Effects of arginine-based supplements on the physical working capacity at the fatigue threshold

The purpose of the present study was to examine the effects of daily oral administration of arginine-based supplements for 4 weeks on the physical working capacity at the fatigue threshold (PWC_FT). The PWC_FT test is an electromyographic (EMG) procedure for estimating the highest power output that can be maintained without neuromuscular evidence of fatigue. The study used a double-blind, placebo-controlled design. Fifty college-aged men (mean age ± SD = 23.9 ± 3.0) were randomized into 1 of 3 groups: (a) placebo (n = 19); (b) 1.5 g arginine (n = 14); or (c) 3.0 g arginine (n = 17). The placebo was microcrystalline cellulose. The 1.5-g arginine group ingested 1.5 g of arginine and 300 mg of grape seed extract, whereas the 3.0 g arginine group ingested 3.0 g of arginine and 300 mg of grape seed extract. All subjects performed an incremental test to exhaustion on a cycle ergometer to determine their PWC_FT before supplementation (PRE) and after 4 weeks of supplementation (POST). Surface EMG signals were recorded from the vastus lateralis using a bipolar electrode arrangement during the incremental tests for the determination of the PRE and POST supplementation PWC_FT values. There were significant mean increases (PRE to POST) in PWC_FT for the 1.5 g (22.4%) and 3.0 g (18.8%) supplement groups, but no change for the placebo group (-1.6%). These findings supported the use of arginine-based supplements, at the dosages examined in the present investigation, as an ergogenic aid for untrained individuals.