Acute effect of caffeine consumption on isotonic muscular strength and endurance: A systematic review and meta-analysis

The aim of the present study was to perform a systematic review and meta-analysis of the acute effects of caffeine ingestion on maximal strength and muscular endurance in isotonic resistance exercises. Up until March 2015, 17 studies which met the inclusion criteria, 42 trials related to muscular endurance and 5 trials related to muscular strength, were found from a search in the following databases: PubMed, ISI Web of Knowledge, SportDiscus, Scielo, Lilacs, Medcarib, Ibecs and ProQuest Dissertations & Theses. The effect sizes were calculated as the standardized mean difference and meta-analysis were completed using a random-effects model. No significant effects were identified for gender, muscle location, muscle size, dosage of caffeine or form or timing of pre-exercise caffeine consumption on performance at maximum strength. For muscular endurance, all moderators were related to improve performance after caffeine intake (P