Acute Kinetic and Kinematic Responses to Rest Redistribution With Heavier Loads in Resistance-Trained Men

Abstract

Chae, S, Bailey, CA, Hill, DW, McMullen, SM, Moses, SA, and Vingren, JL. Acute kinetic and kinematic responses to rest redistribution with heavier loads in resistance-trained men. J Strength Cond Res 37(5): 987–993, 2023—The purpose of this study was to examine mechanical responses to rest redistribution with heavier loads (RR + L) in resistance-trained men. Eight men (23.0 ± 4.8 years, 1.76 ± 0.06 m, 78.5 ± 8.6 kg, back squat [BS] one-repetition maximum [1RM] of 138.7 ± 27.9 kg) completed 2 BS exercise sessions in a counterbalanced and a randomized order; RR + L: 4 sets of (2 × 5) repetitions with 90-second interset rest and 30-second intraset rest using 75% BS 1RM and traditional sets (TS): 4 sets of 10 repetitions with 120-second interset rest using 70% BS 1RM. During the concentric phase, mean force ($\overline{\text{x}}\text{F}$), velocity ($\overline{\text{x}}\text{V}$), and power ($\overline{\text{x}}\text{P}$) were collected for each repetition using a linear position transducer and analyzed the first 3 sets. Compared with TS, RR + L resulted in significantly greater $\overline{\text{x}}\text{F}$ (1820 ± 260 N vs. 1753 ± 248 N; p < 0.001; g = 0.25) and lower $\overline{\text{x}}\text{V}$ (0.47 ± 0.07 m·s⁻¹ vs. 0.50 ± 0.09 m·s⁻¹; p = 0.005; g = −0.35). However, no significant difference in $\overline{\text{x}}\text{P}$ (836 ± 165 W vs. 871 ± 197 W; p = 0.082; g = −0.18) was found between RR + L and TS. In conclusion, the lack of difference in $\overline{\text{x}}\text{P}$ might be the result of the combination of greater $\overline{\text{x}}\text{F}$ and lower $\overline{\text{x}}\text{V}$ for RR + L compared with TS. Therefore, practitioners may consider using RR + L to augment $\overline{\text{x}}\text{F}$ without compromising $\overline{\text{x}}\text{P}$ and increasing total rest time. However, given the approximate 4% difference in $\overline{\text{x}}\text{F}$, the effect of RR + L training on chronic strength adaptation is expected to be small.