No effect of dietary nitrate supplementation on endurance training in hypoxia

Scand J Med Sci Sports. 2015 Apr;25(2):234-41. doi: 10.1111/sms.12199. Epub 2014 Mar 20.

Abstract

We investigated whether dietary nitrate (NO(3)(-)) supplementation enhances the effect of training in hypoxia on endurance performance at sea level. Twenty-two healthy male volunteers performed high-intensity endurance training on a cycle ergometer (6 weeks, 5×30 min/week at 4-6 mmol/L blood lactate) in normobaric hypoxia (12.5% FiO(2)), while ingesting either beetroot juice [0.07 mmol NO(3)(-) /kg body weight (bw)/day; BR, n = 11] or a control drink (CON, n = 11). During the pretest and the posttest, the subjects performed a 30-min simulated time trial (TT) and an incremental VO(2max) test. Furthermore, a biopsy was taken from m. vastus lateralis before and after the TT. Power output during the training sessions in both groups increased by ∼6% from week 1 to week 6 (P < 0.05). Compared with the pretest, VO(2max) in the posttest was increased (P < 0.05) in CON (5%) and BR (9%). Power output corresponding with the 4 mmol/L blood lactate threshold, as well as mean power output during TT increased by ∼16% in both groups (P < 0.05). Muscle phospho-AMP-activated protein kinase, hypoxia inducible factor-1α mRNA content, and glycogen breakdown during the TT were similar between the groups in both the pretest and the posttest. In conclusion, low-dose dietary NO(3)(-) supplementation does not enhance the effects of intermittent hypoxic training on endurance exercise performance at sea level.

Keywords: Nitric oxide; aerobic capacity; altitude; high-intensity endurance training.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological / drug effects
  • Adaptation, Physiological / physiology
  • Adolescent
  • Adult
  • Altitude
  • Beta vulgaris*
  • Bicycling / physiology*
  • Blotting, Western
  • Dietary Supplements*
  • Exercise Test
  • Fruit and Vegetable Juices*
  • Healthy Volunteers
  • Humans
  • Hypoxia* / metabolism
  • Male
  • Muscle Proteins / metabolism
  • Nitrates / administration & dosage
  • Nitrates / pharmacology*
  • Nitrates / physiology
  • Oxygen Consumption / drug effects
  • Oxygen Consumption / physiology
  • Physical Endurance / drug effects*
  • Physical Endurance / physiology
  • Quadriceps Muscle / drug effects
  • Quadriceps Muscle / metabolism
  • Real-Time Polymerase Chain Reaction
  • Reverse Transcriptase Polymerase Chain Reaction
  • Young Adult

Substances

  • Muscle Proteins
  • Nitrates