Acute effects of resisted and assisted activation on 50-m freestyle swimming performance

Previous research has shown that resisted and assisted sprint training can acutely enhance sprint performance via post-activation performance enhancement (PAPE). However, whether PAPE induced by conditioning activities that closely resemble sport-specific movements occurs in aquatic environments remains unclear. This study investigated the acute effects of resisted and assisted swimming activation on 50-m freestyle performance. Thirteen male collegiate swimmers completed a randomized, counterbalanced, repeated-measures design involving three warm-up conditions: standard warm-up (SWU), resisted swimming activation (RSA; 10-m maximal sprint with 8% body-mass load), and assisted swimming activation (ASA; 40-m maximal sprint at 103% maximal velocity). Compared with the other warm-up protocols, RSA significantly reduced split times over 5–10 m (p = 0.017, ES = 0.061) and 15–20 m (p < 0.001, ES = 0.188), and was associated with greater stroke length at 15 m (p = 0.001, ES = 0.188) and higher swimming velocity (p = 0.026, ES = 0.148). In contrast, ASA significantly reduced split time over 30–35 m (p = 0.003, ES = 0.191), but resulted in lower stroke length (p < 0.010, ES = 0.151) and swimming velocity (p < 0.001, ES = 0.199) at 25 m compared with the other warm-up conditions. RSA appears to preferentially enhance early race performance, whereas ASA may facilitate mid-race speed maintenance with limited overall benefit.