From Populations to Programming Variables: Post-Activation Performance Enhancement Following Isometric Contractions...

Isometric contraction (ISO) has emerged as a potentially effective conditioning activity (CA) for inducing post-activation performance enhancement (PAPE). However, findings regarding its effects on subsequent muscular strength and power remain inconsistent, and the participant- and protocol-related characteristics associated with more favorable responses remain unclear. This systematic-review and meta-analysis aimed to evaluate the acute effects of ISO on subsequent muscular strength and power, compared ISO with control (CON) and dynamic isotonic contraction (DYN) conditions, and explore characteristics associated with more favorable PAPE. Twenty-five studies involving 782 participants were included. A three-level meta-analysis was used to account for dependent effect sizes, complemented by moderator analyses and meta-regression. For vertical jump height, ISO showed a significantly greater effect than CON (ES = 0.349, p < 0.01), whereas no significant difference was detected between ISO and DYN; a significant pre-post improvement was observed within the ISO group (ES = 0.180, p < 0.01). No significant within-ISO effect was observed for power output, and no significant effect was observed for muscular strength in either the within-ISO or ISO versus CON comparison. Moderator and meta-regression analyses suggested that some participant- and protocol-related conditions were associated with larger subgroup-specific effects on the vertical jump height, particularly 8-12 s contraction duration, 6-10 volume units, and 4-8 min of rest, although between-level differences were generally inconsistent. ISO appears effective for eliciting PAPE in vertical jump height, whereas current evidence for muscular strength and power remains limited. PROTOCOL REGISTRATION: The original protocol for the review was prospectively registered on PROSPERO (CRD42024608192).