Effect of resistance training volume on heart rate variability in young adults

BACKGROUND: The volume in resistance training (RT) perhaps improve the autonomic modulation cardiac in untrained adults. OBJECTIVE: The aim was to analyze the effect of RT volume on heart rate variability (HRV) in young adults. METHODS: The intervention order was randomized and counterbalanced. Participants (n = 27) performed 1, 3 or 5 sets of the same exercises with equalized intensity (loading zones) and rested for eight weeks following eight weeks of washout between each experimental condition (1 vs. 3 vs. 5 sets). The researchers assessed HRV by cardiac monitoring seventy-two hours, both before (pre) and after (post) each experimental RT condition (1 vs. 3 vs. 5 sets). Factorial repeated measures ANOVA 2 x 3 were used to analyze the interaction between time (pre vs. post) and intervention (1 set vs. 3 sets vs. 5 sets) for the HRV index (RMSSD, SDNN, and pNN50). RESULTS: An interaction was identified between time and condition for RMSSD (F-(5,F-22) = 37.02, p < 0.01), SDNN (F-(5,F-22) = 32.80, p < 0.01), and pNN50 (F-(5,F-22) = 29.92, p < 0.02). Five set conditions (p = 0.01) showed improvement in HRV indicators when compared to one set and three set conditions. CONCLUSION: The study concluded that 5 set conditions improved HRV in young untrained adults.