Increases in Musculoskeletal Diagnosis Rates Corresponding With the Transition to the Army Combat Fitness Test.

Introduction: Non-combat musculoskeletal (MSK) disorders are a major cause of morbidity in the U.S. Army. Physical fitness tests are required for training and readiness, but they may be accompanied by injury risks. The Army recently transitioned from the Army Physical Fitness Test (APFT) to the Army Combat Fitness Test (ACFT). We hypothesize that this transition in, and associated changes in individual and group training regimens are associated with increased MSK diagnoses.

Materials and methods: We conducted a retrospective review of recently enlisted active duty service members from 2016 to 2022 and analyzed the incidence of MSK diagnoses within the first 6 months of military service. The 3 cohorts were control APFT (2016-2019), COVID (2020-2021), and ACFT (April 2022-October 2022). Survival analyses were used to compare ACFT and COVID cohorts with the control APFT.

Results: We studied 13,228 males (control: 75%; COVID: 17%; ACFT: 9%) and 2,404 females (control: 74%; COVID: 17%; ACFT: 9%). Among men, the ACFT cohort elevated hazard ratios (HRs) for general acute MSK (HRadj: 1.60; 95% CI: 1.32, 1.95) and cumulative MSK conditions (HRadj: 1.79; 95% CI: 1.63, 1.97) compared to controls. Among women, the ACFT group also had elevated risk compared to controls, but not by as much as in men (acute MSK: HRadj: 1.34; 95% CI: 0.97, 1.85; cumulative: 1.36; 95% CI: 1.14, 1.62). Compared to the control group, the COVID group had reduced rates of cumulative MSK conditions (males, HRadj: 0.86, 95% CI: 0.79, 0.94; females: HRadj: 0.83, 95% CI: 0.73, 0.95) and non-statistically significant differences in acute MSK conditions (males, HRadj: 1.99, 95% CI: 0.83, 1.18; females, HRadj: 0.87, 95% CI: 0.66, 1.16). Within cohorts, the incidence rate for women was almost twice that of men for many MSK diagnoses, particularly for acute knee conditions (women, control group: 1.4%; men, control group: 0.5%) and acute back conditions (women, control group: 0.9%; men control group: 0.4%).

Discussion: Among new enlistees, risk for MSK conditions has fluctuated, likely in response to the introduction of the ACFT in April 2022 and to COVID lockdowns. Consistent with much prior research, women had much higher rates of MSK conditions than men, which might mask trends over time. Continued monitoring of MSK trends over time and practices around the ACFT is necessary to maximize force readiness and minimize overall MSK disorder burden.