Acute mechanical, physiological and perceptual responses in older men to traditional-set or different cluster-set configuration resistance training protocols

Purpose
The aims of this study were to compare mechanical outputs (i.e. power and impulse), physiological (i.e. heart rate), and perceptual (i.e. effort and fatigue) responses in older men to traditional-set or different cluster-set configuration resistance training protocols.
Methods
In a randomized cross-over design, twenty healthy old men (aged 67.2 ± 2.1 years) completed four resistance training sessions using the back squat exercise loaded with optimal power loads. Training configurations were: traditional (TRA), three sets of six repetitions with 120 s rest between each set; Cluster-set 1 (CLU1), 24 single-repetition clusters with 10 s of rest after every cluster; Cluster-set 2 (CLU2), 12 double repetition clusters with 20 s rest after every cluster; and Cluster-set 4 (CLU4), six quadruple-repetition clusters with 40 s rest after every cluster.
Results
Cluster-set configurations resulted in greater power outputs compared to traditional-set configuration (range: 2.6 to 9.2%, all p ≤ 0.07 for main effect and protocol × set interactions). CLU1 and CLU2 induced higher heart rate (range: 7.1 to 10.5%, all p < 0.001 for main effect and protocol × set interactions), lower rating of perceived exertion (range: -1.3 to -3.2 AU, all p ≤ 0.006 for pairwise comparisons) and lower ratings of fatigue (range: -0.15 to -4 AU, all p ≤ 0.012 for pairwise comparisons) compared to TRA and CLU4. Finally, an absolute preference for CLU2 was reported.
Conclusions
Findings presented here support the prescription of CLU2 as an optimal resistance training configuration for trained older men using the back squat.