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Pre-cooling alters pacing profiles resulting in no additional benefit to 20-km self-paced maximal cycling time-trial performance in heat acclimated endurance athletes.

PMID 40393849 (2025): heat acclimation, heat stress — Performance in heat, Time-trial performance (study note for endurance athletes).

Last updated/Feb 23, 2026, 10:34 PM

Study note • PMID 40393849

Pre-cooling alters pacing profiles resulting in no additional benefit to 20-km self-paced maximal cycling time-trial performance in heat acclimated endurance athletes.

Journal of science and medicine in sport2025 • DOI 10.1016/j.jsams.2025.05.003
Evidence B71/100
Action 1: Default

Low risk + high feasibility for most athletes.

ELI5

In plain language

To examine the effect of pre-cooling (PreC) on cycling time-trial (CTT) performance in heat, before and after heat acclimation (HA). (randomized trial; trained triathletes).

The abstract doesn’t indicate a clear change in Performance in heat, Time-trial performance 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: To examine the effect of pre-cooling (PreC) on cycling time-trial (CTT) performance in heat, before and after heat acclimation (HA).
  • The abstract doesn’t indicate a clear change in Performance in heat, Time-trial performance under the tested conditions.
  • Population: trained triathletes.
  • Protocol cues (title/abstract): 60 min • 30 min • 5 km.

Protocol

Protocol (as reported)

  • Intervention/exposure: heat acclimation, heat stress (vs comparison group).
  • Dose/time/duration cues in abstract/title: 60 min • 30 min • 5 km.
  • Outcomes: Performance in heat, Time-trial performance.
  • Replication note: abstracts often omit adherence and timing; confirm details before changing training or supplementation.

Fit

Who it helps, and who should skip it

Who it helps

  • Athletes similar to the study population (trained triathletes) working on heat.
  • Athletes who can measure Performance in heat, Time-trial performance with a repeatable workout or time-trial effort.

Who should skip

  • 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: trained triathletes.
  • Comparator: comparison group.
  • Outcomes measured: Performance in heat, Time-trial performance.
  • Protocol cues mentioned: 60 min • 30 min • 5 km.
  • Source: PubMed PMID 40393849 (2025) — Journal of science and medicine in sport.

Results excerpt

What the abstract reports

Split times were faster in the first 12.5 km of the CTT in PostHA+PreC but slower across the rest of the CTT compared to PostHA-CON (b = -1.224 [-2.196, -0.157]).

Note: excerpts are short; for full context, read the paper.

Limits

Limitations & 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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Sources