Behavioral exercise motivation is more associated with ACFT success than body composition in collegiate Army ROTC cadets

Abstract

Objectives: Reserve Officers’ Training Corps (ROTC) cadets face unique physical demands due to structured military-style training, which may predispose them to musculoskeletal injury. However, concurrent evaluation of cadets’ musculotendinous structure, neuromuscular function, and behavioral factors such as sleep and exercise motivation is limited. Therefore, the primary purpose of this investigation was to compare musculotendinous morphology, tendon mechanics, and neuromuscular characteristics between ROTC cadets and physically active, non-military controls. A secondary investigative purpose was to assess whether body composition and motivation were associated with Army Combat Fitness Test (ACFT) performance within cadets. Methods: Thirty-four ROTC cadets (n=5 females; n=29 males) and 34 sex-, age-, and body mass-matched controls completed questionnaires on training habits, injury history, sleep (PSQI), and exercise motivation (BREQ-3), followed by body composition assessment, diagnostic ultrasonography of the medial gastrocnemius and Achilles tendon, and isometric plantarflexion force testing. Independent t-tests compared group means, and Pearson’s bivariate correlations were used within the ROTC group to assess relationships between Achilles tendon properties and sleep quality, as well as between exercise motivation, body composition, and ACFT performance, with significance set at α = 0.050. Results: Cadets presented greater weekly exercise volume and increased Achilles tendon stiffness compared to controls (all p≤0.004; d≥0.71), despite reduced gastrocnemius muscle volume, shorter fascicle lengths, and lower plantarflexion force (all p≤0.039; d≥0.43). Within cadets, poorer sleep quality was moderately associated with increased tendon stiffness and reduced echogenicity (all r≥.400; p≤0.046), while intrinsic exercise motivation (r=.693; p=0.001), but not body composition (all r≤0.211; p ≥0.371), showed moderate positive correlations with ACFT performance. Conclusions: ROTC cadets demonstrated higher tendon thickness coinciding with lower muscle volume and force production, suggesting potential increased musculotendinous injury risk. Additionally, intrinsic motivation, rather than body composition, showed stronger associations with ACFT performance. These findings highlight the importance of evaluating both physical and behavioral traits to better understand readiness and injury susceptibility in tactical populations.Lew Wentz FoundationKinesiology, Applied Health, and Recreatio