Postactivation potentiation effects on squat performance and muscle synergies in resistance trained men

Purpose Postactivation potentiation (PAP) is a practical strategy to improve acute performance. PAP consists of performing two consecutive exercises, an exercise of maximal or submaximal contraction, called conditioning activity (CA), followed by a similar movement pattern that requires a rapid expression of force. There is a lack of literature concerning the differences in muscle activation and muscle synergies during a resistance training exercise in resistance trained men in relation to PAP. Our study wants to investigate whether a relationship between PAP and NO-PAP effect exists, assessed by the tonnage beared. In addition, we want to analyze how the muscle activation and muscle synergy can affect the performance. Methods Were selected 8 resistance trained men. Following an initial evaluation of their one repetition maximum (1RM) of squat, each participant were randomly assigned at a PAP or NO-PAP group, were subjects used or didn’t use the CA before the resistance training protocol. After 72 hours, the participants assigned at the PAP group were instructed to perform a protocol with CA, which involved performing 1 set of 2 repetitions at 90% of 1RM. After 7 minutes of rest 3 sets at 70% of 1RM were carried out until concentric exhaustion with 2 minutes rest between sets. The EMG was recorded on the vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF), gluteus maximus (GM) and long head of biceps femoris (BF). The muscle activation were recorded by electromyography (EMG), instead the muscle synergies will be evaluated by non-negative matrix factorization (NNMF) algorithm. Results Preliminary data show that PAP induces higher neuromuscular activity in BF and GM during the resistance training protocol. Instead, RF, VL and VM revealed a decrease in muscle activation. Tonnage is higher in PAP group than NO-PAP group. The analysis of muscle synergies will be done in the future, but it’s possible speculate on them. Conclusions In the future, these data provide evidences of the necessity to assess the neuromuscular activity and muscle synergies in order to advance in understanding the PAP effect.