The Self-Selected Rest Interval Method Is Reliable to Elicit Postactivation Performance Enhancement in Strength-Trained Athletes

Background: Postactivation performance enhancement (PAPE) refers to acute, transient improvements in explosive motor performance after high-intensity conditioning activity (CA), when an appropriate recovery period is allowed. Although the self-selected recovery interval (SSI) can elicit PAPE effectively, its reliability has not yet been established, which is essential to determine whether this strategy can be applied consistently across training sessions and whether observed performance enhancements reflect true physiological responses rather than random variation. This study assessed the reliability of the SSI used by strength-trained athletes across 2 identical sessions conducted on different days to elicit PAPE. Hypothesis: Both magnitude of changes in performance (PAPE) and the SSI would be reproducible. Study Design: Nonrandomized, single-group, crossover design with repeated measures. Level of Evidence: Level 2. Methods: Thirteen strength-trained athletes completed 3 sessions after familiarization with countermovement jump (CMJ) testing and 1 repetition maximum (1RM) squat determination. Two experimental sessions involved a CA comprising squats at 87% 1RM, followed by CMJ testing after a self-selected recovery. In the control session, CMJ was assessed after a light warm-up and a recovery equivalent to average SSI. Baseline CMJ tests were conducted in all sessions. SSI durations were compared using paired t tests. A 2-way repeated-measures analysis of variance evaluated CMJ performance. Reliability of SSI and CA-induced CMJ changes was assessed using intraclass correlation coefficients (ICCs) and coefficient of variation. Results: No significant differences were found in SSI durations between experimental sessions 1 (EXP1) and 2 (EXP2). CMJ performance did not change significantly after the light warm-up in CON, but increased by 9.7% in EXP1 (35.61 ± 10.78 cm vs 39.06 ± 11.47 cm; effect size [ES] = 0.31; P < 0.001) and by 10.6% in EXP2 (35.67 ± 10.8 cm vs 39.44 ± 11.51 cm; ES = 0.34; P < 0.001). ΔCMJ showed excellent reliability (ICC = 0.997), while SSI duration showed good reliability (ICC = 0.868). Conclusion: The findings confirm that SSI is a reliable strategy for eliciting PAPE. Clinical Relevance: The reproducibility of SSIs supports their practical implementation in strength and power training to achieve consistent performance enhancements across sessions.