Effect of citrulline on post-exercise rating of perceived exertion, muscle soreness, and blood lactate levels: A systematic review and meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 33308806 · doi:10.1016/j.jshs.2020.02.003
What was done
Authors conducted a systematic review and meta-analysis of randomized controlled trials examining the acute effects of citrulline supplements (L-citrulline or citrulline malate taken within 2 hours pre-exercise) in healthy individuals. Searches were conducted across PubMed, Web of Science, and ClinicalTrials.gov. A random-effects model was used to analyze primary outcomes (rating of perceived exertion [RPE] and muscle soreness) and secondary outcomes (blood lactate levels).
What was found
The meta-analysis included 13 articles with a total of 206 participants, most commonly using an 8 g citrulline malate dosage. Citrulline significantly reduced RPE (n = 7 studies, p = 0.03) and reduced muscle soreness at 24 hours post-exercise (n = 7 studies, p = 0.04). It did not significantly reduce muscle soreness at 48 hours (n = 6 studies, p = 0.25) or 72 hours post-exercise (n = 4 studies, p = 0.62), nor did it significantly lower blood lactate levels (n = 8 studies, p = 0.17). Point estimates, effect sizes, and confidence intervals were not reported in the abstract.
Why it matters
This review suggests acute pre-exercise citrulline malate can modestly decrease perceived exertion and next-day muscle soreness, though it does not clear blood lactate or resolve longer-term soreness.
Limits
The total sample size is small (206 participants across 13 trials, averaging ~16 per study). The abstract notes high variability in study design, exercise tests, and populations. Only acute pre-exercise supplementation was assessed, and numerical effect sizes were omitted from the abstract.
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