# Post-Activation Potentiation Enhancement Response of Two Complex Training Sequences
###### Abstract  
Background: This study aimed to examine the effects of two complex training sequences on acute post-activation potentiation enhancement in countermovement jump (CMJ) performance. Methods: Twenty-two recreationally active males performed CMJ before and 1, 4, and 8 min after two sequences of complex training conducted in reverse order, consisting of a heavy load comprising three sets of squats with a 15% velocity-loss and three sets of maximal CMJ with a 10% height-loss for the low load. Results: No significant differences (\(p>0.05\)) were observed in the interaction time \(\times\) condition in CMJ variables. At the individual level, 23, 9, and 32% of participants improved CMJ performance in the high loads-low loads sequence at 1, 4, and 8 min compared to the baseline, respectively. In comparison, 14%, 23%, and 27% of participants improved CMJ performance in the light loads-high loads sequence. Eight participants in each sequence did not improve CMJ performance at any time, although these participants were not the same in both sequences. Conclusions: Stronger athletes (1.65 \(\pm\) 0.28 relative force) seemed to benefit more from the high loads-low loads sequence. In conclusion, there were no non-responders, as all the participants improved at some time point. The strength levels may be one of the moderating variables. p <concept> <concept  
muscle filaments behavior occurs due to the action of two proteins (actin and myosin) [7]. For these proteins to function, calcium molecules need to bind to them. According to [PERSON] and [PERSON] [7], performing a PAPE protocol enhances calcium sensitivity in the actin-myosin complex and therefore a higher performance. Therefore, PAPE has been introduced in many athletes' warm-up protocols worldwide, and is scientifically evidenced to improve sprint performance, jumping capacity, and other power-related movements compared to traditional warm ups [8]. In addition, PAPE effect has been significant not only in athletic populations across various sports but also in recreationally active populations [9; 10]. However, there is a large individual variability in PAPE response. This variability is mainly due to how individuals of different strength levels respond to the components of the force-power-potentiation complex [11]. Another factor is the fatigue threshold, i.e., the net balance between fatigue and potentiation (the relationship between fatigue and potentiation is thought to be influenced by individual characteristics) [12]. The prolonged acute effects after CPX as a conditioning activity have been analyzed, revealing that differences with other types of training have been seen in 1 RM squat, counter-movement jump (CM)), sprint, and change in direction performance [1; 11]. The acute effects of PAPE have been previously analyzed in different training sequences, including CPX training, where it has been found that this type of training enhances jump height and peak power compared to baseline when the fatigue from the training itself has disappeared [11]. However, to the best of our knowledge, most studies have not considered indicators of fatigue apart from performance enhancement during training execution. In most studies, intensity and volume are not individualized (using movement velocity and velocity loss). Consequently, training variables are not standardized, and training responses could differ between individuals [13]. One of the moderators influencing the PAPE response is the strength level of participants [11; 14], which may be responsible for the high variability in response found in the literature. The theoretical metabolic effects of CPX sequences have been analyzed in other studies offering controversial results [11]. In the case of HL-LL, scientific evidence has found a decrease in performance because the high loads performed at the beginning may produce fatigue that masks the PAPE effect, even though it dissipates more slowly [15].