The Effect of Fluid Intake Following Dehydration on Subsequent Athletic and Cognitive Performance: a Systematic Review and Meta-analysis.
BACKGROUND
The deleterious effects of dehydration on athletic and cognitive performance have been well documented. As such, dehydrated individuals are advised to consume fluid in volumes equivalent to 1.25 to 1.5 L kg-1body mass (BM) lost to restore body water content. However, individuals undertaking subsequent activity may have limited time to consume fluid. Within this context, the impact of fluid intake practices is unclear. This systematic review investigated the effect of fluid consumption following a period of dehydration on subsequent athletic and cognitive performance.


METHODS
PubMed (MEDLINE), Web of Science (via Thomas Reuters) and Scopus databases were searched for articles reporting on athletic (categorized as: continuous, intermittent, resistance, sport-specific and balance exercise) or cognitive performance following dehydration of participants under control (no fluid) and intervention (fluid intake) conditions. Meta-analytic procedures determined intervention efficacy for continuous exercise performance.


RESULTS
Sixty-four trials (n = 643 participants) derived from 42 publications were reviewed. Dehydration decreased BM by 1.3-4.2%, and fluid intake was equivalent to 0.4-1.55 L kg-1BM lost. Fluid intake significantly improved continuous exercise performance (22 trials), Hedges' g = 0.46, 95% CI 0.32, 0.61. Improvement was greatest when exercise was performed in hotter environments and over longer durations. The volume or timing of fluid consumption did not influence the magnitude of this effect. Evidence indicating a benefit of fluid intake on intermittent (10 trials), resistance (9 trials), sport-specific (6 trials) and balance (2 trials) exercise and on cognitive performance (15 trials) was less apparent and requires further elucidation.


CONCLUSIONS
Fluid consumption following dehydration may improve continuous exercise performance under heat stress conditions, even when the body water deficit is modest and fluid intake is inadequate for complete rehydration.
School of Allied Health Sciences and Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia. danielle.mccartney@griffithuni.edu.au.
Danielle
http://orcid.org/0000-0002-7783-5220
D
McCartney
School of Allied Health Sciences and Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia.
Ben
B
Desbrow
School of Allied Health Sciences and Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia.
Christopher
C
Irwin
Athletic; Cognitive; Dehydration; Fluid intake; Mood; Performance