The Effect of Fluid Intake Following Dehydration on Subsequent Athletic and Cognitive Performance: a Systematic Review and Meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of controlled intervention trials
PubMed 28316054 · doi:10.1186/s40798-017-0079-y
What was done
A systematic review and meta-analysis examined the effect of fluid consumption following dehydration on subsequent athletic performance (continuous, intermittent, resistance, sport-specific, and balance) and cognitive performance. Databases (PubMed, Web of Science, Scopus) were searched for controlled trials comparing fluid intake to no fluid after dehydration. Meta-analysis was performed for continuous exercise performance.
What was found
Sixty-four trials across 42 publications (n = 643 participants) were reviewed. Prior dehydration reduced body mass by 1.3% to 4.2%, and fluid rehydration ranged from 0.4 to 1.55 L·kg⁻¹ body mass lost. Fluid intake significantly improved continuous exercise performance (22 trials; Hedges' g = 0.46, 95% CI 0.32, 0.61), with larger improvements seen in hotter environments and longer durations. Volume and timing of intake did not alter this effect. Evidence of benefit was less apparent for intermittent (10 trials), resistance (9 trials), sport-specific (6 trials), and balance (2 trials) exercise, as well as cognitive performance (15 trials).
Why it matters
Post-dehydration fluid consumption provides a moderate, reliable performance benefit during continuous endurance exercise, especially in hot conditions, even without complete rehydration. Benefits for strength, intermittent exercise, and cognition remain unproven.
Limits
Meta-analysis was limited to continuous exercise due to disparate outcome measures across other modalities. Individual trials had very small sample sizes (averaging ~10 participants per trial). Demographics such as sex, age, and fitness levels were not reported in the abstract.
Cited by
- supports Even a slight degree of dehydration can impair cognitive and physical performance.