Nitrates have long been decried as toxic and dangerous and I bet, before their latest appearance to the supplement market, none of you would even have remotely considered to consciously increase his/her dietary nitrate supply. Yet, recent scientific studies confirm that nitrate (in moderate doses) is not only safe, but also has, its effects on vasodilation aside, quantifiable effects on exercise performance.
A group of scientists from the UK tried to find out the underlying mechanisms of the ergodicity of supplemental nitrate (Baily. 2011). Following a six day supplementation period in the course of which seven males (aged 19-38 yr) consumed 500 mL per day of either nitrate-rich beetroot juice (~300mg nitrate content) or placebo (PL, with negligible nitrate content). What they observed is best described as a "tuning effect" that was observable both, in the course of high, as well as in the course of low intensity exercise training.
During low intensity exercise, the pulmonary VO2 amplitude and thus the oxygen need during this kind of aerobic exercise decreased by -7%. An even more profound effect of nitrate supplementation was observed during high intensity activity (knee extensor exercises) where the ATP turnover decreased by -25%. These results stand in line with an overall increase in exercise tolerance of +25% in the nitrate supplemented group over placebo.
Other than a some other researchers had speculated, Baily et al. did not find any indications of a changed phosphate vs. oxygen (P/O) ratio in the muscle. The changes in ATP turnover a 6-day loading phase with dietary nitrate from beet root juice triggers, must thus be considered the underlying mechanism of the ergogenic effect of nitrates, which, as you may have notices, appear in various forms (amino acid nitrates, creatine nitrates, etc.) in recently released supplements - not without reason, as it turns out.