Complex training and post-activation performance enhancement for strength improvement in football: A systematic review

Strength is a key physical quality in football, and multiple training approaches have been suggested to enhance it. Complex training (CT) is one such approach and is mechanistically linked to post-activation potentiation (PAP), whereby heavy conditioning contractions may increase motor-neuron excitability and augment subsequent force production. However, in applied sport settings, most reported improvements are more accurately explained by post-activation performance enhancement (PAPE), which reflects improvements in voluntary performance rather than twitch responses. This systematic review evaluated the effects of PAP/PAPE and CT on strength-related outcomes and performance in football players. In accordance with PRISMA guidelines, a structured literature search was conducted in Web of Science, Scopus, and PubMed to identify eligible studies published up to 28 January 2026. Methodological quality (risk of bias) was assessed using the PEDro scale. The search yielded 1585 records; after removing duplicates, titles and abstracts were screened, and full texts were evaluated against predefined inclusion and exclusion criteria. Thirty-four studies met the eligibility criteria and were included in the synthesis. Overall, the available evidence suggests that CT and PAPE can enhance strength-related performance in football players. CT appears applicable across different phases of the season, with beneficial findings reported in both pre-season and competitive microcycles. PAPE protocols also generated meaningful improvements in repeated-sprint ability, change of direction, countermovement jump, and sprint performance, most commonly when using loads of approximately 80–90% of 1RM in professional players.