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The present study examined the effects of acute nitrate (NO3-) supplementation ingested in the form of concentrated beetroot juice on cross-country roller-ski performance in normoxia (N) and normobaric hypoxia (H). Eight competitive cross-country skiers (five males: age 22 ± 3 years, V̇O2max 71.5 ± 4.7 mL·kg-1·min-1; three females: age 21 ± 1 years, V̇O2max 58.4 ± 2.5 mL·kg-1·min-1) were supplemented with a single dose of NO3--rich beetroot juice (BRJ, ~ 13 mmol NO3-) or a NO3--depleted placebo (PL, ~ 0 mmol NO3-) and performed 2 x 6-min submaximal exercise bouts and a 1000-m time-trial (TT) on a treadmill in N (20.9% O2) or H (16.8% O2). The four experimental trials were presented in a randomised, counter-balanced order. Plasma NO3- and nitrite concentrations were significantly higher following BRJ compared to PL (both p < 0.001). However, respiratory variables, heart rate, blood lactate concentration, ratings of perceived exertion, and near-infrared spectroscopy-derived measures of muscle tissue oxygenation during submaximal exercise were not significantly different between BRJ and PL (all p > 0.05). Likewise, time to complete the TT was unaffected by supplementation in both N and H (p > 0.05). In conclusion, an acute dose of ~ 13 mmol NO3- does not affect physiological or performance responses to submaximal or maximal treadmill roller-skiing in competitive cross-country skiers exercising in N and H. The present study examined the effects of acute nitrate (NO3-) supplementation ingested in the form of concentrated beetroot juice on cross-country roller-ski performance in normoxia (N) and normobaric hypoxia (H). Eight competitive cross-country skiers (five males: age 22 ± 3 years, V̇O2max 71.5 ± 4.7 mL·kg-1·min-1; three females: age 21 ± 1 years, V̇O2max 58.4 ± 2.5 mL·kg-1·min-1) were supplemented with a single dose of NO3--rich beetroot juice (BRJ, ~ 13 mmol NO3-) or a NO3--depleted placebo (PL, ~ 0 mmol NO3-) and performed 2 x 6-min submaximal exercise bouts and a 1000-m time-trial (TT) on a treadmill in N (20.9% O2) or H (16.8% O2). The four experimental trials were presented in a randomised, counter-balanced order. Plasma NO3- and nitrite concentrations were significantly higher following BRJ compared to PL (both p < 0.001). However, respiratory variables, heart rate, blood lactate concentration, ratings of perceived exertion, and near-infrared spectroscopy-derived measures of muscle tissue oxygenation during submaximal exercise were not significantly different between BRJ and PL (all p > 0.05). Likewise, time to complete the TT was unaffected by supplementation in both N and H (p > 0.05). In conclusion, an acute dose of ~ 13 mmol NO3- does not affect physiological or performance responses to submaximal or maximal treadmill roller-skiing in competitive cross-country skiers exercising in N and H.
Author(s): Nybäck L, Glannerud C, Larsson G, Weitzberg E, Shannon OM, McGawley K
Publication type: Article
Publication status: Published
Journal: Nitric Oxide
Year: 2017
Volume: 70
Pages: 1-8
Print publication date: 01/11/2017
Online publication date: 04/08/2017
Acceptance date: 02/08/2017
ISSN (print): 1351-525X
Publisher: Elsevier
URL: https://doi.org/10.1016/j.niox.2017.08.001
DOI: 10.1016/j.niox.2017.08.001
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