The Effects of an Injury Prevention Program on Landing Biomechanics Over Time

Abstract

Background: Knowledge is limited regarding how long improvements in biomechanics remain after completion of a lower extremity injury prevention program. Purpose: To evaluate the effects of an injury prevention program on movement technique and peak vertical ground-reaction forces (VGRF) over time compared with a standard warm-up (SWU) program. Study Design: Controlled laboratory study. Methods: A total of 1104 incoming freshmen (age range, 17-22 years) at a military academy in the United States volunteered to participate. Participants were cluster-randomized by military company to either the Dynamic Integrated Movement Enhancement (DIME) injury prevention program or SWU. A random subsample of participants completed a standardized jump-landing task at each time point: immediately before the intervention (PRE), immediately after (POST), and 2 (POST2M), 4 (POST4M), 6 (POST6M), and 8 months (POST8M) after the intervention. VGRF data collected during the jump-landing task were normalized to body weight (%BW). The Landing Error Scoring System (LESS) was used to evaluate movement technique during the jump landing. The change scores (Δ) for each variable (LESS, VGRF) between the group’s average value at PRE and each time point were calculated. Separate univariate analyses of variance were performed to evaluate group differences. Results: The results showed a greater decrease in mean (±SD) VGRF in the DIME group compared with the SWU group at all retention time points: POST2M (SWU [Δ%BW], −0.13 ± 0.82; DIME, −0.62 ± 0.91; P = .001), POST4M (SWU, −0.15 ± 0.98; DIME,−0.46 ± 0.64; P = .04), POST6M (SWU, −0.04 ± 0.96; DIME, −0.53 ± 0.83; P = .004), and POST8M (SWU, 0.38 ± 0.95; DIME, −0.11 ± 0.98; P = .003), but there was not a significant improvement in the DIME group between PRE and POST8M (Δ%BW, −0.11 ± 0.98). No group differences in Δ LESS were observed. Conclusion: The study findings demonstrated that an injury prevention program performed as a warm-up can reduce vertical ground-reaction forces compared with a standard warm-up but a maintenance program is likely necessary in order for continued benefit. Clinical Relevance: Injury prevention programs may need to be performed constantly, or at least every sport season, in order for participants to maintain the protective effects against injury.