title: Acute Beetroot Juice Supplementation Does Not Improve Cycling Performance in Normoxia or Moderate Hypoxia.
abstract: Beetroot juice (BR) has been shown to lower the oxygen cost of exercise in normoxia and may have similar effects in hypoxia. We investigated the effect of BR on steady-state exercise economy and 10-km time trial (TT) performance in normoxia and moderate hypoxia (simulated altitude: ~2500 m). Eleven trained male cyclists (VO 2peak ≥ 60 ml · kg(-1) · min(-1)) completed four exercise trials. Two hours before exercise, subjects consumed 70 mL BR (~6 mmol nitrate) or placebo (nitrate-depleted BR) in a randomized, double-blind manner. Subjects then completed a 15-min self-selected cycling warm-up, a 15-min steady-state exercise bout at 50% maximum power output, and a 10-km time trial (TT) in either normoxia or hypoxia. Environmental conditions were randomized and single-blind. BR supplementation increased plasma nitrate concentration and fraction of exhaled nitric oxide relative to PL (p < .05 for both comparisons). Economy at 50% power output was similar in hypoxic and normoxic conditions (p > .05), but mean power output was greater in the normoxic TT relative to the hypoxic TT (p < .05). BR did not affect economy, steady-state SpO2, mean power output, or 10-km TT completion time relative to placebo in either normoxia or hypoxia (p > .05 in all comparisons). In conclusion, BR did not lower the oxygen cost of steady-state exercise or improve exercise performance in normoxia or hypoxia in a small sample of well-trained male cyclists.
authors: School of Kinesiology, University of British Columbia, Vancouver, Canada.
authors: Kristin E
authors: KE
authors: MacLeod
authors: Sean F
authors: SF
authors: Nugent
authors: Susan I
authors: SI
authors: Barr
authors: Michael S
authors: MS
authors: Koehle
authors: Benjamin C
authors: BC
authors: Sporer
authors: Martin J
authors: MJ
authors: MacInnis
mesh_terms: D000328:Adult; D054874:Athletic Performance; D027461:Beta vulgaris / Q000737:chemistry*; D001642:Bicycling; D001944:Breath Tests; D001955:British Columbia; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005221:Fatigue / Q000097:blood / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control*; D000067030:Fruit and Vegetable Juices / Q000032:analysis; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D008297:Male; D009566:Nitrates / Q000097:blood / Q000378:metabolism / Q000627:therapeutic use; D009569:Nitric Oxide / Q000032:analysis / Q000378:metabolism; D010101:Oxygen Consumption; D058573:Performance-Enhancing Substances / Q000627:therapeutic use; D018517:Plant Roots / Q000737:chemistry*; D012720:Severity of Illness Index; D016037:Single-Blind Method; D064133:Sports Nutritional Physiological Phenomena
chemical_list: D009566:Nitrates; D058573:Performance-Enhancing Substances; D009569:Nitric Oxide