Study note • PMID 12381742
Effects of L-tyrosine and carbohydrate ingestion on endurance exercise performance.
Low risk + high feasibility for most athletes.
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 helps, and who should skip it
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 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: 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 & 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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