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Influence of dietary nitrate supplementation on high-intensity intermittent running performance at different doses of normobaric hypoxia in endurance-trained males

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posted on 04.12.2020, 15:13 by George RobinsonGeorge Robinson, Sophie Killer, Zdravko Stoyanov, Harri Stephens, Luke Read, Lewis JamesLewis James, Stephen BaileyStephen Bailey
This study investigated whether supplementation with nitrate-rich beetroot juice (BR) can improve high-intensity intermittent running performance in trained males in normoxia and different doses of normobaric hypoxia. Eight endurance-trained males (V˙O2peak, 62 ± 6 ml·kg−1·min−1) completed repeated 90 s intervals at 110% of peak treadmill velocity, from an initial step incremental test, interspersed by 60 s of passive recovery until exhaustion (Tlim). Participants completed the first three experimental trials during days 3, 5, and 7 of BR or nitrate-depleted beetroot juice (PLA) supplementation and completed the remaining experimental visits on the alternative supplement following at least 7 days of washout. The fraction of inspired oxygen during visits 1–3 was either 0.209, 0.182, or 0.157, equivalent to an altitude of 0, 1,200, and 2,400 m, respectively, and this order was replicated on visits 4–6. Arterial oxygen saturation declined dose dependently as fraction of inspired oxygen was lowered (p < .05). Plasma nitrite concentration was higher pre- and postexercise after BR compared with PLA supplementation (p < .05). There was no difference in Tlim between PLA and BR at 0 m (445 [324, 508] and 410 [368, 548] s); 1,200 m (341 [270, 390] and 332 [314, 356] s); or 2,400 m (233 [177, 373] and 251 [221, 323] s) (median and [interquartile range]; p > .05). The findings from this study suggest that short-term BR supplementation does not improve high-intensity intermittent running performance in endurance-trained males in normoxia or at doses of normobaric hypoxia that correspond to altitudes at which athletes typically train while on altitude training camps.

Funding

UK Athletics and English Institute of Sport

History

School

  • Sport, Exercise and Health Sciences

Published in

International Journal of Sport Nutrition and Exercise Metabolism

Volume

31

Issue

1

Pages

1-8

Publisher

Human Kinetics

Version

AM (Accepted Manuscript)

Rights holder

© Human Kinetics, Inc.

Publisher statement

Accepted author manuscript version reprinted, by permission, from International Journal of Sport Nutrition and Exercise Metabolism, 2020, https://doi.org/10.1123/ijsnem.2020-0198. © Human Kinetics, Inc.

Acceptance date

29/09/2020

Publication date

2021-01-31

Copyright date

2021

ISSN

1526-484X

eISSN

1543-2742

Language

en

Depositor

Dr Stephen Bailey. Deposit date: 29 September 2020