Influence of Dietary Nitrate Supplementation on High-Intensity Intermittent Running Performance at Different Doses of Normobaric Hypoxia in Endurance-Trained Males.

Abstract

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.

• Authors: George P Robinson, Sophie C Killer, Zdravko Stoyanov, Harri Stephens, Luke Read, Lewis J James, Stephen J Bailey
• Journal: International journal of sport nutrition and exercise metabolism (Int J Sport Nutr Exerc Metab) Vol. 31 Issue 1 Pg. 1-8 (01 01 2021) ISSN: 1543-2742 [Electronic] United States
• PMID: 33260146 (Publication Type: Journal Article)

Chemical References

• Nitrates
• Performance-Enhancing Substances
• Oxygen

Topics

• Adult
• Altitude
• Beta vulgaris (chemistry)
• Dietary Supplements
• Endurance Training
• Exercise Test
• Fruit and Vegetable Juices
• Humans
• Hypoxia (physiopathology)
• Male
• Nitrates (administration & dosage, blood)
• Oxygen (blood)
• Performance-Enhancing Substances (administration & dosage)
• Physical Endurance (drug effects)
• Running (physiology)
• Young Adult