Musculoskeletal Injuries During the Application Year Among Infantry Lieutenants: A Retrospective Observational Study

Infantry lieutenants complete an intensive Application Division (DA) training year combining theoretical instruction, practical exercises, and physically demanding activities. This study aimed to characterize the incidence and clinical and operational characteristics of musculoskeletal injuries (MSKIs) in this population.

This retrospective observational study included all French infantry lieutenants from the 2021 to 2023 cohorts at the Infantry Application Division School, Draguignan Military Schools. Data were extracted from AXONE, the national electronic medical record system of the French Armed Forces. Collected variables included demographic characteristics, prior MSKI history, injury type, anatomical location, circumstances of occurrence, and functional consequences. Injury incidence rates were calculated per 1,000 training days, assuming 6 days of training per week. Associations between injury occurrence and training phase or prior MSKI history (<3 years) were analyzed using McNemar's test and Fisher's exact test, respectively (P < .05).

A total of 384 lieutenants were included (99% male, mean age 28 ± 5 years, mean BMI 24 ± 2 kg/m2). Overall, 169 MSKIs were recorded, corresponding to an incidence of 1.14 injuries per 1,000 training days; 32 lieutenants sustained more than 1 injury. Most injuries occurred during the common training phase (59%) and were primarily associated with supervised physical training sessions (32%), toughening-up training (21%), and overseas field exercise in Djibouti (19%). The lower limbs were predominantly affected (62%). Most injuries were minor (wounds, sprains, contusions) and resulted in temporary sports incapacity (69%). A recent MSKI history (<3 years) was not associated with injury occurrence (P = .7). Four lieutenants required postponement of the DA year because of severe injuries or medical complications.

MSKIs during the DA year were relatively infrequent and predominantly resulted in minimal functional impairment, with the common training phase representing a higher-risk period. Targeted injury prevention strategies during this phase may help reduce injury incidence and limit training disruption.