The impact of repetition mechanics on the adaptations resulting from strength-, hypertrophy- and cluster-type resistance training

Abstract

Purpose: The purpose of this study was to examine the acute and chronic training responses to strength-, hypertrophy- and cluster-type resistance training.

Methods: Thirty-four trained males were assigned to a strength [STR: 4 × 6 repetitions, 85 % of one repetition maximum, (1RM), 900 s total rest], hypertrophy (HYP: 5 × 10 repetitions, 70 % 1RM, 360 s total rest), cluster 1 (CL-1: 4 × 6/1 repetitions, 85 % 1RM, 1400 s total rest), and cluster 2 (CL-2: 4 × 6/1 repetitions, 90 % 1RM, 1400 s total rest) regimens which were performed twice weekly for a 6-week period. Measurements were taken before, during and following the four workouts to investigate the acute training stimulus, whilst similar measurements were employed to examine the training effects before and after the intervention.

Results: The improvements in 1RM strength were significantly greater for the STR (12.09 ± 2.75 %; p < 0.05, d = 1.106) and CL-2 (13.20 ± 2.18 %; p < 0.001, d = 0.816) regimens than the HYP regimen (8.13 ± 2.54 %, d = 0.453). In terms of the acute responses, the STR and CL-2 workouts resulted in greater time under tension (TUT) and impulse generation in individual repetitions than the HYP workout (p < 0.05). Furthermore, the STR (+3.65 ± 2.54 mmol/L(-1)) and HYP (+6.02 ± 2.97 mmol/L(-1)) workouts resulted in significantly greater elevations in blood lactate concentration (p < 0.001) than the CL-1 and CL-2 workouts.

Conclusion: CL regimens produced similar strength improvements to STR regimens even when volume load was elevated (CL-2). The effectiveness of the STR and CL-2 regimens underlines the importance of high loads and impulse generation for strength development.

Keywords: Cluster; Hypertrophy; Lactate; Muscle activity; Rest interval.

Fig. 1

Schematic representation of the experimental groups and design. 6/1 denotes six repetitions performed as singles

Fig. 2

Pre- to post-training percentage changes in 1RM back-squat strength. Asterisks significant difference from the HYP regimen (p < 0.05)

Fig. 3

Pre- and post-workout values for blood lactate concentration (values are mean ± SD). Asterisks significant change from pre- to post-workout (p < 0.05), number sign significant difference from CL-1 and CL-2 (p < 0.01) and dagger significant difference from STR