Effects Of Different Cs Protocols On Neuromuscular Activation And Fatigue Levels During High-intensity Resistance Exercise With Blood Flow Restriction In Recreational Athletes

The neuromuscular activation response to high-intensity resistance exercise combined with blood flow restriction (BFR) has been shown to decrease in recreational athletes. The cluster set (CS), which incorporates intra-set rest periods, may alleviate neuromuscular fatigue and stimulate gains in muscle strength and power. However, the specific CS protocols that are most effective for achieving these outcomes remain unexplored. PURPOSE: To compare the effects of different CS protocols on neuromuscular activation and fatigue levels in recreational athletes performing high-intensity resistance exercise with BFR. METHODS: Fifteen resistance-trained male subjects (age:19.9 ± 2.4 yrs; body mass: 71.4 ± 10.4 kg, and height: 176.5 ± 4.9 cm) participated in a randomized, cross-over study. Following familiarization with protocol, participants performed a parallel back squat at 80% of their one-repetition maximum (1-RM) with BFR under two conditions: A) Cluster set A (CS-A): 5 sets of 8 repetitions with a 36-second rest after every 4 repetitions and a 90-second inter-set rest interval.; B) Cluster set B (CS-B): 5 sets of 8 repetitions with a 12-second rest after every 2 repetitions and a 90-second inter-set rest interval. Countermovement jump (CMJ) vertical jump height (VJH), relater peak power (RPP), blood lactate concentrations (BL), electromyography (EMG) of the dominant-leg, and rating of perceived exertion (RPE) were assessed at baseline (pre-exercise) and at 0, 4-, 8-, 12-, and 16-minutes post-exercise for each condition. RESULTS: No significant differences were observed between CS-A and CS-B in VJH, RPP, BL, EMG, and RPE at any time point (p > 0.05). Additionally, no significant changes (%) were detected in CS-B compared to baseline (p > 0.05). However, in the CS-A group, VJH and RPP showed increases at 0 min compared to baseline (10.3 ± 10.2%, p = 0.008, d = 0.48; 4.7 ± 4.3%, p = 0.005, d = 0.37, respectively). CONCLUSIONS: Longer intra-set rest intervals in cluster set training may provide better immediate performance benefits in neuromuscular activation during high-intensity resistance exercise with blood flow restriction.