The Effects of Force-Velocity Profile-Based Load Prescription on Muscle Power and Functional Performance in Velocity-Deficient Older Adults

Muscle power is essential for functional capacity in older adults and can be improved through power-focused resistance training (PRT). PRT adaptations are load- and velocity-specific, yet optimal load prescription remains unclear. As force and velocity capacities vary between individuals, this 12-week intervention compared two force-velocity (F-V) profile-guided loading strategies: training at loads matched versus not matched to the F-V deficit. F-V profiles of 80 adults ≥ 65 years were assessed on a pneumatic leg press, with maximal force (F0) and velocity (V0) expressed as z-scores relative to a younger reference group (n = 60, 20-35 years). A difference ≥ 1 between z-scores was considered indicative of a deficit, with the direction determining a force- or velocity-deficit profile. As force deficits were rare (n = 4), the intervention only included participants with a velocity deficit (n = 59), of whom 57 initiated the intervention. Participants were randomly assigned to train at loads matched to their deficit (individualized; IND) or at loads deliberately not matched to their deficit (non-individualized; NON-IND). Maximal power, F-V profile parameters and functional performance were assessed at baseline, 6 and 12 weeks. From baseline to 12 weeks, F0 increased more in NON-IND than IND (p = 0.040), while V0 increased more in IND than NON-IND (p = 0.009). Changes in power and functional performance did not differ between groups (all p ≥ 0.065). In velocity-deficient older adults, differences in F-V-guided load prescription led to distinct F-V adaptations but did not lead to differences in power or functional performance. Trial Registration: The study was registered at ClinicalTrials.gov (NCT06449716).