Bailey, S. J., Vanhatalo, A., Winyard, P. G., & Jones, A. M. (2012). Mechanistic bases for effects of nitrate supplementation on metabolism. Presentation 23 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.

This study investigated the mechanistic bases for the improved exercise efficiency observed after dietary nitrate (NO3-) supplementation in younger (N = 8; 19-45 yrs) and older (N = 12: 60-70 yrs) adults. Ss consumed 2 x 70 mL per day of either a concentrated nitrate-rich beetroot juice (~0.3 g nitrate) or a nitrate-depleted beetroot juice placebo (~0.00074 mg nitrate) for three consecutive days. On the third day of each dietary intervention period, Ss completed two 24-second bouts of high-intensity single-legged knee-extensor exercise in the supine body position within the bore of a 1.5-T superconducting magnet. Muscle oxidative function was estimated in vivo from the post-exercise recovery time constant of intramuscular phosphocreatine (PCr).

The PCr recovery time constants were not different after nitrate-rich beetroot juice supplementation compared to nitrate-depleted beetroot juice supplementation in either younger or older adults. Nitrate supplementation did not affect muscle oxidative function.

Implication. The mechanistic bases for the improved exercise efficiency after dietary nitrate supplementation are not related to muscle oxidative function and do not change with aging.

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