How Repeatable is PAPE Effect: The Impact of In-Season Isometric Squat Activation on Countermovement Jump Performance Enhancement in Professional Soccer Players

Abstract

Background The purpose of this study was to investigate whether the post-activation performance enhancement (PAPE) induced by isometric squat exercises conditioning activity (CA) on three days after a match would be repeatable and occur during training sessions over a 4-week period during the season among professional soccer players. Additionally, the study aimed to determine whether the magnitude of acute PAPE responses would correlate with match workload monitored by GPS kinematic data. Methods Fifteen professional soccer players (competing at the highest level in the Polish Ekstraklasa) participated in the study (mean age: 26.9 ± 4.2 years, body mass: 79.2 ± 6.5 kg, height: 182.1 ± 6.5 cm, experience in soccer training: 11.2 ± 4.2 years, experience in strength training: 10.5 ± 4.6 years, relative maximal strength in squat: 1.84 kg/body mass). Each participant performed one countermovement jump (CMJ) without arm swing about 2 minutes before and approximately 1 minute after one set of isometric squats as CA using the smith machine with a 5-second maximum voluntary isometric contraction at the end of the warm-up. Results A two-way ANOVA showed a statistically significant main effect of time, indicating an increase in CMJ height after CA compared to baseline (F = 11.268, p < 0.005, η²p = 0.446), post-hoc test indicated significant increase in CMJ height (Mean difference [MD]=-1.05 ± 0,3 cm; Cohen’s d= -0.222; pbonf = 0.005) post-CA compared to baseline. Although a main effect of session on CMJ height was noted (F = 2.876, p = 0.047, η²p = 0.17), no significant differences between sessions were found upon post-hoc analysis (F = 0.093, p = 0.963, η²p = 0.006). Spearman's rank correlation test, no statistically significant correlation was found between the percentage difference in acute PAPE responses and individual GPS data. Conclusions These results indicate a significant increase in CMJ height after isometric CA in each measurement session throughout the four-week season and no correlation between the magnitude of the acute PAPE responses and match workload monitored by GPS kinematic data.