Study of the effect of oral administration of L-arginine on muscular performance in healthy volunteers:: An isokinetic study

A decrease of the blood supply to the muscle can be significant to the development of muscular fatigue, an important factor of incapacity. In this study, the effect of L-arginine taken orally, on the physiologic process of the muscular fatigue in 12 healthy volunteers, was investigated through located exercise controlled by isokinetic dynamometer (Biodex Multi-Joint System 3 dynamometer). A protocol of the isokinetic concentric, continuous and reciprocal test was used for acquisition of the Work Fatigue Indexes and it was accomplished the bilateral evaluation of the knee extension and flexion of the volunteers to an angular speed of 180degrees /s. The study was divided into two phases of test, Phase 1 being the control. At Phase 2, 3 g of arginine was given orally to each volunteer, daily for 15 days. The reliability and the estimate of the error in our measurements were analyzed, respectively, by Intra-class Correlation Coefficient (ICC) and Percent Standard Error of Measurement (SEM %). Reliable isokinetic measurements were obtained in the knee extension movement (ICC > 0.80). Results demonstrated that for knee extension movement the mean values of Work Fatigue Indexes of Phases 1 and 2 are statistically different (p < 0.05). There was a significant decrease (mean 8.5%) in the Work Fatigue Indexes. Our results indicate an improvement in the muscular resistance capacity to fatigue following the treatment by oral administration of arginine.