Three-thousand Meters Run Time Predicts Self-Reported Musculoskeletal Injury Severity in Norwegian Army Recruits.

INTRODUCTION: Non-combat musculoskeletal injuries are a leading cause of limited duty and non-deployability during military service. During basic training, up to 60% of recruits sustain at least 1 injury, although estimates based on medical records likely underestimate the true burden. The Oslo Sports Trauma Research Center Questionnaire on Health Problems (OSTRC-H2) enables prospective capture of all health problems, including those not requiring medical attention. This study aimed to identify baseline risk factors for musculoskeletal injury severity during basic training in the Norwegian Armed Forces using prospectively collected self-reported data. MATERIALS AND METHODS: In this 6-week prospective cohort study, 1,521 Norwegian recruits undergoing basic training at 2 Norwegian military camps consented and were included. Weekly self-reported injury data were collected using the OSTRC-H2. 1,346 (66% men) provided at least 1 OSTRC-H2 questionnaire response. Recruits were categorized as having no injury, only minor injury, or at least 1 substantial injury. Baseline variables included anthropometrics, physical fitness measures, motivation, and training context. Associations between baseline factors and musculoskeletal injury severity were examined using univariate and multivariate ordinal logistic regression analyses, including sex-stratified models. RESULTS: Overall, 34% of recruits reported at least 1 substantial injury. Women had higher unadjusted odds of substantial injury than men (OR 1.67, 95% CI 1.28-2.19), but this association was not significant after adjustment. Recruits who remained injury-free demonstrated higher baseline aerobic fitness and strength. In univariate analyses, multiple fitness-related variables were associated with musculoskeletal injury severity; however, in the multivariate model, only military camp (OR 0.74, 95% CI 0.58-0.95; P = .019) and 3,000 m run time (OR 1.15 per minute slower, 95% CI 1.07-1.23; P < .001) remained independently associated. Sex-stratified analyses confirmed 3,000 m run time as a consistent predictor in both men and women. CONCLUSIONS: Aerobic fitness, as measured by 3,000 m run time, is the strongest independent predictor of musculoskeletal injury severity during basic training. Apparent sex differences in injury severity are largely explained by differences in baseline fitness rather than sex itself. These findings support the use of aerobic fitness for risk stratification and highlight the importance of both individual preparedness and organizational factors in injury prevention strategies.