Physiological Reports · May 2023

The influence of acute dietary nitrate supplementation on skeletal muscle fatigue and recovery in older women

By Zoughaib WS, Hoffman RL, Yates BA et al.

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 the NO₃ ⁻ → 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 years) women who were administered an acute dose of beetroot juice (BRJ) containing either 15.6 ± 3.6 or <0.05 mmol of NO₃ ⁻ . 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 at 3.14 rad/s 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.

doi.org/10.14814/phy2.15694Open accessPubMed 37226336Interventions