Performance Science Lab
Hydration lab
Hydration is context dependent: heat, sweat rate, and sodium losses change the plan.
Start here
- • Avoid extremes: both dehydration and overhydration can ruin performance.
- • Use simple field rules: thirst + body mass trend + urine color, not panic.
- • Treat electrolytes as a tool for heavy sweaters, not a default for everyone.
Study library (reference)
Individual studies for deeper reading.
Rehydration during Endurance Exercise: Challenges, Research, Options, Methods.
PMID 33803421 (2021): hydration, fluid — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).
Proper Hydration During Ultra-endurance Activities.
PMID 30601394 (2019): hydration, sodium — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).
Water and electrolyte requirements for exercise.
PMID 10410838 (1999): hydration, fluid — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).
Considerations for ultra-endurance activities: part 2 - hydration.
PMID 30056755 (2019): hydration, sodium — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).
Hydration Status and Sodium Balance of Endurance Runners Consuming Postexercise Supplements of Varying Nutrient Content.
PMID 25811075 (2015): hydration, sodium — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).
Sodium supplementation has no effect on endurance performance during a cycling time-trial in cool conditions: a randomised cross-over trial.
PMID 23731903 (2013): hydration, sodium — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).
Hydration strategies, weight change and performance in a 161 km ultramarathon.
PMID 24950110 (2014): hydration, sodium — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).
Predicting Hydration Status Using Machine Learning Models From Physiological and Sweat Biomarkers During Endurance Exercise: A Single Case Study.
PMID 35749337 (2022): hydration, fluid — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).
Prospective Observational Study of Weight-based Assessment of Sodium Supplements on Ultramarathon Performance (WASSUP).
PMID 33594588 (2021): hydration, sodium — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).
Sodium Hyperhydration Improves Performance With No Change in Thermal and Cardiovascular Strain in Female Cyclists Exercising in the Heat Across the Menstrual Cycle.
PMID 39591960 (2025): hydration, fluid — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).
Ultra-endurance events in tropical environments and countermeasures to optimize performances and health.
PMID 31429600 (2019): hydration, sodium — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).
Effects of oral sodium supplementation on indices of thermoregulation in trained, endurance athletes.
PMID 25729305 (2015): hydration, fluid — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).
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Performance Science Lab
Research-backed protocols and evidence grades for endurance performance — built for athletes.
Rehydration during Endurance Exercise: Challenges, Re… (PMID 33803421)
PMID 33803421 (2021): hydration, fluid — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).
Proper Hydration During Ultra-endurance Activities. (PMID 30601394)
PMID 30601394 (2019): hydration, sodium — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).
Water and electrolyte requirements for exercise. (PMID 10410838)
PMID 10410838 (1999): hydration, fluid — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).
Considerations for ultra-endurance activities: part 2… (PMID 30056755)
PMID 30056755 (2019): hydration, sodium — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).
Hydration Status and Sodium Balance of Endurance Runn… (PMID 25811075)
PMID 25811075 (2015): hydration, sodium — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).