In a recently study which included just 9 recreationally active males, researchers studied the effect of acute ingestion of l-arginine supplementation on high-intensity exercise tolerance (Bailey et al, 2010). L-arginine is an amino acid.
The subjects who were between the ages of 19-38 years of age consumed a beverage either consisting of 6g of l-arginine or placebo 1 hour prior to completely moderate to high-intensity exercise bouts on a cycling erogmeter.
“Participants received a 20 g dose of the 163 ARK 1 supplement which contained 6 g L-arginine along with trace amounts of vitamins (E, C, B6 and B12), other amino acids (L-glutamine, L-leucine, L-valine, L-carnitine, L-citrulline, L-cysteine and L-isoleucine), and fructose (11 g) at a dose that would not be expected to elicit performance gains.”
- Plasma nitrate was significantly higher following l-arginine supplementation compared to placebo (ARG: 331 +/- 198 vs. PLA: 159 +/- 102 nM; P<0.05)
- Systolic blood pressure was significantly lower following l-arginine supplementation compared to placebo (ARG: 123 +/- 3 vs. PLA: 131 +/- 5 mmHg; P<0.01)
- Steady-state VO(2) during moderate-intensity exercise was reduced by 7% in the l-arginine group (ARG: 1.48 +/- 0.12 vs. PLA: 1.59 +/- 0.14 L*min(-1); P<0.05).
“During severe-intensity exercise, the VO(2) slow component amplitude was reduced (ARG: 0.58 +/- 0.23 vs. PLA: 0.76 +/- 0.29 L*min(-1); P<0.05) and the time-to-exhaustion was extended (ARG: 707 +/- 232 s vs. PLA: 562 +/- 145 s; P<0.05) following ARG.”
Study Author Conclusions:
“Acute dietary supplementation with 6 g L-arginine, which increased indices of NO synthesis, reduced the steady-state O2 during moderate-intensity exercise, and also reduced the O2 slow component and increased the time to task failure during severe intensity exercise in healthy adults.”
What Does This Mean?
From the researchers:
“During moderate intensity exercise, pulmonary oxygen update V0(2) increases exponentially until it reaches a steady state after two to three minutes. Steady-state VO(2) or pulmonary oxygen update reflects the rate of ATP turnover in the myocytes (muscle cells) which is directly related to the external work load (exercise intensity).”
During high-intensity exercise, muscle contractility progressively declines during which a V0(2) slow component is apparent. The V0(2) slow component delays the attainment of a steady-state and sets the V0(2) on a trajectory towards its maximum [V0(2) peak]. Interventions which reduce the amplitude of the V0(2) slow component reportedly improve severe-intensity exercise tolerance.
In short, this recent study suggests that a diet rich in l-arginine improves exercise efficiency and exercise tolerance in healthy males.
- Bailey SJ, Winyard PG, Vanhatalo A, Blackwell JR, Dimenna FJ, Wilkerson DP, Jones AM. Acute L-arginine supplementation reduces the O2 cost of moderate-intensity exercise and enhances high-intensity exercise tolerance. J Appl Physiol. 2010 Aug 19.