Ergogenic Effects of Acute Caffeine Intake on Muscular Endurance and Muscular Strength in Women: A Meta-Analysis

Jozo Grgic,Juan Del Coso

doi:10.3390/ijerph18115773

Abstract

This meta-analysis aimed to explore the effects of caffeine ingestion on muscular endurance and muscular strength in women. Five databases were searched to find relevant studies. A random-effects meta-analysis of standardized mean differences (SMD) was performed for data analysis. Subgroup meta-analyses explored the effects of caffeine on upper-body and lower-body muscular endurance and muscular strength. Eight crossover placebo-controlled studies were included in the review. In the main meta-analysis that considered data from all included studies, there was a significant ergogenic effect of caffeine on muscular endurance (SMD = 0.25; p = 0.027) and muscular strength (SMD = 0.18; p < 0.001). In a subgroup analysis that considered only upper-body exercises, there was a significant ergogenic effect of caffeine on muscular endurance (SMD = 0.20; p = 0.007) and muscular strength (SMD = 0.17; p < 0.001). In a subgroup analysis that considered only lower-body exercises, there was no significant difference between caffeine and placebo for muscular endurance (SMD = 0.43; p = 0.092) or muscular strength (SMD = 0.16; p = 0.109). The main finding of this meta-analysis is that caffeine ingestion has a significant ergogenic effect on muscular endurance and muscular strength in women. The effects reported in this analysis are similar to those previously observed in men and suggest that women may use caffeine supplementation as an ergogenic aid for muscular performance. Future research is needed to explore the effects of caffeine on lower-body muscular endurance and muscular strength in this population.

Highlights

IntroductionA recent umbrella review of 21 meta-analyses concluded that caffeine ingestion is ergogenic for various components of exercise performance [3]
The main finding of this meta-analysis is that caffeine ingestion is ergogenic for muscular endurance and muscular strength in women
The effectiveness of caffeine on these muscular qualities was categorized as small, even though it was similar to the effects previously reported in male participants

Summary

Introduction

A recent umbrella review of 21 meta-analyses concluded that caffeine ingestion is ergogenic for various components of exercise performance [3]. One limitation of the current body of evidence is that most primary studies are conducted among male participants. The prevalence of primary studies with male-only samples ranged from 72% to 100% across the 21 meta-analyses included in the umbrella review [3]. This finding is in accord with a recent commentary that summarized data from 362 studies examining the effects of caffeine on exercise performance and found that only

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