Study note • PMID 12381742
Effects of L-tyrosine and carbohydrate ingestion on endurance exercise performance.
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: mixed/unclear athlete specificity.
- • Consistency: single-study evidence.
- • Practical recommendation depends on tolerance, context, and whether it protects training consistency.
ELI5
In plain language
To test the effects of tyrosine ingestion with or without carbohydrate supplementation on endurance performance, nine competitive cyclists cycled at 70% peak oxygen uptake for 90 min under four… (randomized trial; cyclists).
The abstract doesn’t indicate a clear change in 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 test the effects of tyrosine ingestion with or without carbohydrate supplementation on endurance performance, nine competitive cyclists cycled at 70% peak oxygen uptake for 90 min under four…
- • The abstract doesn’t indicate a clear change in Time-trial performance under the tested conditions.
- • Population: cyclists.
- • Protocol cues (title/abstract): 25 mg/kg • 90 min • 60 min • 30 min • 15 min • 0.9 min.
Protocol
Protocol (as reported)
- • Intervention/exposure: carbohydrate, carb (vs placebo).
- • Dose/time/duration cues in abstract/title: 25 mg/kg • 90 min • 60 min • 30 min • 15 min • 0.9 min • 1.1 min • 2.9 min.
- • 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 may help, and who should be cautious
Who it helps
- • Athletes similar to the study population (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 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 (double-blind, placebo-controlled).
- • Population: cyclists.
- • Comparator: placebo.
- • Outcomes measured: Time to exhaustion, Time-trial performance, Fat oxidation.
- • Protocol cues mentioned: 25 mg/kg • 90 min • 60 min • 30 min • 15 min • 0.9 min • 1.1 min • 2.9 min.
- • Source: PubMed PMID 12381742 (2002) — Journal of applied physiology (Bethesda, Md. : 1985).
Results excerpt
What the abstract reports
“The plasma tyrosine-to-free tryptophan ratio was significantly higher in Tyr and CHO+Tyr vs.”
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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