Long-term effects of 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 $$ supplementation over 3 wk of training on the relationship between O₂ uptake and power at different intensities with an incremental test (IT), a double-wingate test (WT), and an endurance capacity test at 80% W_max (ECT) before and after the supplementation period. Seventeen male recreational athletes participated in this double-blind placebo (PL)-controlled study. Subjects participated in a 3-wk intermittent high-intensity, high-volume training period with 45 intervals of W_max - 10 W and an active recovery period of 10 W in between with dietary $$ (NaNO₃) or placebo supplementation (NaCl) (both 8.5 mg·kg^-1·day^-1) on a cycle ergometer. During a training session, plasma [ $$ ] ( P < 0.001) and plasma [ $$ ] ( P < 0.01) were higher in nitrate (N), whereas in pre- and posttests mean plasma [ $$ ] and [ $$ ] 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 $$ supplementation on exercise performance during a supplementation period, the sustainability of the effects of the $$ supplementation remain unknown. We followed the development of V̇o₂/W at different intensities during the first week after cessation of daily $$ supplementation over 3 wk. The results indicate that $$ supplementation has a long-term effect for at least 7 days after cessation during heavy all-out workloads without affecting endurance capacity.