Background: The development of muscular power is often a key focus of sports performance enhancement programs.
Objective: The purpose of this meta-analysis was to examine the effect of load on peak power during the squat, jump squat, power clean, and hang power clean, thus integrating the findings of various studies to provide the strength and conditioning professional with more reliable evidence upon which to base their program design.
Methods: A search of electronic databases [MEDLINE (SPORTDiscus), PubMed, Google Scholar, and Web of Science] was conducted to identify all publications up to 30 June 2014. Hedges' g (95% confidence interval) was estimated using a weighted random-effect model. A total of 27 studies with 468 subjects and 5766 effect sizes met the inclusion criterion and were included in the statistical analyses. Load in each study was labeled as one of three intensity zones: Zone 1 represented an average intensity ranging from 0 to 30% of one repetition maximum (1RM); Zone 2 between 30 and 70% of 1RM; and Zone 3 ≥70% of 1RM.
Results: These results showed different optimal loads for each exercise examined. Moderate loads (from >30 to <70% of 1RM) appear to provide the optimal load for power production in the squat exercise. Lighter loads (≤30% of 1RM) showed the highest peak power production in the jump squat. Heavier loads (≥70% of 1RM) resulted in greater peak power production in the power clean and hang power clean.
Conclusion: Our meta-analysis of results from the published literature provides evidence for exercise-specific optimal loads for power production.