Heavy loads and lifting are risk factors for musculoskeletal injuries in deployed female soldiers

Abstract

The purpose of this prospective cohort study was to investigate physical, occupational, and psychosocial risk factors for musculoskeletal injuries (MSI) in deployed female soldiers. Before deployment, participants completed performance testing and surveys and after deployment an additional survey detailing occupational demands and MSI. Data analyzed found 57/160 (36%) suffered 78 MSI. In unadjusted analyses, these factors increased the relative risk (RR, 95% confidence interval) of injury: wearing an average load >10% body weight (BW) (RR = 2.00, 1.31-4.57), wearing an average load >1 hour (RR = 2.44, 1.30-4.57), heaviest load worn >15% BW (RR = 5.83, 1.51-22.50), wearing a backpack (RR = 1.82, 1.23-2.80), wearing body armor >1 hour (RR = 1.62, 1.002-2.62), lifting objects weighing above 22.68 kg (RR = 1.96, 1.08-3.57), lifting objects one to two times (RR = 1.73, 1.002-2.97), carrying objects >7.62 m (RR = 2.01, 1.19-3.42), and Y Balance composite score <95.23 (RR = 1.71, 1.13-2.60). The best logistic regression model predicting MSI was average load as % BW (odds ratio [OR] = 1.04, 1.01-1.07), heaviest load as % BW (OR = 1.03, 1.01-1.05), average repetitions lifting objects (OR = 1.07, 1.01-1.14), and sit-ups (OR = 0.93, 0.93-0.99). Results indicate that risk of MSI in deployed female soldiers increased with heavier equipment worn and more repetitious lifting, although more performing more sit-ups on the fitness test before deployment reduced the risk.