The Claim

A 10-day supplementation with 100 mg/kg/day of L-citrulline has no effect on time to exhaustion during high-intensity cycling at 75% of maximal power output in healthy, moderately active adults aged 18–35.

Source: Ergogenic effects of a 10-day L-citrulline supplementation on time to exhaustion and cardiorespiratory and metabolic responses in healthy individuals: a double-blind, randomised, placebo-controlled crossover trial

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
67score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

Cause and effect
1 study reviewed
In plain English

Taking L-citrulline for 10 days at a dose of 100 mg per kilogram of body weight does not change how long healthy, moderately active adults aged 18–35 can cycle at 75% of their maximum power before becoming exhausted.

See the scientific wording

A 10-day supplementation with 100 mg/kg/day of L-citrulline does not improve time to exhaustion during high-intensity cycling at 75% of maximal power output in healthy, moderately active adults aged 18–35, indicating no ergogenic benefit for this specific endurance protocol under these conditions.

Why this might work

L-citrulline is converted into arginine, which the body uses to make nitric oxide, a molecule that widens blood vessels. This should improve blood flow and oxygen delivery to muscles during intense exercise, but in healthy adults, this does not result in more oxygen reaching the working muscles or longer exercise time.

Supported mechanismbased on 1 study

What the research says

1 study
  1. Study: Ergogenic effects of a 10-day L-citrulline supplementation on time to exhaustion and cardiorespiratory and metabolic responses in healthy individuals: a double-blind, randomised, placebo-controlled crossover trial

    This study gave young, healthy adults L-citrulline pills for 10 days and had them cycle until they were too tired to continue. They didn’t last any longer than when they took a sugar pill, so the supplement didn’t help them cycle longer.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

Fit Body Science verdict — we translate health claims into clear verdicts backed by peer-reviewed research.

Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.