Effects of dietary nitrate, caffeine, and their combination on 20-km cycling time trial performance
| Autor: | John R. Pattison, Paul Foley, Daniel Muniz-Pumares, Stephen D. Patterson, Mark Glaister |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Adult
medicine.medical_specialty Physical Exertion Physical Therapy Sports Therapy and Rehabilitation Beetroot Juice Athletic Performance Placebo law.invention chemistry.chemical_compound Time trial Animal science Oxygen Consumption Randomized controlled trial Nitrate Double-Blind Method law Heart Rate Caffeine Heart rate Medicine Humans Orthopedics and Sports Medicine Nitrates business.industry General Medicine Bicycling chemistry Dietary Supplements Physical therapy Physical Endurance Female business Cycling |
| Zdroj: | Scopus-Elsevier |
| ISSN: | 1533-4287 1064-8011 |
| Popis: | The aim of this study was to examine the acute supplementation effects of dietary nitrate, caffeine, and their combination on 20-km cycling time trial performance. Using a randomized, counterbalanced, double-blind Latin-square design, 14 competitive female cyclists (age: 31 ± 7 years; height: 1.69 ± 0.07 m; body mass: 61.6 ± 6.0 kg) completed four 20-km time trials on a racing bicycle fitted to a turbo trainer. Approximately 2.5 hours before each trial, subjects consumed a 70-ml dose of concentrated beetroot juice containing either 0.45 g of dietary nitrate or with the nitrate content removed (placebo). One hour before each trial, subjects consumed a capsule containing either 5 mg·kg of caffeine or maltodextrin (placebo). There was a significant effect of supplementation on power output (p = 0.001), with post hoc tests revealing higher power outputs in caffeine (205 ± 21 W) vs. nitrate (194 ± 22 W) and placebo (194 ± 25 W) trials only. Caffeine-induced improvements in power output corresponded with significantly higher measures of heart rate (caffeine: 166 ± 12 b·min vs. placebo: 159 ± 15 b·min; p = 0.02), blood lactate (caffeine: 6.54 ± 2.40 mmol·L vs. placebo: 4.50 ± 2.11 mmol·L; p0.001), and respiratory exchange ratio (caffeine: 0.95 ± 0.04 vs. placebo: 0.91 ± 0.05; p = 0.03). There were no effects (p ≥ 0.05) of supplementation on cycling cadence, rating of perceived exertion, (Equation is included in full-text article.), or integrated electromyographic activity. The results of this study support the well-established beneficial effects of caffeine supplementation on endurance performance. In contrast, acute supplementation with dietary nitrate seems to have no effect on endurance performance and adds nothing to the benefits afforded by caffeine supplementation. |
| Databáze: | OpenAIRE |
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