Acute effects of an individually timed lower-limb post-activation performance enhancement protocol on 50 m front crawl performance and race kinematics in national-level swimmers.

内容摘要

Post-activation performance enhancement (PAPE) has been proposed as an acute strategy to improve explosive performance, yet its effects on sprint-swimming performance remain unclear, particularly when individualized recovery timing is considered. This study examined the acute effects of a lower-limb PAPE protocol, applied using an individually determined recovery time (IRT), on 50&#xa0;m front crawl performance and selected start-, race-, and turn-related kinematic variables in national-level male swimmers. Fourteen male national-level swimmers completed a randomized repeated-measures cross-over design comprising control (CON) and PAPE conditions. In the PAPE condition, swimmers performed a lower-limb conditioning protocol consisting of loaded lunge-position squats on a Keiser Squat machine, followed by a maximal 50&#xa0;m front crawl trial at the end of the IRT. In the CON condition, swimmers completed the same swimming trial without the conditioning stimulus. Lower-limb power output increased significantly after the conditioning activity and reached its highest mean value at 6&#xa0;min post-exercise (F4,52 = 97.14, p&#x2009;<&#x2009;0.001). However, the PAPE protocol did not significantly improve overall 50&#xa0;m performance (25.508&#x2009;&#xb1;&#x2009;0.856&#xa0;s vs. 25.529&#x2009;&#xb1;&#x2009;0.773&#xa0;s; mean difference&#x2009;=&#x2009;-&#x2009;0.021&#xa0;s, 95% CI: -0.148 to 0.107; p&#x2009;=&#x2009;0.731) or most start-related variables. The only significant effect was observed for turn time, which was lower in the PAPE condition than in CON (7.707&#x2009;&#xb1;&#x2009;0.251&#xa0;s vs. 7.771&#x2009;&#xb1;&#x2009;0.261&#xa0;s; mean difference&#x2009;=&#x2009;-&#x2009;0.064&#xa0;s, 95% CI: -0.126 to -&#x2009;0.001; p&#x2009;=&#x2009;0.046). Responder analysis revealed substantial inter-individual variability across outcomes. In conclusion, a lower-limb PAPE protocol applied using the IRT did not improve overall 50&#xa0;m front crawl performance in national-level male swimmers, although it produced a small improvement in turn time. These findings suggest that the effects of lower-limb PAPE in sprint swimming may be segment-specific rather than global, and that practical implementation should be individualized rather than applied uniformly across swimmers.