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Fuel selection and cycling endurance performance with ingestion of [13C]glucose: evidence for a carbohydrate dose response.

PMID 20299609 (2010): carbohydrate, carb — Time to exhaustion, Time-trial performance, Fat oxidation (study note for endurance athletes).

Last updated/Feb 23, 2026, 11:13 PM

Study note • PMID 20299609

Fuel selection and cycling endurance performance with ingestion of [13C]glucose: evidence for a carbohydrate dose response.

Journal of applied physiology (Bethesda, Md. : 1985)2010 • DOI 10.1152/japplphysiol.91394.2008
Evidence C56/100
Action 2: Consider

Worth trying if it fits your goal and context.

ELI5

In plain language

Endurance performance and fuel selection while ingesting glucose (15, 30, and 60 g/h) was studied in 12 cyclists during a 2-h constant-load ride [approximately 77% peak O2 uptake] followed… (controlled study; n=12 cyclists).

The abstract reports an association involving Time-trial performance (not necessarily causation). Treat this as a signal, not a guarantee; confirm methods and context in the full paper.

Takeaways

What the abstract suggests

  • Study question: Endurance performance and fuel selection while ingesting glucose (15, 30, and 60 g/h) was studied in 12 cyclists during a 2-h constant-load ride [approximately 77% peak O2 uptake] followed…
  • The abstract reports an association involving Time-trial performance (not necessarily causation).
  • Population: n=12 cyclists.
  • Protocol cues: abstract may omit dose/timing; use the full paper to replicate accurately.

Protocol

Protocol (as reported)

  • Intervention/exposure: carbohydrate, carb (vs placebo).
  • Dose/time/duration: abstract doesn’t include enough detail; use the full paper’s methods section.
  • Outcomes: Time to exhaustion, Time-trial performance, Fat oxidation.
  • 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=12 cyclists) working on fueling.
  • Athletes who can measure Time to exhaustion, Time-trial performance, Fat oxidation 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: controlled study (placebo-controlled).
  • Population: n=12 cyclists.
  • Comparator: placebo.
  • Outcomes measured: Time to exhaustion, Time-trial performance, Fat oxidation.
  • Source: PubMed PMID 20299609 (2010) — Journal of applied physiology (Bethesda, Md. : 1985).

Results excerpt

What the abstract reports

Thus ingestion of glucose at low rates improved cycling time trial performance in a dose-dependent manner.

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