Effectiveness of acute L-arginine supplementation on physical performance in strength training: a systematic review and meta-analysis

<p><span>The oral administration of L-arginine has been related to improved physical performance due to a likely reduction in muscle fatigue, resulting from the vasodilator effect of nitric oxide on skeletal muscle. However, there is no precise and quantitative analysis of the information in the literature. </span>Objective:<span> The main objective was to assess the effectiveness of L-arginine supplementation on physical performance in strength training with a systematic review and meta-analysis. Methods: Systematic review and meta-analysis, the PRISMA® (Preferred Reporting Items for Systematic Reviews and Meta-Analysis), PICOS statement and methodology guidelines, the quality of evidence by Classification of Assessment, Development and Assessment Recommendations (GRADE), Multiple Systematic Review Tool Assessment (AMSTAR2)</span><span>, and to assess the risk of bias of randomized clinical trials, the RoB 2.0 tool (Risk of Bias - Cochrane risk of bias tool revised for randomized trials)</span><span>. </span><span>The inclusion process established articles with well-designed human experiments that included only L-arginine supplementation testing the effects of L-arginine supplementation on sports performance related to strength training; identical experimental conditions in placebo or control group; and publications in the last ten years (until December 31, 2020). Three studies were included that compared L-arginine supplementation with placebo in anaerobic performance tests. </span>Results:<span> There was no significant heterogeneity (p&gt;0.05) in the analysis of the three selected articles and the effects of L-arginine supplementation in muscular endurance; performance had a mean of 0.26 (95% CI = -0.129; 0.649; p = 0.190), peak torque with a mean of -0.002 (95% CI = -0.531; 0.527; p = 0. 99) of the third series of exercises and, furthermore, when comparing the integrated effect (resistance rate with the peak torque) there was no difference with a mean of 0.168 (95% CI = -0.145; 0.481; p = 0.292). </span></p> <p>Conclusions:<span> Acute L-arginine supplementation provides no ergogenic effect on strength training performance.</span></p>