01/11/2026
🏃♂️💧 SPORTS NUTRITION EVIDENCE UPDATE
Two recent studies offer practical lessons for hydration monitoring and training in hot, humid conditions.
1️⃣ Portable saliva hydration testing
Direct-from-tongue readings from a portable saliva-osmolality device showed poor repeatability and weak agreement with laboratory testing.
✅ Practical takeaway: Do not prescribe fluid or sodium from one saliva reading. Combine pre-/post-session body mass, fluid intake, thirst, urine pattern, environmental conditions and the athlete’s sweat history.
Evidence strength: Early — only 20 active adults.
2️⃣ Heat, humidity and running output
Data from 91 international-level footballers indicated that high-speed running, acceleration and sprint distance declined as temperature increased under moderate-to-high humidity.
✅ Track application:
• Monitor WBGT or apparent temperature—not air temperature alone
• Schedule demanding sessions earlier
• Extend recovery between repetitions
• Provide shade and cold fluids
• Reduce total volume before sacrificing movement quality or intensity
Evidence strength: Early-to-moderate — a large elite dataset, but observational and football-specific.
📌 Bottom line: Measure the individual athlete rather than relying on one device, and manage humidity as well as temperature. Hydration and heat strategies should reflect workload, sweat loss, climate and personal tolerance.
📚 References:
Zhao et al. (2026): https://doi.org/10.1007/s00421-026-06476-3
Cormier et al. (2026): https://doi.org/10.1123/ijspp.2026-0057
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