Strenuous endurance training increases lipolysis and triglyceride-fatty acid cycling at rest

J. A. Romijn, S. Klein, E. F. Coyle, L. S. Sidossis, R. R. Wolfe

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Abstract

Basal whole body lipid kinetics were evaluated in nine endurance-trained cyclists and 10 untrained healthy controls. The rate of appearance (Ra) of glycerol (an index of whole body lipolysis), the Ra of palmitate (an index of fatty acid release), and the rate of triglyceride-fatty acid cycling (reesterification of fatty acids released during lipolysis) were determined by infusing [2H5]glycerol and [2H2]palmitate in conjunction with indirect calorimetry. All subjects were studied while they were at rest after fasting overnight. Glycerol Ra and free fatty acid Ra in the athletes (7.33 ± 0.68 and 14.88 ± 1.35 μmol · kg-1 · min-1, respectively) were two- to threefold higher than the values in untrained control subjects (2.53 ± 0.15 and 7.64 ± 0.92 μmol · kg-1 · min-1, respectively; P < 0.02). The total rate of triglyceride-fatty acid cycling was approximately fourfold higher in the athletes (16.86 ± 2.07 μmol · kg-1 · min-1) than in the control subjects (3.91 ± 0.36 μmol · kg-1 · min-1). Plasma concentrations of insulin and catecholamines, hormones that regulate whole body lipid kinetics, were the same in both groups. We conclude that resting basal lipid kinetics are markedly increased in athletes involved in strenuous endurance training and that this enhances the potential for increasing fatty acid oxidation rapidly at the onset of exercise.

Original languageEnglish (US)
Pages (from-to)108-113
Number of pages6
JournalJournal of Applied Physiology
Volume75
Issue number1
StatePublished - 1993

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Keywords

  • lipid metabolism
  • mass spectrometry
  • stable isotopes

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Romijn, J. A., Klein, S., Coyle, E. F., Sidossis, L. S., & Wolfe, R. R. (1993). Strenuous endurance training increases lipolysis and triglyceride-fatty acid cycling at rest. Journal of Applied Physiology, 75(1), 108-113.