Older individuals fatigue more rapidly during, and recover more slowly from, dynamic exercise. Women are particularly vulnerable to these deleterious effects of aging, which increases their risk of falling. We have shown that dietary nitrate (NO3-), a source of nitric oxide (NO) via theNO3- → nitrite (NO2-) → NO pathway, enhances muscle speed and power in older individuals in the non-fatigued state; however, it is unclear if it reduces fatigability and/or improves recoverability in this population. Using a double-blind, placebo-controlled, crossover design, we studied 18 older (age 70±4 y) women who were administered an acute dose of beetroot juice (BRJ) either containing NO3- (15.6±3.6 mmol) or devoid of NO3- (placebo). Blood samples were drawn throughout each ~3 h visit for plasma NO3- and NO2- analysis. Peak torque was measured during, and periodically for 10 min after, 50 maximal knee extensions performed on an isokinetic dynamometer. Ingestion of NO3--containing BRJ increased plasma NO3- and NO2- concentrations by 21±8 and 4±4 fold, respectively. However, there were no differences in muscle fatigue or recovery. Dietary NO3- increases plasma NO3- and NO2- concentrations but does not reduce fatigability during or enhance recoverability after high intensity exercise in older women.

The authors have declared no competing interest.

NCT03595774

This work was supported by the Office of the Vice Provost for Research at Indiana University Purdue University Indianapolis and by the National Institutes of Health (grant numbers R21 AG053606 to ARC, K23 DK102824 to RNM, P30 AR072581 to Sharon Moe, and UL1 TR002529 to Anantha Shekhar). The contents of this article are solely the responsibility of the authors and do not necessarily represent the official view of the National Institutes of Health.

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