Effect of velocity loss squat induced post-activation performance enhancement on lower limb explosive power in sprinters

Background This study aimed to identify the optimal velocity loss (VL) threshold during squats for inducing post-activation performance enhancement (PAPE) in track and field sprinters, with the goal of maximizing sprint performance. Methods Twenty-four sprinters performed squat-based PAPE protocols using 85% 1RM (1 Repetition Maximum) across four VL thresholds (5%, 10%, 15%, and 20%). The 30-m sprint and countermovement jump (CMJ) tests were administered at baseline and at 4, 8, 12, and 16 min post-intervention. Measurements included CMJ height, peak power, momentum, and the number of squats completed under each VL condition. Results The 5% VL condition led to significant improvements in 30-m sprint time at 4 min (F (1,47) = 7.292, P = 0.01, Cohen’s d = −0.777) and 8 min (F (1,47) = 4.603, P = 0.037, Cohen’s d = −0.615), along with increases in CMJ height (F (1,47) = 5.748, P = 0.021, Cohen’s d = 0.69), peak power (F (1,47) = 5.585, P = 0.022, Cohen’s d = 0.685), and momentum (F (1,47) = 6.462, P = 0.014, Cohen’s d = 0.715). Under the 10% VL condition, significant gains were observed in 4-min sprint performance (F (1,47) = 5.288, P = 0.026, Cohen’s d = −0.656) and CMJ peak power at 4 min (F (1,47) = 5.585, P = 0.014, Cohen’s d = 0.741) and 8 min (F (1,47) = 3.884, P = 0.022, Cohen’s d = 0.687). The number of squats performed was significantly lower at 5% VL compared to other thresholds (P 0.001). Conclusion A velocity loss threshold of 5% during squats at 85% 1RM elicits a significant PAPE effect by 4 min post-exercise, with the fewest required repetitions. For practical application, a recovery interval of 4–8 min is recommended to optimize training outcomes in sprinters.