Study note • PMID 40139199
The Addition of Glycerol and Sodium Chloride to a Hyperhydration Protocol Does Not Improve Half-Marathon Time-Trial Performance in Trained Runners in Warm Conditions.
How to use this page
This note summarizes one study record. Check the participants, methods, results, and limitations before applying it to training.
- • Design signal: randomized trial.
- • Population relevance: athlete/trained context.
- • Consistency: single-study evidence.
- • Practical recommendation depends on tolerance, context, and whether it protects training consistency.
ELI5
In plain language
We examined the effect of glycerol- and sodium-induced hyperhydration on a field-based half-marathon in warm conditions. (randomized trial; n=13 runners).
The abstract doesn’t indicate a clear change in Performance in heat under the tested conditions. Treat this as a signal, not a guarantee; confirm methods and context in the full paper.
Takeaways
What the abstract suggests
- • Study question: We examined the effect of glycerol- and sodium-induced hyperhydration on a field-based half-marathon in warm conditions.
- • The abstract doesn’t indicate a clear change in Performance in heat under the tested conditions.
- • Population: n=13 runners.
- • Protocol cues (title/abstract): 60 minutes • 20 minutes.
Protocol
Protocol (as reported)
- • Intervention/exposure: hydration, fluid (vs comparison group).
- • Dose/time/duration cues in abstract/title: 60 minutes • 20 minutes.
- • Outcomes: Time to exhaustion, Performance in heat, Cramp risk.
- • Replication note: abstracts often omit adherence and timing; confirm details before changing training or supplementation.
Fit
Who it may help, and who should be cautious
Who it helps
- • Athletes similar to the study population (n=13 runners) working on hydration.
- • Athletes who can measure Time to exhaustion, Performance in heat, Cramp risk with a repeatable workout or time-trial effort.
Who should be cautious
- • If you have symptoms or conditions that make the intervention risky, get professional guidance.
- • If you’re near race day and can’t safely test, defer the experiment.
Methods
What the study actually did
- • Design: randomized trial.
- • Population: n=13 runners.
- • Comparator: comparison group.
- • Outcomes measured: Time to exhaustion, Performance in heat, Cramp risk.
- • Protocol cues mentioned: 60 minutes • 20 minutes.
- • Source: PubMed PMID 40139199 (2025) — International journal of sports physiology and performance.
Results excerpt
What the abstract reports
“HYP increased fluid retention compared with CON by 1189 mL, 95% CI 987-1391 (P < .001), and plasma volume by 9.0%, 95% CI 3.6-14.4 (P = .001).”
Note: excerpts are short; for full context, read the paper.
Limits
Limitations and bias
- • Abstract-only summaries can miss critical details (population, protocol, adherence, and context).
- • Single studies often don’t generalize to your event, history, and training load; treat results as a starting point.
- • If your context differs (elite vs recreational; cycling vs running), adjust expectations and be conservative.
- • This is performance information, not medical advice.
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