Assessing Injury Susceptibility At Marine Corps Recruit Depot, San Diego, California

Abstract

Individuals enlisting at the Marine Corps Recruit Depot (MCRD) San Diego undergo a physically demanding training regimen. As such, musculoskeletal injury (MSKI) rates during training remain high and account for costly increases in attrition and delays in graduation, thereby impacting force readiness. Earlier injury detection is needed, and functional movement tests such as the functional movement screen (FMS), Y-balance test lower quarter (YBT-LQ) and ankle dorsiflexion range of motion (AD-ROM) can provide predictive value for MSKI incidence. PURPOSE: To test the hypothesis that functional movement assessments are beneficial tools for movement analysis and injury prediction. METHODS: Male MCRD recruits (N = 407; mean ± SD: age, 20 ± 2 y; height, 174.5 ± 7.3 cm; weight, 76.1 ± 11.4 kg) underwent testing of FMS, YBT-LQ, and AD-ROM prior to beginning training. Injury incidence during training and graduation outcomes were tracked by instructors. RESULTS: Twelve recruits (3%) were dropped from their class due to a lower body stress fracture or strain, delaying graduation for eight, and separating four from enlistment. A one-way analysis of variance revealed statistical group differences (MSKI vs no MSKI) for the FMS hurdle step (HS; F(1,400) = 4.314, p = 0.038) and trunk stability (TS; F(1,394) = 14.600, p = 0.000) assessments, with lower scores in the MSKI group (HS: 1.9 ± 0.5 vs 2.2 ± 0.5, TS: 1.3 ± 1.2 vs 2.4 ± 0.9). During the YBT-LQ anterior direction, the MSKI group showed a greater difference (F(1,394) = 6.536, p = 0.011) between legs (5.5 ± 4.7 cm vs 3.3 ± 2.8 cm). For both leg-ankle-foot complexes, the MSKI group demonstrated higher AD-ROM scores (right: 44.1 ± 4.7° vs 40.5 ± 6.5°; left: 43.3 ± 5.4° vs 41.6 ± 6.5°) with the right side trending toward significance (F(1, 399) = 3.692, p = 0.055). CONCLUSIONS: MCRD recruits who incurred a lower body MSKI during training had a movement analysis of inferior lower body mobility and stability, weaker core stabilization, and poorer single limb stance and imbalance. The increase in ankle flexibility observed in the MSKI group may be a risk factor for overuse Achilles tendon injuries. Results not only apply to MCRD recruits, but could also apply to recruits in other military branches, athletic communities, and first responders seeking screening tools for movement analysis and injury prediction.