Acute supplementation of N-acetylcysteine does not affect muscle blood flow and oxygenation characteristics during handgrip exercise

Physiol Rep. 2016 Apr;4(7):e12748. doi: 10.14814/phy2.12748.

Abstract

N-acetylcysteine (NAC; antioxidant and thiol donor) supplementation has improved exercise performance and delayed fatigue, but the underlying mechanisms are unknown. One possibility isNACsupplementation increases limb blood flow during severe-intensity exercise. The purpose was to determine ifNACsupplementation affected exercising arm blood flow and muscle oxygenation characteristics. We hypothesized thatNACwould lead to higher limb blood flow and lower muscle deoxygenation characteristics during severe-intensity exercise. Eight healthy nonendurance trained men (21.8 ± 1.2 years) were recruited and completed two constant power handgrip exercise tests at 80% peak power until exhaustion. Subjects orally consumed either placebo (PLA) orNAC(70 mg/kg) 60 min prior to handgrip exercise. Immediately prior to exercise, venous blood samples were collected for determination of plasma redox balance. Brachial artery blood flow (BABF) was measured via Doppler ultrasound and flexor digitorum superficialis oxygenation characteristics were measured via near-infrared spectroscopy. FollowingNACsupplementaiton, plasma cysteine (NAC: 47.2 ± 20.3 μmol/L vs.PLA: 9.6 ± 1.2 μmol/L;P = 0.001) and total cysteine (NAC: 156.2 ± 33.9 μmol/L vs.PLA: 132.2 ± 16.3 μmol/L;P = 0.048) increased. Time to exhaustion was not significantly different (P = 0.55) betweenNAC(473.0 ± 62.1 sec) andPLA(438.7 ± 58.1 sec). RestingBABFwas not different (P = 0.79) withNAC(99.3 ± 31.1 mL/min) andPLA(108.3 ± 46.0 mL/min).BABFwas not different (P = 0.42) during exercise or at end-exercise (NAC: 413 ± 109 mL/min;PLA: 445 ± 147 mL/min). Deoxy-[hemoglobin+myoglobin] and total-[hemoglobin+myoglobin] were not significantly different (P = 0.73 andP = 0.54, respectively) at rest or during exercise between conditions. We conclude that acuteNACsupplementation does not alter oxygen delivery during exercise in men.

Keywords: Blood flow; N ‐acetylcysteine; vasodilation.

Publication types

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

MeSH terms

  • Acetylcysteine / administration & dosage*
  • Administration, Oral
  • Biomarkers / blood
  • Blood Flow Velocity / drug effects
  • Brachial Artery / diagnostic imaging
  • Brachial Artery / drug effects*
  • Brachial Artery / physiology
  • Cross-Over Studies
  • Dietary Supplements*
  • Double-Blind Method
  • Exercise Test
  • Exercise*
  • Hand Strength*
  • Hemoglobins / metabolism
  • Humans
  • Male
  • Muscle Fatigue
  • Muscle, Skeletal / blood supply
  • Muscle, Skeletal / drug effects*
  • Muscle, Skeletal / metabolism
  • Myoglobin / metabolism
  • Oxygen / blood*
  • Oxygen Consumption / drug effects
  • Physical Endurance / drug effects*
  • Regional Blood Flow / drug effects
  • Spectroscopy, Near-Infrared
  • Time Factors
  • Ultrasonography, Doppler
  • Vasodilation / drug effects
  • Young Adult

Substances

  • Biomarkers
  • Hemoglobins
  • Myoglobin
  • deoxyhemoglobin
  • Oxygen
  • Acetylcysteine