Acute effects of different rest intervals between agonist-antagonist paired-sets in the neuromuscular system performance of young adults.

Introduction: The agonist-antagonist paired-sets (APS) is a resistance training that involves alternating between exercises for agonist/antagonist muscles of a joint, with little or no rest between then. There is evidence that APS is more strenuous than traditional methods, but evidence on the optimal RI between agonist-antagonist actions is unknown.

Objective: The aim of this study was to compare different rest intervals between agonist-antagonist actions during APS in young adults.

Method: Fifty healthy men (mean age 23.2 ± 2.8 years; 1.76 ± 0.1m height, 78.03 ± 8.1 kg) were included and performed three different agonist-antagonist paired-sets protocols separated by 72h, consisting of 4 sets of 10 repetitions. The protocols differed in terms of the rest interval between the knee flexion and extension movements: 0s (no rest); 60s and 120s. The rest intervals between exercise sets were standardized at 60s. Total work, peak torque, neuromuscular efficiency, surface EMG amplitude (sEMG, root mean square) and fatigue index obtained by processing of sEMG signal, were compared between rest intervals and exercise sets within each protocol.

Results: There were no significant differences between rest intervals for total work, peak torque and neuromuscular efficiency (P > 0.05), but significant differences were found for sEMG and fatigue (P < 0.01), in which the protocol with 60s interval resulted in greater fatigue.

Conclusion: We showed that peak torque, total work and neuromuscular efficiency were not different between RI. The 60s RI showed a lower sEMG and a greater muscle fatigue. Although there were no significant differences, the NME was higher in the 60s interval.