Study note • PMID 23846824
The use of carbohydrates during exercise as an ergogenic aid.
Worth trying if it fits your goal and context.
ELI5
In plain language
Carbohydrate and fat are the two primary fuel sources oxidized by skeletal muscle tissue during prolonged (endurance-type) exercise. (review; well-trained athletes).
In this review, the abstract doesn’t find a clear benefit for 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: Carbohydrate and fat are the two primary fuel sources oxidized by skeletal muscle tissue during prolonged (endurance-type) exercise.
- • In this review, the abstract doesn’t find a clear benefit for Time-trial performance.
- • Population: well-trained athletes.
- • Protocol cues (title/abstract): 2 h • 3 h • 2.5 h • 60 min • 24 h.
Protocol
Protocol (as reported)
- • Intervention/exposure: carbohydrate, carb.
- • Dose/time/duration cues in abstract/title: 2 h • 3 h • 2.5 h • 60 min • 24 h.
- • 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 (well-trained athletes) 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: review.
- • Population: well-trained athletes.
- • Outcomes measured: Time to exhaustion, Time-trial performance, Fat oxidation.
- • Protocol cues mentioned: 2 h • 3 h • 2.5 h • 60 min • 24 h.
- • Source: PubMed PMID 23846824 (2013) — Sports medicine (Auckland, N.Z.).
Results excerpt
What the abstract reports
“For those athletes with a lower gastrointestinal threshold for carbohydrate ingestion immediately post-exercise, and/or to support muscle re-conditioning, co-ingesting a small amount of protein (0.2-0.4 g.kg(-)(1).h(-)(1)) with less carbohydrate (0.8 g.kg(-)(1).h(-)(1)) may provide a feasible option to achieve similar muscle glycogen repletion rates.”
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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Performance Science Lab
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Time to exhaustion research for endurance athletes
A lab outcome that can still guide training: it often tracks fatigue resistance.
Time-trial performance research for endurance athletes
Practical performance outcome used in many studies: closer to racing than lab-only metrics.