Plain language summary
Caffeine is a well-documented ergogenic aid. Among the existing studies that have explored this topic, women are largely underrepresented in the data. The aim of this meta-analysis was to evaluate whether the ergogenic effects of caffeine on strength and endurance known to be true for men could also be extended to women. The analysis included studies that used women as participants and found caffeine to have a significant ergogenic effect on both endurance and strength. When a sub-group analysis differentiated between upper- and lower-body exercises independently, only upper-body performance was improved by caffeine ingestion. Based on the current literature, the authors conclude the ergogenic effects that were previously observed in men are also applicable to women. They suggest further investigation as to why the ergogenic effect differs between upper- and lower-body performance.
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.
Methodological quality
Jadad score
:
Not applicable
Allocation concealment
:
Not applicable
Metadata
Nutrition Evidence keywords
:
Women
