Outcome
    Moderate Evidence

    L-Citrulline for Endurance Enhancement

    Citrulline malate may extend time to exhaustion and reduce soreness, but trials are heterogeneous.

    Overview

    Citrulline malate may extend time to exhaustion and reduce soreness, but trials are heterogeneous.

    Verdict

    Mixed evidence

    How It Works

    Enhanced nitric oxide-mediated blood flow and improved ammonia clearance through the urea cycle may delay fatigue.

    Dosing & Protocol

    Typical dose

    Recommended dose
    8 g citrulline malate 2:1 (≈6 g citrulline) taken 60 minutes pre-exercise
    Expected timeframe
    Acute (single session) or 1-2 weeks of loading

    Protocol

    dose
    8 g citrulline malate 2:1
    form
    Citrulline malate 2:1
    timing
    60 minutes pre-exercise; daily loading 7-15 days in some trials
    duration
    Acute per session or 1-2 weeks loading

    Evidence

    What the studies say

    Meta-analyses find small improvements in exercise performance, with the malate component and dose timing likely mattering. Several well-controlled trials report no benefit.

    Acute Effects of Citrulline Supplementation on High-Intensity Strength and Power Performance: A Systematic Review and Meta-Analysis

    Score: 7/10
    2019
    meta_analysis
    n=198

    Trexler ET, Persky AM, Ryan ED +3 more

    Acute citrulline supplementation produced a small but statistically significant improvement in high-intensity strength and power performance versus placebo.

    View source

    Safety

    Caveats

    MIXED verdict: meta-analyses show small, inconsistent endurance benefits — mainly high-intensity/repeated-effort, not steady-state. Avoid with nitrates/PDE5 inhibitors. Pregnancy data lacking — avoid.

    Less likely to help if

    Well-trained endurance athletes show the least benefit; steady-state aerobic performance largely unaffected

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