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

The aim of this study was to investigate the later effects of daily NO3- supplementation over 3 wk of training on the relationship between O-2 uptake and power at different intensities with an incremental test (IT), a double-wingate test (WT), and an endurance capacity test at 80% W-max(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 W-max - 10 W and an active recovery period of 10 W in between with dietary NO3- (NaNO3) or placebo supplementation (NaCl) (both 8.5 mg.kg(-1).day(-1)) on a cycle ergometer. During a training session, plasma [NO3-] (P < 0.001) and plasma [NO2-] (P < 0.01) were higher in nitrate (N), whereas in pre- and posttests mean plasma [NO3-] and [NO] were not different between groups. In the WT [48 h after cessation of supplementation (C)]. the ratio between <(V)over dot>o(2) 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 <(V)over dot>o(2).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 <(V)over dot>o(2) 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 NO3- supplementation on exercise performance during a supplementation period, the sustainability of the effects of the NO(3)(-)supplementation remain unknown. We followed the development of <(V)over dot>o(2)/W at different intensities during the first week after cessation of daily NO3- supplementation over 3 wk. The results indicate that NO3- supplementation has a long-term effect for at least 7 days after cessation during heavy all-out workloads without affecting endurance capacity.