Abstract
The main goal of the present study was to examine the effects of a high-velocity resistance training (HVRT) program on the force–velocity (F–V) profile of different groups of aging adults. An additional aim was to explore whether individual baseline F–V profiles were associated with training-induced improvements in muscle power and functional capacity. Middle-aged and older adults with and without mobility limitations ( n = 36, 61 ± 13 years) completed a 12-week HVRT program (2 days/week, 40–60% 1-RM). F–V profiles were determined using leg press exercises at loads ranging from 30–90% 1-RM, and a linear position transducer. Functional capacity was assessed via maximal gait speed and 30-s Sit-to-Stand tests. HVRT significantly increased the theoretical maximal force (F 0 ), maximal power (P max ), and the F–V slope (all p < 0.001), while maximal movement velocity (V 0 ) remained unchanged at the group level. Analysis of individual trajectories revealed substantial heterogeneity in F-V adaptations. Lower baseline V 0 was associated with greater improvements in V 0 (r = -0.629, p < 0.001), and this association was attenuated in an Oldham-style sensitivity analysis (r = -0.366, p = 0.028). Stratification by V 0 tertiles showed that velocity-deficient individuals had lower baseline power but experienced the greatest V 0 gains (+ 10.6% vs. -1.0%, p = 0.002). Within this subgroup, improvements in V 0 were associated with improvements in maximal gait speed (r = 0.685, p = 0.010). These findings suggest that, in the present sample, HVRT enhances muscle power primarily via force-related adaptations, while velocity-related adaptations were heterogeneous and may be functionally relevant when they occur.