High-speed vs. low-speed resistance training on muscle function in individuals with low muscle mass and obesity

Purpose: This study investigated the effects of high-speed (HSRT) and low-speed resistance training (LSRT) on muscle function in individuals with low muscle mass and obesity (LMO).MethodsSeventy-three participants (65.9 ± 5.8 years; 63 women and 10 men) were randomly assigned to the LSRT, HSRT, and control groups. Participants in the LSRT and HSRT groups received a 16-week resistance training intervention. LSRT and HSRT differed only in concentric speed (4 s vs. 1 s), while the eccentric phase was identical. The control group maintained usual lifestyles. Outcomes were assessed at baseline and after 16 weeks. The primary outcome was quadriceps isokinetic muscle power at 60°/s, 180°/s, and 240°/s. Secondary outcomes were quadriceps isometric and isokinetic muscle torque, rate of force development (RFD) during isometric contraction, muscle electrical activity during both isometric and isokinetic contractions, muscle endurance, and one-repetition maximum (1RM) of all training movements. Analysis of covariance examined between-group effects (α = 0.05).ResultsAfter the intervention, both LSRT and HSRT groups improved 1RM compared with the control group (p < 0.05), but not peak isometric torque. Only the HSRT group showed greater improvements than the control group in isokinetic muscle power (+19% at 180°/s and + 27% at 240°/s) and RFD (+59%) (all p < 0.05). Neither training group attenuated torque decline during the endurance test (p > 0.05).ConclusionsBoth LSRT and HSRT improved strength, but only HSRT enhanced isokinetic muscle power and RFD in adults with LMO. These findings suggest that incorporating HSRT may provide additional benefits for improving power-related outcomes in this population.