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Study note

Impact of Ad Libitum Hydration on Muscle and Liver Damage and Electrolyte Balance in Ultra-Trail Events: A Heatmap Analysis of Biomarkers and Event Characteristics-A Pilot Study.

PMID 40001904 (2025): hydration, fluid — Time to exhaustion, Performance in heat, Cramp risk (study note for endurance athletes).

Updated Jul 22, 2026

Read the study note

Study note • PMID 40001904

Impact of Ad Libitum Hydration on Muscle and Liver Damage and Electrolyte Balance in Ultra-Trail Events: A Heatmap Analysis of Biomarkers and Event Characteristics-A Pilot Study.

Biology2025 • DOI 10.3390/biology14020136

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: pilot study.
  • 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

Ultra-trail events (UTs) pose significant challenges to maintaining hydration and electrolyte balance, with risks of dehydration (DH), overhydration (OH), exercise-associated hyponatremia (EAH), and exertional rhabdomyolysis (ER). (pilot study; trained athletes).

The abstract doesn’t indicate a clear change in Time to exhaustion, Performance in heat, Cramp risk 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: Ultra-trail events (UTs) pose significant challenges to maintaining hydration and electrolyte balance, with risks of dehydration (DH), overhydration (OH), exercise-associated hyponatremia (EAH), and exertional rhabdomyolysis (ER).
  • The abstract doesn’t indicate a clear change in Time to exhaustion, Performance in heat, Cramp risk under the tested conditions.
  • Population: trained athletes.
  • Protocol cues (title/abstract): 48 h • 635 km • 586 m.

Protocol

Protocol (as reported)

  • Intervention/exposure: hydration, fluid.
  • Dose/time/duration cues in abstract/title: 48 h • 635 km • 586 m.
  • 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 (trained athletes) 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: pilot study.
  • Population: trained athletes.
  • Outcomes measured: Time to exhaustion, Performance in heat, Cramp risk.
  • Protocol cues mentioned: 48 h • 635 km • 586 m.
  • Source: PubMed PMID 40001904 (2025) — Biology.

Results excerpt

What the abstract reports

Four highly trained male athletes participated.

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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