Beetroot juice supplementation does not improve performance of elite 1500-m runners.

Abstract

Dietary nitrate supplementation with beetroot juice (BR) has received widespread attention as an ergogenic aid. However, recent evidence in well-trained cyclists has not consistently reported improved cycling economy or performance. The present study examined the effects of acute and chronic BR supplementation on V˙O2 during submaximal running and 1500-m time trial (TT) performance of elite distance runners. Eight male 1500-m runners (V˙O2peak, 80 ± 5 mL·kg·min; 1500-m personal best, 3:56 ± 9 s) participated in this study. In a randomized, double-blind, crossover design, subjects supplemented with BR or a nitrate-free BR placebo (PL) for 8 d separated by at least 1 wk. On days 1 (acute) and 8 (chronic), subjects ingested 210 mL of BR (19.5-mmol nitrate) or PL and completed a submaximal treadmill run and 1500-m TT on an indoor 200-m track. Plasma nitrate increased from 37 ± 15 to 615 ± 151 μM (acute) and 870 ± 259 μM (chronic) after BR supplementation. There were no V˙O2 differences between conditions at 50%, 65%, and 80% V˙O2peak (acute PL, 4194 ± 90 mL·min; chronic PL, 4216 ± 95 mL·min; acute BR, 4192 ± 113 mL·min; chronic BR, 4299 ± 92 mL·min). The 1500-m TT was unaffected by acute or chronic BR supplementation (acute PL, 4:10.4 min:s ± 2.5 s; chronic PL, 4:11.4 min:s ± 2.7 s; acute BR, 4:10.7 min:s ± 1.5 s; chronic BR, 4:10.5 min:s ± 2.2 s). However, two subjects improved their TT performance after acute (5.8 and 5.0 s) and chronic BR supplementation (7.0 and 0.5 s). Acute and chronic BR supplementation did not reduce running V˙O2 or improve 1500-m TT performance of a group of elite distance runners, but two responders to BR were identified.