Acute Administration of Inorganic Nitrate Reduces (V) over dotO2peak in Endurance Athletes

BESCOS, R., F. A. RODRIGUEZ, X. IGLESIAS, M. D. FERRER, E. IBORRA, and A. PONS. Acute Administration of Inorganic Nitrate Reduces (V) over dotO(2peak) in Endurance Athletes. Med. Sci. Sports Exerc., Vol. 43, No. 10, pp. 1979-1986, 2011. Purpose: Humans can reduce inorganic nitrate (NO3-) to nitrite (NO2-), nitric oxide (NO), and other bioactive nitrogen oxides. The purpose of this study was to test the hypothesis that a single dose of inorganic nitrate before exercise might enhance the tolerance of endurance athletes to high intensity exercise. Methods: Eleven cyclists (age = 34.3 +/- 4.8 yr, (V) over dotO(2peak) = 65.1 +/- 6.2 mL.kg(-1).min(-1)) participated in this randomized, double-blind, crossover study. Subjects received dietary supplementation with nitrate (NaNO3 10 mg.kg(-1) of body mass) or a placebo (NaCl) 3 h before exercise. They then performed a cycle ergometer test that consisted of four 6-min submaximal workloads, corresponding to 2.0, 2.5, 3.0, and 3.5 W.kg(-1) of body mass, interspersed with 3 min of passive recovery. After a 5-min recovery period, subjects performed one incremental exercise test until exhaustion. Results: Plasma nitrate and nitrite were significantly higher (P < 0.05) 3 h after supplementation (nitrate = 250 +/- 80 mu M, nitrite = 2313 +/- 157 nM) than after the placebo (nitrate = 29 +/- 8 mu M, nitrite = 1998 +/- 206 nM) at resting conditions. Nitrate supplementation significantly reduced (V) over dotO(2peak) (nitrate = 4.64 +/- 0.35 L.min(-1), placebo = 4.82 +/- 0.33 L.min(-1), P = 0.010) and the ratio between (V) over dotO(2) and power at maximal intensity (nitrate = 11.2 +/- 1.1 mL.min(-1).W-1, placebo = 11.8 +/- 1.1 mL.min(-1).W-1, P = 0.031). This reduction of (V) over dotO(2) occurred without changes in the time to exhaustion (nitrate = 416 +/- 32 s, placebo = 409 +/- 27 s) or in the maximal power (nitrate = 416 +/- 29 W, placebo = 410 +/- 28 W). Conclusions: A single oral dose of inorganic nitrate acutely reduces (V) over dotO(2peak) without compromising the maximal exercise performance.