Muscle Synergy Analysis of Different PAPE Protocols on Side Kick Performance in Elite Sanda Athletes: A Repeated Measures Study

<b>Background:</b> Post-activation potentiation (PAPE) enhances athletic performance through brief, high-intensity reactivation and holds significant application value in competitive sports. As a core offensive and defensive technique in Sanda, the side kick demands exceptional neuromuscular coordination. However, current research on PAPE applications in specialized techniques for competitive sports remains limited. There is a lack of comparative analysis on neuromuscular activation characteristics of the side kick in high-level Sanda athletes across different PAPE protocols, and the optimal adaptation scheme remains unidentified. Muscle coordination analysis based on non-negative matrix factorization (NMF) offers an objective perspective to elucidate the neuromuscular control mechanisms underlying this technique, thereby addressing this research gap. <b>Methods:</b> Eighteen high-level Sanda athletes (National Level 1 or above) participated in a randomized crossover design, sequentially undergoing three PAPE protocols-ESG, RBG, and SQG-with 10-day intervals between each intervention. Using the Noraxon wireless surface electromyography system, high-speed cameras, and the MY JUMP APP, we simultaneously collected vertical jump height data at different time points (6, 8, 10 min) post-intervention, along with electromyography and kinematic data of the side kick movement 6 min post-intervention. The NMF algorithm was employed to extract muscle coordination features (activation weights, activation coefficients), and repeated measures ANOVA or Friedman tests were used to assess intergroup differences. <b>Results:</b> Vertical jump height was significantly higher in the ESG group than in the RBG group at 6, 8, and 10 min post-intervention (<i>p</i> < 0.05). At 6 min post-intervention, it was also significantly higher than in the SQG group (<i>p</i> < 0.05). SQG showed significantly higher ESG than RBG at 8 min post-intervention (<i>p</i> < 0.05), with no significant differences from the other two groups at 10 min. Regarding muscle coordination, ESG and SQG exhibited significantly higher right rectus femoris activation weights than RBG (<i>p</i> < 0.05); ESG's gluteus maximus and rectus femoris activation weights were significantly higher than RBG (<i>p</i> < 0.05), with generally longer activation durations across all synergistic modules compared to the other two groups. Although RBG's vastus lateralis and gluteus medius activation weights were significantly higher than some groups, this did not translate into overall performance advantages. <b>Conclusions:</b> Different PAPE protocols exert distinct effects on vertical jump height and muscle coordination patterns during side kicks in elite Sanda athletes. The combined electrical stimulation protocol, which combines the immediate and sustained effects of PAPE, effectively enhances key muscle activation weights and prolongs coordination module activation duration. It represents the optimal solution for optimizing neuromuscular activation characteristics during sidekicks.