Composition improves performance and use thereof

A method for non-therapeutic performance improvement of a mammal, said performance improvement manifested as a lower oxygen consumption (VO2) during exercise, characterized in that inorganic nitrate, inorganic nitrite or a combination thereof is administered orally, in the dose of nitrate is 0.01 to 10 mmol of sodium nitrate / kg body weight / day, the dose of nitrite is 0.001 to 1 mmol / kg body weight / day, and wherein the range of the ratio of dose when the nitrate and nitrite are administered in combination is 5: 1 to 100: 1 (nitrate: nitrite), wherein said performance is improved compared to the physical performance of the said mammal during exercise, in the absence of said administration of nitrate and / or inorganic nitrite.