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

Background: 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. The main objective of this study was to assess the effectiveness of L-arginine supplementation on physical performance in strength training with a systematic review and meta-analysis. We hypothesized that L-arginine supplementation would improve performance capacity and the effects involved in strength training. Methods: The study period was from 2010 to 2020. The inclusion process established articles with well-designed human experiments that included only L-arginine supplementation (without any additional compounds) 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. Test analysis supplementation with other supplements was removed and there was no gender, age, and ethnicity level. Results: There was no significant heterogeneity (p>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). Conclusions: Acute L-arginine supplementation provides no ergogenic effect on strength training performance.