The Claim

Multiple studies, including the present one, have failed to demonstrate consistent benefits of L-citrulline supplementation on endurance performance across varying dosages and durations.

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.

Description
1 study reviewed
In plain English

L-citrulline supplements do not consistently improve endurance performance, based on multiple studies that tested different doses and lengths of use.

See the scientific wording

The ergogenic potential of L-citrulline for endurance performance remains unconfirmed, as multiple studies—including this one—have failed to demonstrate consistent benefits despite varying dosages and durations.

Why this might work

L-citrulline is turned into arginine in the kidneys, which is then used to make nitric oxide in blood vessel walls. Nitric oxide relaxes the muscles around blood vessels, making them wider to increase blood flow. This should deliver more oxygen to muscles during exercise, but in practice, this does not improve how long a person can exercise.

Hypothetical 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 people L-citrulline pills for 10 days and had them exercise until exhaustion, but they didn’t last any longer than when they took a sugar pill. So, it doesn’t look like L-citrulline helps people run or 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.