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

Georgina L. Kent, Brian Dawson, Gregory R. Cox, Louise M. Burke, Annette Eastwood, Kevin D. Croft, Peter Peeling

    Research output: Contribution to journalArticle

    6 Citations (Scopus)

    Abstract

    This investigation examined the effect of beetroot juice (BR) supplementation, a source of dietary nitrate (NO3 ), 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, VO2peak 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 NO3 for 2 days and 13 mmol NO3 on the final day), or NO3 depleted placebo (PLA). Salivary NO3 and nitrite, core (Tc) and mean skin temperature (Tsk) were measured. Salivary NO3 and nitrite increased significantly post-BR supplementation (p < 0.001). Average TT completion time (mm:ss) in hot conditions was 56:50 ± 05:08 with BR, compared with 58:30 ± 04:48 with PLA (p = 0.178). In euthermic conditions, average completion time was 53:09 ± 04:35 with BR, compared with 54:01 ± 04:05 with PLA (p = 0.380). The TT performance decreased (p < 0.001), and Tc (p < 0.001) and Tsk (p < 0.001) were higher in hot compared with euthermic conditions. In summary, BR supplementation has no significant effect on cycling TT performance in the heat.

    Original languageEnglish
    Pages (from-to)1204-1211
    Number of pages8
    JournalJournal of Sports Sciences
    Volume36
    Issue number11
    DOIs
    Publication statusPublished - 3 May 2018

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