Short rest interval lengths between sets optimally enhance body composition and performance with 8 weeks of strength resistance training in older men
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To determine if 8 weeks of periodized strength resistance training (RT) utilizing relatively short rest interval lengths (RI) in between sets (SS) would induce greater improvements in body composition and muscular performance, compared to the same RT program utilizing extended RI (SL).
22 male volunteers (SS: n = 11, 65.6 ± 3.4 years; SL: n = 11, 70.3 ± 4.9 years) were assigned to one of two strength RT groups, following 4 weeks of periodized hypertrophic RT (PHRT): strength RT with 60-s RI (SS) or strength RT with 4-min RI (SL). Prior to randomization, all 22 study participants trained 3 days/week, for 4 weeks, targeting hypertrophy; from week 4 to week 12, SS and SL followed the same periodized strength RT program for 8 weeks, with RI the only difference in their RT prescription.
Following PHRT, all study participants experienced increases in lean body mass (LBM) (p < 0.01), upper and lower body strength (p < 0.001), and dynamic power (p < 0.001), as well as decreases in percentage body fat (p < 0.05). Across the 8-week strength RT phase, SS experienced significantly greater increases in LBM (p = 0.001), flat machine bench press 1-RM (p < 0.001), bilateral leg press 1-RM (p < 0.001), narrow/neutral grip lat pulldown (p < 0.01), and Margaria stair-climbing power (p < 0.001), compared to SL.
This study suggests 8 weeks of periodized high-intensity strength RT with shortened RI induces significantly greater enhancements in body composition, muscular performance, and functional performance, compared to the same RT prescription with extended RI, in older men. Applied professionals may optimize certain RT-induced adaptations, by incorporating shortened RI.
KeywordsHypertrophy Maximal dynamic strength Sarcopenia Acute hormonal responses Physical function
Analysis of variance
Clinical Exercise Research Center
Coefficient of variance
Dual-energy X-ray absorptiometry
Lean body mass
Rest interval length in between sets
Star excursion balance test
The authors would like to thank the study participants, University of Southern California Clinical Exercise Research Center staff, and Adriana Del Padilla for their contribution to the successful completion of the experimental protocol. This study was funded by the National Strength and Conditioning Association Foundation (NSCAF). The results of the present study do not constitute endorsement by NSCA.
Conflict of interest
For all authors, there are no conflicts of interest, which might lead to bias in this manuscript.
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