No effect of acute l-arginine supplementation on O sub(2) cost or exercise tolerance

• Published in: European journal of applied physiology Vol. 113; no. 7; pp. 1805 - 1819
• Main Authors: Vanhatalo, Anni, Bailey, Stephen J, DiMenna, Fred J, Blackwell, Jamie R, Wallis, Gareth A, Jones, Andrew M
• Format: Journal Article
• Language: English
• Published: 01.07.2013
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-013-2593-z

The extent to which dietary supplementation with the nitric oxide synthase (NOS) substrate, l-arginine (ARG), impacts on NO production and NO-mediated physiological responses is controversial. This randomised, double blinded, cross-over study investigated the effects of acute ARG supplementation on NO biomarkers, O sub(2) cost of exercise and exercise tolerance in humans. In one experiment, 15 subjects completed moderate- and severe-intensity running bouts after acute supplementation with 6 g ARG or placebo (PLA). In another experiment, eight subjects completed moderate- and severe-intensity cycling bouts after acute supplementation with 6 g ARG plus 25 g of carbohydrate (ARG + CHO) or an energy-matched dose of carbohydrate alone (CHO). The plasma nitrite concentration was not different after ARG (Pre: 204 plus or minus 79; Post: 241 plus or minus 114 nM; P > 0.05) or ARG + CHO consumption (Pre: 304 plus or minus 57; Post: 335 plus or minus 116 nM; P > 0.05). During moderate-intensity exercise, the steady-state pulmonary $$ \dot{V}{\text{O}}_{2} $$ was not different, relative to the respective placebo conditions, after ARG (PLA: 2,407 plus or minus 318, ARG: 2,422 plus or minus 333 mL min super(-1)) or ARG + CHO (CHO: 1,695 plus or minus 304, ARG + CHO: 1,712 plus or minus 312 mL min super(-1)) ingestion (P > 0.05). The tolerable duration of severe exercise was also not significantly different (P > 0.05) after ingesting ARG (PLA: 551 plus or minus 140, ARG: 552 plus or minus 150 s) or ARG + CHO (CHO: 457 plus or minus 182, ARG + CHO: 441 plus or minus 221 s). In conclusion, acute dietary supplementation with ARG or ARG + CHO did not alter biomarkers of NO synthesis, O sub(2) cost of exercise or exercise tolerance in healthy subjects.