Sports Drinks for Rehydration, Amelioration of Fatigue, and Recovery from Exertion

Sports drinks have traditionally been formulated as carbohydrate-electrolyte beverages to support fluid replacement and energy provision during exercise. However, commercially available and experimentally tested formulations now include amino acids, proteins, phytochemicals, caffeine, menthol, ketone-related nutrients, and other functional ingredients intended to support thermoregulation, performance, or post-exercise recovery. This narrative review summarizes evidence on sports drinks and related functional beverages, with emphasis on hydration, gastric emptying and intestinal absorption, thermoregulation, biomarkers of hydration and recovery, and potential effects beyond hydration, including fatigue, muscle and organ damage, inflammation, and immune responses. Because available studies vary widely in population, exercise mode, environmental conditions, beverage composition, intake timing, and outcome measures, the evidence should be interpreted cautiously. A functional distinction is made between hydration-oriented carbohydrate-electrolyte beverages and beverages primarily designed for ergogenic or recovery-oriented purposes. Current evidence supports the practical value of appropriate fluid, electrolyte, and carbohydrate intake for maintaining hydration and exercise performance, whereas evidence for broader effects on inflammation, immunodepression, organ protection, and recovery remains context-dependent. Future studies should differentiate acute responses from longer-term adaptations, consider population-specific needs, and use standardized, context-appropriate biomarkers and ecologically valid protocols.