observation period, 223 subjects sustained an injury, with 50 and 48 of these fulfilling the study criteria for overuse knee injuries or medial tibial stress syndrome, respectively. There were no significant differences in incidence of injury between the prevention group and the placebo group ( incidence, 0.22 vs 0.19; P = .162; relative risk = 1.05 [ range, 0.98-1.11]). The soldiers in the prevention group had the greater improvement in running distance in 12-minute run tests ( 82 vs 43 m; P = .037). Conclusion: An exercise program with an emphasis on muscular strengthening, coordination, and flexibility based on intrinsic risk factors identified through a literature review did not influence the risk of developing overuse knee injuries or medial tibial stress syndrome in subjects undergoing an increase in physical activity. The program increased maximal running distance in a 12-minute test.