Musculoskeletal, Biomechanical, and Physiological Gender Differences in the US Military

The repeal of the Direct Ground Combat Assignment Rule has renewed focus on examining performance capabilities of female military personnel and their ability to occupy previously restricted military occupational specialties. Previous research has revealed female Soldiers suffer a greater proportion of musculoskeletal injuries compared to males, including a signicantly higher proportion of lower extremity, knee, and overuse injuries. Potential differences may also exist in musculoskeletal, biomechanical, and physiological characteristics between male and female Soldiers requiring implementation of gender-specic training in order to mitigate injury risk and enhance performance.

Purpose: To examine differences in musculoskeletal, biomechanical, and physiological characteristics in male and female Soldiers.

Methods: A total of 406 101st Airborne Division (Air Assault) Soldiers (348 male; 58 female) participated. Subjects underwent testing for exibility, isokinetic and isometric strength (percent body weight), single-leg balance, lower body biomechanics during a stop jump and drop landing, body composition, anaerobic power/ capacity, and aerobic capacity. Independent t tests assessed between-group comparisons.

Results: Women demonstrated signicantly greater exibility (P<.01-P<.001) and better balance (P.001) than men. Men demonstrated signicantly greater strength (P.001), aerobic capacity (47.5±7.6 vs 40.3±5.4 ml/kg/min, P<.001), anaerobic power (13.3±2.1 vs 9.5±1.7 W/kg, P<.001), and anaerobic capacity (7.8±1.0 vs 6.1±0.8 W/kg, P<.001) and lower body fat (20.1±7.5 vs 26.7±5.7 (%BF), P<.001). Women demonstrated signicantly greater hip exion and knee valgus at initial contact during both the stop jump and drop landing tasks and greater knee exion at initial contact during the drop landing task (P<.05-P<.001).

Conclusions: Gender differences exist in biomechanical, musculoskeletal, and physiological characteristics. Sex-specic interventions may aid in improving such characteristics to optimize physical readiness and decrease the injury risk during gender-neutral training, and decreasing between-sex variability in performance characteristics may result in enhanced overall unit readiness. Identication of sex-specic differences in injury patterns and characteristics should facilitate adjustments in training in order for both sexes to meet the gender- neutral occupational demands for physically demanding military occupational specialties.