Do Athletes Lose Soleus Strength Over the Course of a Season? Longitudinal Monitoring of Seated Plantar Flexion Maximum Voluntary Contraction Strength and Factors That Affect It in Australian Football Players.

Green, B, Pizzari, T, Schache, AG, Rio, EK, Evans, SCS, Cooper, S, and Murphy, MC. Do athletes lose soleus strength over the course of a season? Longitudinal monitoring of seated plantar flexion maximum voluntary contraction strength and factors that affect it in Australian football players. J Strength Cond Res XX(X): 000-000, 2026-The calf muscles are critical to dynamic lower-limb function in sports but are susceptible to injury. Despite its role in performance and injury, research has not evaluated soleus strength changes over the course of a season, or factors affecting it. Flexed-knee maximum plantar flexion strength was longitudinally monitored in state-league Australian footballers (2 Western Australian and 1 Victorian team) across 1-season at timepoints: preseason (T0), early in-season (T1), late in-season (T2). Generalized estimating equations evaluated strength outcomes over time (absolute, relative, asymmetry). Intrinsic factors (e.g., age, sex, injury history, sport exposure history, calf-focused resistance training) were analyzed to determine longitudinal associations with strength. Forty-one athletes (32 male, 9 female) were monitored across 210 strength measurements from T0 to T2. Absolute (T0 = 121.7 ± 27 kg; T1 = 135.2 ± 27.3 kg; T2 = 135.8 ± 25.9 kg) and relative (T0 = 1.51 ± 0.28 body mass [BM]; T1 = 1.69 ± 0.27 BM, T2 = 1.75 ± 0.26 BM) strength demonstrated longitudinal change (absolute: β = 19.33 kg, relative: β = 0.24 BM; p < 0.001). Reduced strength was associated with a recent calf injury history (relative and absolute: p < 0.001) and older age (p = 0.03). Lower strength (absolute: β = -23.53 kg, relative: β = -0.22 BM; p < 0.05) and larger asymmetry (β = 8.13 kg, p = 0.01) were detected in female athletes. Athletes can be expected to improve and maintain soleus capacity across seasonal periods. Athlete age, calf injury history, and sex can affect strength longitudinally. These findings may guide individualized prevention, performance, and postinjury benchmarking.