Scand J Med Sci Sports. 2021 Oct 7. doi: 10.1111/sms.14073. Online ahead of print.
ABSTRACT
This study aimed to determine the specific adaptations provoked by power-oriented resistance training using light (LL-PT, 40% 1-RM) vs. heavy (HL-PT, 80% 1-RM) loads in older adults. Using a randomized within-subject study design, 45 older adults (>65 years) completed an 8-week control period (CTR) followed by 12 weeks of unilateral LL-PT vs. HL-PT on a leg press. The 1-RM, theoretical force at zero velocity (F0 ), maximal unloaded velocity (V0 ), and maximal muscle power (Pmax ) were determined through a force-velocity relationship test. Isometrically, the rate of force development (RFD) and the corresponding muscle excitation of the knee extensor muscles were assessed. In addition, muscle cross-sectional area (CSA) and architecture of two quadriceps muscles were determined. Changes after CTR, LL-PT and HL-PT were compared using linear mixed models. HL-PT provoked greater improvements in 1-RM and F0 (effect size (ES)=0.55-0.68; p<0.001) than those observed after LL-PT (ES=0.27-0.47; p≤0.001) (post-hoc treatment effect, p≤0.057). By contrast, ES of changes in V0 were greater in LL-PT compared to HL-PT (ES=0.71, p<0.001 vs. ES=0.39, p<0.001), but this difference was not statistically significant. Both power training interventions elicited a moderate increase in Pmax (ES=0.65-0.69, p<0.001). Only LL-PT improved early RFD (i.e., ≤100 ms) and muscle excitation (ES=0.36-0.60, p<0.05). Increased CSA were noted after both power training programs (ES=0.13-0.35, p<0.035), whereas pennation angle increased only after HL-PT (ES=0.37, p=0.004). In conclusion, HL-PT seems to be more effective in improving the capability to generate large forces, whereas LL-PT appears to trigger greater gains in movement velocity in older adults. However, both interventions promoted similar increases in muscle power as well as muscle hypertrophy.
PMID:34618979 | DOI:10.1111/sms.14073
