Acute L-arginine supplementation reduced steady-state O2 uptake during moderate-intensity exercise (1.48 vs 1.59 l/min, P<0.05) and extended time to exhaustion during severe-intensity exercise.
RCT (n=9)
Double-blind
Does acute L-arginine supplementation reduce the O2 cost of moderate-intensity exercise and enhance high-intensity exercise tolerance in healthy men?
Acute L-arginine supplementation improves exercise efficiency and tolerance in healthy young men, likely by increasing nitric oxide bioavailability.
Absolute Event Rate: 1.48% vs 1.59%
p-value: p=< 0.05
It has recently been reported that dietary nitrate (NO(3)(-)) supplementation, which increases plasma nitrite (NO(2)(-)) concentration, a biomarker of nitric oxide (NO) availability, improves exercise efficiency and exercise tolerance in healthy humans. We hypothesized that dietary supplementation with L-arginine, the substrate for NO synthase (NOS), would elicit similar responses. In a double-blind, crossover study, nine healthy men (aged 19-38 yr) consumed 500 ml of a beverage containing 6 g of l-arginine (Arg) or a placebo beverage (PL) and completed a series of "step" moderate- and severe-intensity exercise bouts 1 h after ingestion of the beverage. Plasma NO(2)(-) concentration was significantly greater in the Arg than the PL group (331 ± 198 vs. 159 ± 102 nM, P < 0.05) and systolic blood pressure was significantly reduced (123 ± 3 vs. 131 ± 5 mmHg, P < 0.01). The steady-state O(2) uptake (VO(2)) during moderate-intensity exercise was reduced by 7% in the Arg group (1.48 ± 0.12 vs. 1.59 ± 0.14 l/min, P < 0.05). During severe-intensity exercise, the Vo(2) slow component amplitude was reduced (0.58 ± 0.23 and 0.76 ± 0.29 l/min in Arg and PL, respectively, P < 0.05) and the time to exhaustion was extended (707 ± 232 and 562 ± 145 s in Arg and PL, respectively, P < 0.05) following consumption of Arg. In conclusion, similar to the effects of increased dietary NO(3)(-) intake, elevating NO bioavailability through dietary L-Arg supplementation reduced the O(2) cost of moderate-intensity exercise and blunted the VO(2) slow component and extended the time to exhaustion during severe-intensity exercise.
Bailey et al. (Thu,) conducted a rct in Healthy (n=9). l-arginine vs. Placebo was evaluated on Steady-state O2 uptake (VO2) during moderate-intensity exercise (p=< 0.05). Acute L-arginine supplementation reduced steady-state O2 uptake during moderate-intensity exercise (1.48 vs 1.59 l/min, P<0.05) and extended time to exhaustion during severe-intensity exercise.