Long-term effects of NO3– on the relationship between oxygen uptake and power after three weeks of supplemented HIHVT

Abstract

The aim of this study was to investigate the later effects of daily [Formula: see text] supplementation over 3 wk of training on the relationship between O2 uptake and power at different intensities with an incremental test (IT), a double-wingate test (WT), and an endurance capacity test at 80% Wmax (ECT) before and after the supplementation period. Seventeen male recreational athletes participated in this double-blind placebo (PL)-controlled study. Subjects participated in a 3-wk intermittent high-intensity, high-volume training period with 45 intervals of Wmax − 10 W and an active recovery period of 10 W in between with dietary [Formula: see text] (NaNO3) or placebo supplementation (NaCl) (both 8.5 mg·kg−1·day−1) on a cycle ergometer. During a training session, plasma [[Formula: see text]] ( P < 0.001) and plasma [[Formula: see text]] ( P < 0.01) were higher in nitrate (N), whereas in pre- and posttests mean plasma [[Formula: see text]] and [[Formula: see text]] were not different between groups. In the WT [48 h after cessation of supplementation (C)], the ratio between V̇o2 and power decreased in N ( P < 0.01) with no changes in PL. Endurance capacity (4–5 days after C) similarly increased in both groups ( P < 0.01). However, the total oxygen consumption decreased by 5% ( P < 0.01) in N, with no change in PL. The slope of V̇o2·W−1 in IT (5–7 days after C) decreased in N ( P < 0.01), whereas no changes were found in PL. During low- and moderate-intensity workloads, no changes and differences in V̇o2 could be detected. We conclude that nitrate supplementation causes a sustaining reduction of the oxygen cost per watt during exercise with a large recruitment of type II muscle fibers without affecting endurance capacity. NEW & NOTEWORTHY Because most studies focused on the acute effects of [Formula: see text] supplementation on exercise performance during a supplementation period, the sustainability of the effects of the [Formula: see text] supplementation remain unknown. We followed the development of V̇o2/W at different intensities during the first week after cessation of daily [Formula: see text] supplementation over 3 wk. The results indicate that [Formula: see text] supplementation has a long-term effect for at least 7 days after cessation during heavy all-out workloads without affecting endurance capacity.