Study note • PMID 40964913
Caffeine enhances performance regardless of fueling strategy; however, high carbohydrate availability is associated with improved training speeds compared with ketogenic diet.
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: randomized trial.
- • 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
The purpose of this study was to confirm reduced training metrics previously associated with a ketogenic low-carbohydrate (CHO) high-fat diet (LCHF) and investigate their attenuation with caffeine supplementation. (randomized trial; elite athletes).
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: The purpose of this study was to confirm reduced training metrics previously associated with a ketogenic low-carbohydrate (CHO) high-fat diet (LCHF) and investigate their attenuation with caffeine supplementation.
- • The abstract reports an association involving Time-trial performance (not necessarily causation).
- • Population: elite athletes.
- • Protocol cues (title/abstract): 3 mg/kg • 3 weeks • 20 min • 14 km • 450 m.
Protocol
Protocol (as reported)
- • Intervention/exposure: caffeine (vs placebo).
- • Dose/time/duration cues in abstract/title: 3 mg/kg • 3 weeks • 20 min • 14 km • 450 m.
- • Outcomes: Time-trial performance, Time to exhaustion.
- • 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 (elite athletes) working on supplements.
- • Athletes who can measure Time-trial performance, Time to exhaustion 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: randomized trial (placebo-controlled).
- • Population: elite athletes.
- • Comparator: placebo.
- • Outcomes measured: Time-trial performance, Time to exhaustion.
- • Protocol cues mentioned: 3 mg/kg • 3 weeks • 20 min • 14 km • 450 m.
- • Source: PubMed PMID 40964913 (2025) — The British journal of nutrition.
Results excerpt
What the abstract reports
“Although LCHF athletes walked faster at baseline compared with HCHO (P = 0.049), the HCHO group improved by week 2 (P = 0.009) and week 3 (P = 0.007), whereas the LCHF group was significantly slower in Week 1 (P < 0.001) and…”
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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