The Claim

Acute supplementation with 0.15 g/kg L-arginine and 0.1 g/kg citrulline malate has no significant effect on aerobic endurance, anaerobic power output, or CrossFit performance in healthy, trained men.

Source: Acute effects of combined supplementation of L-arginine and citrulline malate on aerobic, anaerobic, and CrossFit exercise performance

What the research says

Supports is higher

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

Supports
71score
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.

Quantitative
1 study reviewed
In plain English

Taking a single dose of 0.15 grams per kilogram of L-arginine and 0.1 grams per kilogram of citrulline malate does not improve aerobic endurance, anaerobic power, or CrossFit performance in healthy, trained men.

See the scientific wording

Acute supplementation with 0.15 g/kg L-arginine and 0.1 g/kg citrulline malate does not significantly improve aerobic endurance, anaerobic power output, or CrossFit performance in healthy, trained men, suggesting that this specific dosing regimen is unlikely to enhance exercise capacity in this population under acute conditions.

Why this might work

When taken together, L-arginine and citrulline malate increase the amount of arginine in the blood, which the body uses to make nitric oxide. Nitric oxide relaxes blood vessels, allowing more blood to flow to muscles. This should improve oxygen and nutrient delivery during exercise, but in trained men, this increased blood flow does not lead to better endurance, power, or performance in high-intensity workouts.

Supported mechanismbased on 1 study

What the research says

1 study
  1. Study: Acute effects of combined supplementation of L-arginine and citrulline malate on aerobic, anaerobic, and CrossFit exercise performance

    Taking this specific combo of supplements before a workout didn't make trained men stronger, faster, or more enduring in CrossFit, sprints, or cardio tests—except they got to their top speed a bit quicker on a bike, but didn't pedal harder or longer. So overall, the supplement didn't help much.

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

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