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International society of sports nutrition position stand: caffeine and exercise performance.

PMID 33388079 (2021): altitude — VO₂max, Time-trial performance, Time to exhaustion (study note for endurance athletes).

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

Study note • PMID 33388079

International society of sports nutrition position stand: caffeine and exercise performance.

Journal of the International Society of Sports Nutrition2021 • DOI 10.1186/s12970-020-00383-4
Evidence C60/100
Action 2: Consider

Worth trying if it fits your goal and context.

ELI5

In plain language

Following critical evaluation of the available literature to date, The International Society of Sports Nutrition (ISSN) position regarding caffeine intake is as follows: 1. (review; n=3 well-trained cyclists).

In this review, the abstract suggests a positive relationship with Time-trial performance. Treat this as a signal, not a guarantee; confirm methods and context in the full paper.

Takeaways

What the abstract suggests

  • Study question: Following critical evaluation of the available literature to date, The International Society of Sports Nutrition (ISSN) position regarding caffeine intake is as follows: 1.
  • In this review, the abstract suggests a positive relationship with Time-trial performance.
  • Population: n=3 well-trained cyclists.
  • Protocol cues (full paper): 200 mg/day • 1 mg • 300 mg • 10 mg/kg • 160 mg • 400 mg.

Protocol

Protocol (as reported)

  • Intervention/exposure: altitude.
  • Dose/time/duration cues found in the full paper: 200 mg/day • 1 mg • 300 mg • 10 mg/kg • 160 mg • 400 mg • 200 mg • 3 mg/kg.
  • Outcomes: VO₂max, Time-trial performance, Time to exhaustion.
  • 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 (n=3 well-trained cyclists) working on altitude.
  • Athletes who can measure VO₂max, Time-trial performance, Time to exhaustion 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: review (randomized, double-blind, placebo-controlled).
  • Population: n=3 well-trained cyclists.
  • Outcomes measured: VO₂max, Time-trial performance, Time to exhaustion.
  • Protocol cues mentioned: 6 mg/kg • 2 mg/kg • 9 mg/kg • 3-6 mg/kg • 3 to 6 mg/kg • 4-6 mg/kg • 60 min.
  • Source: PubMed PMID 33388079 (2021) — Journal of the International Society of Sports Nutrition.

Full paper

What the full paper adds

  • Design features (paper): randomized, double-blind, placebo-controlled.
  • Participants (paper): n=3 well-trained cyclists.
  • More protocol detail (paper): 200 mg/day • 1 mg • 300 mg • 10 mg/kg • 160 mg • 400 mg • 200 mg • 3 mg/kg.

Results excerpt

What the abstract reports

For example, as compared to caffeine capsules, caffeine chewing gums may require a shorter waiting time from consumption to the start of the exercise session.

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).
  • Reviews and consensus statements mix protocols and populations; recommendations may not match your exact constraints.
  • 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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