Dietary nitrate supplementation does not improve cycling time-trial performance in the heat

• Published in: Journal of sports sciences 2018-06, Vol.36 (11), p.1204-1211
• Main Authors: Kent, Georgina L., Dawson, Brian, Cox, Gregory R., Burke, Louise M., Eastwood, Annette, Croft, Kevin D., Peeling, Peter
• Format: Article
• Language: English
• Subjects: Adult; Athletic Performance - physiology; Beetroot juice; Bicycling; Bicycling - physiology; Body Temperature Regulation - physiology; Dietary Supplements; Double-Blind Method; endurance; Exercise Test; Fruit and Vegetable Juices; Heart Rate - physiology; Heat; Hot Temperature; Humans; Male; Nitrates; Nitrates - administration & dosage; Nitrates - metabolism; Nitrites - metabolism; Perception - physiology; Physical Exertion - physiology; Relative humidity; Saliva - metabolism; Skin; Skin Temperature - physiology; Thermoregulation
• ISSN: 0264-0414; 1466-447X
• DOI: 10.1080/02640414.2017.1364404

This investigation examined the effect of beetroot juice (BR) supplementation, a source of dietary nitrate (NO 3 − ), on cycling time-trial (TT) performance and thermoregulation in the heat. In a double-blind, repeated-measures design, 12 male cyclists (age 26.6 ± 4.4 years, VO 2peak 65.8 ± 5.5 mL.kg −1 .min −1 ) completed four cycling TTs (14 kJ.kg −1 ) in hot (35°C, 48% relative humidity) and euthermic (21°C, 52%) conditions, following 3 days supplementation with BR (6.5 mmol NO 3 − for 2 days and 13 mmol NO 3 − on the final day), or NO 3 - depleted placebo (PLA). Salivary NO 3 − and nitrite, core (T c ) and mean skin temperature (T sk ) were measured. Salivary NO 3 − and nitrite increased significantly post-BR supplementation (p