The effect of l-arginine supplementation on body composition and performance in male athletes: A double-blinded randomized clinical trial 

This double-blinded, randomized and placebo-controlled clinical trial aimed to investigate the effect of L-arginine supplementation on sports performance and body composition in male soccer players. Participants were randomized to receive either a placebo or L-arginine (2 g per day) for 45 days. The results showed an improvement in sports performance, as observed by VO2 max results, in the arginine supplemented group; although no significant effect was observed on weight, BMI, BFM and LBM. 

References:

Pahlavani, N., Entezari, M. H., Nasiri, M., Miri, A., Rezaie, M., Bagheri-Bidakhavidi, M., & Sadeghi, O. (2017). The effect of l-arginine supplementation on body composition and performance in male athletes: a double-blinded randomized clinical trial. European journal of clinical nutrition, 71(4), 544–548. https://doi.org/10.1038/ejcn.2016.266