کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5514180 | 1541590 | 2017 | 8 صفحه PDF | دانلود رایگان |
- 13Â mmol NO3â significantly elevated plasma NO3â and NO2â levels in trained athletes.
- However, there was no benefit of acute NO3â supplementation in normoxia or hypoxia.
- Physiological responses to submaximal exercise were not altered by NO3â ingestion.
- Neither was roller-skiing time-trial performance improved with NO3â supplementation.
The present study examined the effects of acute nitrate (NO3â) 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, V·O2max 71.5 ± 4.7 mL kgâ1·minâ1; three females: age 21 ± 1 years, V·O2max 58.4 ± 2.5 mL kgâ1·minâ1) were supplemented with a single dose of NO3â-rich beetroot juice (BRJ, â¼13 mmol NO3â) or a NO3â-depleted placebo (PL, â¼0 mmol NO3â) 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 NO3â 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 â¼13 mmol NO3â does not affect physiological or performance responses to submaximal or maximal treadmill roller-skiing in competitive cross-country skiers exercising in N and H.
Journal: Nitric Oxide - Volume 70, 1 November 2017, Pages 1-8