Background: Post-activation performance enhancement (PAPE) is an emerging strategy for optimizing pre-competition warm-up in elite swimming. However, substantial heterogeneity exists across studies due to inconsistent load standardization methodologies. Objective: This randomized controlled trial aimed to examine the acute effects of three PAPE training modalities, heavy resistance training (HRT), plyometric training (PLY), and complex training (COM), on swim start performance and lower body power in elite swimmers, utilizing session rating of perceived exertion (sRPE) for load equalization. Methods: Forty-seven first-class swimmers (mean age 21.21 ± 0.69 years; training experience 8.08 ± 0.91 years) were randomly allocated to control (n = 11), heavy resistance training (n = 11), plyometric training (n = 12), or complex training (n = 13) groups. All interventions were standardized to achieve equivalent session rating of perceived exertion-time load (sRPE-TL) of 70-80 arbitrary units. The primary outcome was 15-m swim start time (T15m). Secondary outcomes included force platform variables (peak horizontal force, average propulsive force, propulsive impulse, take-off velocity) and land-based power measures (countermovement jump height and peak power). Performance assessments were conducted at 3, 6, 9, and 12 min post-intervention across four separate testing sessions. Effect sizes were calculated using Cohen`s d for within-group pre-post comparisons. Results: Mixed-model ANOVA revealed significant group × time interactions for T15m (F (3,43) = 2.339, P = 0.024, n2p = 0.14), peak horizontal force (F (3,43) = 19.407, P < 0.001, n2p = 0.58), average propulsive force (F (3,43) = 7.005, P < 0.001, n2p = 0.33), propulsive impulse (F (3,43) = 21.777, P < 0.001, n2p = 0.60), take-off velocity (F (3,43) = 23.148, P < 0.001, n2p = 0.62), CMJ height (F (3,43) = 2.884, P = 0.032, n2p = 0.17), and peak power (F (3,43) = 10.188, P < 0.001, n2p = 0.42). COM induced the largest improvements compared to CON, with T15m decresing by 3.00% (ES = 1.79, P < 0.001), peak horizontal force increasing by 5.14% (ES = 4.95, P < 0.001), average propulsive force by 8.48% (ES = 1.71, P < 0.001), propulsive impulse by 8.57% (ES = 3.46, P < 0.001), and take-off velocity by 6.41% (ES = 3.06, P < 0.001). Distinct temporal profiles emerged: PLY peaked at 6 min, HRT sustained effects through 12 min, while COM demonstrated optimal windows at 9-12 min sRPE-TL standardization successfully eliminated between-group load variability (CV < 8%, F (2,33) = 1.23, P = 0.297). Conclusion: Under sRPE-TL-standardized conditions, complex training elicited greater PAPE responses, with distinct optimal time windows among modalities (PLY: 6 min; HRT: 12 min; COM: 9-12 min), supporting individualized pre-race warm-up programming.
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