title: Nitrate supplementation's improvement of 10-km time-trial performance in trained cyclists.
abstract: Six days of dietary nitrate supplementation in the form of beetroot juice (~0.5 L/d) has been reported to reduce pulmonary oxygen uptake (VO₂) during submaximal exercise and increase tolerance of high-intensity work rates, suggesting that nitrate can be a potent ergogenic aid. Limited data are available regarding the effect of nitrate ingestion on athletic performance, and no study has investigated the potential ergogenic effects of a small-volume, concentrated dose of beetroot juice. The authors tested the hypothesis that 6 d of nitrate ingestion would improve time-trial performance in trained cyclists. Using a double-blind, repeated-measures crossover design, 12 male cyclists (31±3 yr, VO2peak=58±2 ml·kg⁻¹·min⁻¹, maximal power [Wmax]=342±10 W) ingested 140 ml/d of concentrated beetroot (~8 mmol/d nitrate) juice (BEET) or a placebo (nitrate-depleted beetroot juice; PLAC) for 6 d, separated by a 14-d washout. After supplementation on Day 6, subjects performed 60 min of submaximal cycling (2×30 min at 45% and 65% Wmax, respectively), followed by a 10-km time trial. Time-trial performance (953±18 vs. 965±18 s, p<.005) and power output (294±12 vs. 288±12 W, p<.05) improved after BEET compared with PLAC supplementation. Submaximal VO₂ was lower after BEET (45% Wmax=1.92±0.06 vs. 2.02±0.09 L/min, 65% Wmax 2.94±0.12 vs. 3.11±0.12 L/min) than with PLAC (main effect, p<.05). Whole-body fuel selection and plasma lactate, glucose, and insulin concentrations did not differ between treatments. Six days of nitrate supplementation reduced VO₂ during submaximal exercise and improved time-trial performance in trained cyclists.
authors.affiliation: Department of Human Movement Sciences, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Naomi M
authors.initials: NM
authors.lastname: Cermak
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Gibala
authors.forename: Luc J C
authors.initials: LJ
authors.lastname: van Loon
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D027461:Beta vulgaris / Q000737:chemistry; D001628:Beverages / Q000009:adverse effects / Q000032:analysis; D001642:Bicycling; D001786:Blood Glucose / Q000032:analysis; D018592:Cross-Over Studies; D019587:Dietary Supplements / Q000009:adverse effects; D004311:Double-Blind Method; D002149:Energy Intake; D006801:Humans; D007328:Insulin / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D008297:Male; D009566:Nitrates / Q000008:administration & dosage* / Q000009:adverse effects; D010101:Oxygen Consumption; D058573:Performance-Enhancing Substances / Q000008:administration & dosage* / Q000009:adverse effects; D010807:Physical Endurance / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D018517:Plant Roots / Q000737:chemistry
chemical_list: D001786:Blood Glucose; D007328:Insulin; D009566:Nitrates; D058573:Performance-Enhancing Substances; D019344:Lactic Acid; C031618:sodium nitrate