Background: Musculoskeletal injuries (MSKIs) are a significant health concern for active-duty military personnel. This study aimed to investigate the association between body mass index (BMI) and MSKIs among United States active-duty army soldiers (ADAS) and the impact of the COVID-19 pandemic on this association.

Methods: This retrospective cohort study analyzed ADAS data from the Military Health System repository between October 2018 and September 2022. We divided the study period into pre-pandemic, early-pandemic, and late-pandemic phases. We evaluated the solider demographics and used univariate and multivariable analyses to assess the relationship between BMI and MSKI risk.

Results: After exclusions, the final cohort included 204,523 ADAS (85.5% male, 67% White and 33.6% Junior Enlisted). From the pre-pandemic period to the late-pandemic period, the proportion of soldiers in the obese category significantly increased from 18.1% to 27.9%, whereas the soldiers in the healthy-weight category decreased from 31.2% to 23.5%, respectively (p<0.001). Across all categories of BMI, the MSKI prevalence significantly increased from the pre-pandemic period to the late-pandemic period (p<0.001). Furthermore, compared to healthy weight individuals, the risk of MSKI was significantly greater for obese individuals (pre-pandemic period: Odds ratio (OR) 1.13, 95% confidence interval (CI)1.09-1.17, p<0.001; late-pandemic period: OR 1.43, 95% CI 1.39-1.47, p<0.001), after adjusting for age-group, race, sex and rank.

Conclusions: The pandemic's impact on weight gain underscores the critical need for weight management programs and personalized fitness plans. A healthier army translates to a stronger national defense by reducing healthcare burdens and ensuring the operational readiness of warfighters.