Taking L-citrulline or L-arginine supplements doesn't seem to help competitive swimmers swim faster in 100m or 200m races, even though scientists thought these supplements might help by improving blood flow or reducing muscle burn.
Claim Language
Language Strength
probability
Uses probability language (may, likely, can)
The claim uses 'is not supported by evidence,' which indicates a lack of proof rather than absolute denial. This phrasing suggests uncertainty and falls under probability language, as it implies the possibility exists but is not confirmed, rather than definitively stating no effect.
Context Details
Domain
exercise_science
Population
human
Subject
L-citrulline or L-arginine supplementation
Action
is not supported by evidence
Target
ergogenic potential for swimming performance in trained athletes performing 100-m and 200-m events
Intervention Details
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.
Evidence from Studies
Supporting (1)
Eight Days of L-Citrulline or L-Arginine Supplementation Did Not Improve 200-m and 100-m Swimming Time Trials
Scientists gave swimmers either L-citrulline, L-arginine, or a placebo for 8 days and then timed them in 100m and 200m swims. The supplements didn’t make them swim any faster, so they don’t work as performance boosters for these events.