ABSTRACTOBJECTIVETo evaluate whether nitric oxide (NO) supplementa-tion is directly related to increased muscle power in response to strength exercise trainingMETHODSThe study included 36 individuals who underwent training for eight weeks (three times per week) with weights, who were randomly divided into two groups, both receiving the same training protocol, but one group used 3g of arginine, as a precursor of NO, and the other received placeboRESULTSThere was no significant difference between groups, only a significant difference for both groups between moments: before and after the training protocolCONCLUSIONOral administration of arginine asso-ciated with a training program did not increase the muscular power of individuals. Level of Evidence I, Study Type: Highquality randomized trial with statistically significant diffe-rence or no statistically significant difference but narrow confidence intervals.