Effect of glycerol feeding on endurance and metabolism during prolonged exercise in man

Med Sci Sports Exerc. 1983;15(3):237-42.

Abstract

This study evaluated the effectiveness of pre-exercise glycerol feeding in protecting against development of hypoglycemia and sparing muscle glycogen during prolonged, intense exercise. Thirty minutes after ingesting either glycerol (1 gm X kg-1 body weight) or a placebo, 10 cyclists performed as much exercise on a cycle ergometer as they were able in 150 min. The average exercise intensity was 72% of VO2max during both trials. Glycerol ingestion increased blood glycerol concentration 100-fold, but did not alter the respiratory exchange ratio (R), plasma levels of insulin and free-fatty acids, or blood lactate and beta-hydroxybutyrate. The only significant effect of glycerol feeding was to postpone the decline in blood glucose by about 30 min. This suggests that glycerol served, to a limited extent, as a gluconeogenic substrate; however, glycerol ingestion did not spare muscle glycogen during 90 min of treadmill exercise at 71% VO2max. It appears that man cannot utilize glycerol as gluconeogenic substrate rapidly enough to serve as a major energy source during strenuous exercise.

Publication types

  • Clinical Trial
  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Administration, Oral
  • Adult
  • Clinical Trials as Topic
  • Double-Blind Method
  • Exercise Test*
  • Female
  • Glycerol / administration & dosage
  • Glycerol / pharmacology*
  • Glycogen / metabolism*
  • Humans
  • Hypoglycemia / prevention & control
  • Male
  • Muscles / metabolism*
  • Physical Endurance / drug effects*
  • Random Allocation
  • Sports Medicine*
  • Time Factors

Substances

  • Glycogen
  • Glycerol