The effects of dietary nitrate ingestion on physical performance tests in 50-65 years old postmenopausal women: A pilot randomized, double-blind, placebo-controlled, and crossover study

Background & Aims The post-menopausal period represents a noteworthy stage in a woman's life characterized by hormonal shifts that can influence diverse biological processes encompassing energy metabolism and physical performance. NO3- effects on physical performance in 50-65 years old postmenopausal women after short-term supplementation remain unknown. Methods This is a randomized, double-blind, placebo-controlled, crossover study. After two sessions in non-consecutive days of familiarization tests, fifteen post-menopausal women aged between 50 and 65 were enrolled in this study. The trial consisted of two eight-day arms: a) NO3- -70 mL of beetroot juice (BRJ) with ˜400 mg of NO3-, and b) placebo (PLA) –70 mL of BRJ NO3- depleted. Both interventions were obtained from the same manufacturer’s product, presenting the same organoleptic properties. After this period, five physical performance tests (handgrip strength, arm curl, sit-to-stand, agility and dynamic balance and 6-minute walk test (6MWT)) were applied. Results Fourteen participants completed all experimental protocols, including a minimum seven-day washout period between protocols. NO2− plasma concentrations were consistently elevated in the NO3- condition at 0.41(0.40) μM compared to the PLA at 0.18(0.18) μM (p<0.001). The 6MWT showed higher values in BRJ with NO3- condition (19.60 meters [95%CI: 1.33 to 37.88]; p=0.038), while the other physical performance tests did not show significant difference between conditions (p>0.05). Conclusions Our findings suggest benefits in the physical performance of activities with longer durations, indicating that the adaptation caused by ingestion of NO3- may be related to the cardiorespiratory capacity.