title: Influence of dietary nitrate supplementation on physiological and muscle metabolic adaptations to sprint interval training.
abstract: We hypothesized that 4 wk of dietary nitrate supplementation would enhance exercise performance and muscle metabolic adaptations to sprint interval training (SIT). Thirty-six recreationally active subjects, matched on key variables at baseline, completed a series of exercise tests before and following a 4-wk period in which they were allocated to one of the following groups:1) SIT and [Formula: see text]-depleted beetroot juice as a placebo (SIT+PL);2) SIT and [Formula: see text]-rich beetroot juice (~13 mmol [Formula: see text]/day; SIT+BR); or3) no training and [Formula: see text]-rich beetroot juice (NT+BR). During moderate-intensity exercise, pulmonary oxygen uptake was reduced by 4% following 4 wk of SIT+BR and NT+BR (P< 0.05) but not SIT+PL. The peak work rate attained during incremental exercise increased more in SIT+BR than in SIT+PL (P< 0.05) or NT+BR (P< 0.001). The reduction in muscle and blood [lactate] and the increase in muscle pH from preintervention to postintervention were greater at 3 min of severe-intensity exercise in SIT+BR compared with SIT+PL and NT+BR (P< 0.05). However, the change in severe-intensity exercise performance was not different between SIT+BR and SIT+PL (P> 0.05). The relative proportion of type IIx muscle fibers in the vastus lateralis muscle was reduced in SIT+BR only (P< 0.05). These findings suggest that BR supplementation may enhance some aspects of the physiological adaptations to SIT.NEW & NOTEWORTHYWe investigated the influence of nitrate-rich and nitrate-depleted beetroot juice on the muscle metabolic and physiological adaptations to 4 wk of sprint interval training. Compared with placebo, dietary nitrate supplementation reduced the O2cost of submaximal exercise, resulted in greater improvement in incremental (but not severe-intensity) exercise performance, and augmented some muscle metabolic adaptations to training. Nitrate supplementation may facilitate some of the physiological responses to sprint interval training.
authors.affiliation: Sport and Health Sciences, University of Exeter, Exeter, United Kingdom.
authors.forename: Christopher
authors.initials: C
authors.lastname: Thompson
authors.affiliation: Sport and Health Sciences, University of Exeter, Exeter, United Kingdom.
authors.forename: Lee J
authors.initials: LJ
authors.lastname: Wylie
authors.affiliation: Sport and Health Sciences, University of Exeter, Exeter, United Kingdom.
authors.forename: Jamie R
authors.initials: JR
authors.lastname: Blackwell
authors.affiliation: National Institute for Health Research Exeter Clinical Research Facility, University of Exeter, Exeter, United Kingdom; and.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Fulford
authors.affiliation: Sport and Health Sciences, University of Exeter, Exeter, United Kingdom.
authors.forename: Matthew I
authors.initials: MI
authors.lastname: Black
authors.affiliation: Sport and Health Sciences, University of Exeter, Exeter, United Kingdom.
authors.forename: James
authors.initials: J
authors.lastname: Kelly
authors.affiliation: Sport and Health Sciences, University of Exeter, Exeter, United Kingdom.
authors.forename: Sinead T J
authors.initials: ST
authors.lastname: McDonagh
authors.affiliation: Gatorade Sports Science Institute, PepsiCo Research & Development, Barrington, Illinois.
authors.forename: James
authors.initials: J
authors.lastname: Carter
authors.affiliation: Sport and Health Sciences, University of Exeter, Exeter, United Kingdom.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Bailey
authors.affiliation: Sport and Health Sciences, University of Exeter, Exeter, United Kingdom.
authors.forename: Anni
authors.initials: A
authors.lastname: Vanhatalo
authors.affiliation: Sport and Health Sciences, University of Exeter, Exeter, United Kingdom; a.m.jones@exeter.ac.uk.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Jones
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000502:physiology*; D000284:Administration, Oral; D000328:Adult; D054874:Athletic Performance / Q000502:physiology; D019587:Dietary Supplements; D000072696:High-Intensity Interval Training / Q000379:methods*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology*; D009566:Nitrates / Q000008:administration & dosage*; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology*; D012420:Running / Q000502:physiology*; D013647:Task Performance and Analysis
chemical_list: D009566:Nitrates; D010100:Oxygen
keywords: beetroot juice supplementation; exercise training; muscle metabolism; training adaptation