Beetroot juice does not enhance altitude running performance in well-trained athletes.
We hypothesized that acute dietary nitrate (NO3(-)) provided as concentrated beetroot juice supplement would improve endurance running performance of well-trained runners in normobaric hypoxia. Ten male runners (mean (SD): sea level maximal oxygen uptake, 66 (7) mL·kg(-1)·min(-1); 10 km personal best, 36 (2) min) completed incremental exercise to exhaustion at 4000 m and a 10-km treadmill time-trial at 2500 m simulated altitude on separate days after supplementation with ∼7 mmol NO3(-) and a placebo at 2.5 h before exercise. Oxygen cost, arterial oxygen saturation, heart rate, and ratings of perceived exertion (RPE) were determined during the incremental exercise test. Differences between treatments were determined using means [95% confidence intervals], paired sample t tests, and a probability of individual response analysis. NO3(-) supplementation increased plasma nitrite concentration (NO3(-), 473 (226) nmol·L(-1) vs. placebo, 61 (37) nmol·L(-1), P < 0.001) but did not alter time to exhaustion during the incremental test (NO3(-), 402 (80) s vs. placebo 393 (62) s, P = 0.5) or time to complete the 10-km time-trial (NO3(-), 2862 (233) s vs. placebo, 2874 (265) s, P = 0.6). Further, no practically meaningful beneficial effect on time-trial performance was observed as the 11 [-60 to 38] s improvement was less than the a priori determined minimum important difference (51 s), and only 3 runners experienced a "likely, probable" performance improvement. NO3(-) also did not alter oxygen cost, arterial oxygen saturation, heart rate, or RPE. Acute dietary NO3(-) supplementation did not consistently enhance running performance of well-trained athletes in normobaric hypoxia.
School of Sport, Health and Exercise Sciences, Bangor University, George Building, Bangor, Gwynedd LL57 2PZ., Centre for Health, Exercise and Sport Science, Southampton Solent University, Southampton SO17 1BJ, UK.
Josh Timothy
JT
Arnold
Samuel James
SJ
Oliver
Tammy Maria
TM
Lewis-Jones
Lee John
LJ
Wylie
Jamie Hugo
JH
Macdonald
D000328:Adult; D000531:Altitude; D056352:Athletes; D027461:Beta vulgaris / Q000737:chemistry*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005080:Exercise Test; D000067030:Fruit and Vegetable Juices; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009566:Nitrates / Q000097:blood; D009573:Nitrites / Q000097:blood; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption; D018517:Plant Roots / Q000737:chemistry; D012420:Running; D064133:Sports Nutritional Physiological Phenomena
D009566:Nitrates; D009573:Nitrites; D010100:Oxygen
exercice physique; exercise; hypoxia; hypoxie; nitrate; nitric oxide; nitrite; oxyde nitrique