Different Cluster Sets Result In Similar Metabolic, Endocrine, And Perceptual Responses In Trained Men
The purpose of this study was to compare the kinematic, metabolic, endocrine, and perceptual responses of three back squat protocols with equal loads, number of repetitions, and total rest duration. Eight strength-trained men performed 36 back squats using 75% 1RM and 420 s of total rest during basic cluster sets of 4 (CS4), rest-redistribution sets of 4 (RR4), and rest-redistribution sets of 1 (RR1). Ratings of perceived exertion (RPE), blood lactate (La), mean velocity maintenance (MVM), and mean velocity loss (MVL) were measured during exercise. Total testosterone (TT), growth hormone (GH), cortisol (C), and sex-hormone binding globulin (SHBG) were measured before exercise and 15, 30, and 60 min post-exercise. There were no differences between protocols for MVM. However, MVL was less during RR1 compared to RR4 (p=0.032), and neither protocol was different than CS4. All protocols resulted in similar increases in RPE and La, which remained elevated up to 30 min post-exercise (p<0.05). In all protocols, GH increased and returned to baseline by 60 min post-exercise (p<0.05). At 60 min post-exercise, TT was less than all other time points (p<0.05). There were no main effects for time for SHBG or C. The data from this study show that different types of cluster set protocols can result in pro-anabolic physiological responses to resistance training. Additionally, coaches can redistribute rest periods without affecting perceived effort or metabolic and hormonal changes if the external load, number of repetitions, and total rest time are equalized.