Effects of Continuous and Cluster-Set Configurations Performed to Failure on Performance and Physiological Responses...

This study compared the acute effects of continuous execution (CON) and two cluster-set configurations performed to momentary failure with high loads (~85% one-repetition maximum) on mechanical and physiological responses during the bench press and half squat. Twelve recreationally trained men completed three randomized, counterbalanced conditions: two using cluster sets of three repetitions with either 10 s (CS10) or 20 s (CS20) intra-set rest, and a control (CON) condition. In the bench press, CS10 did not significantly increase the number of repetitions compared with CON, while CS20 increased repetitions from 6.8 ± 1.6 to 11.4 ± 2.9 (p = 0.044). In the half-squat, the effect of cluster sets on repetitions was evident in both CS10 and CS20 compared with CON (18.3 ± 4.0 and 42.1 ± 7.7 vs. 10.6 ± 3.2 repetitions, respectively, p < 0.001). Set duration increased progressively with longer intra-set rest, particularly in the half squat, reaching in CS20, 90.7 ± 26.2 s and 344.6 ± 65.3 s (p < 0.001) in the bench press and half squat exercises, respectively. Mean heart rate (HR) in CS20 was higher in the half squat than the bench press (87.2% ± 4.9% vs. 70.4% ± 6.5% of max HR, p < 0.001), while blood lactate responses were also greater in half-squat compared with bench press (~8.5 vs. 5.5 mmol L^-1, p < 0.001), with values in CS20 reaching 10.8 ± 4.5 mmol L^-1. In summary, when sets are performed to momentary failure with high loads, CS10 provides only modest performance benefits, whereas CS20 markedly increases training volume, particularly in the half squat. The elevated cardiovascular and metabolic stress observed under CS20 reflects the substantially greater total work performed rather than an inherent effect of the cluster configuration.