Kinetics of intramuscular triglyceride fatty acids in exercising humans

Z. Guo, B. Burguera, M. D. Jensen

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87 Scopus citations


A pulse ([14C]palmitate)-chase ([3H]palmitate) approach was used to study intramuscular triglyceride (imTG) fatty acid and plasma free fatty acid (FFA) kinetics during exercise at ~45% peak O2 consumption in 12 adults. Vastus lateralis muscle was biopsied before and after 90 min of bicycle exercise; 3H2O production, breath 14CO2 excretion and lipid oxidation (indirect calorimetry) rates were measured during exercise. Results: during exercise, 8.2 ± 1.2 and 8.4 ± 0.7 μmol·kg-1·min-1 of imTG fatty acids and plasma FFA, respectively, were oxidized according to isotopic measurements. The sum of these two values was not different (P =0.6) from lipid oxidation by indirect calorimetry (15.4 ± 1.6 μmol·kg-1·min-1); the isotopic and indirect calorimetry values were correlated (r = 0.79, P < 0.005). During exercise, imTG turnover rate was 0.32 ± 0.07%/min (6.0 ± 2.0 μmol of imTG·kg wet muscle-1·min-1) and plasma FFA were incorporated into imTG at a rate of 0.7 ± 0.1 μmol·kg wet muscle-1·min-1. The imTG pool size did not change during exercise. This pulse-chase, dual tracer appears to be a reasonable approach to measure oxidation and synthesis kinetics of imTG.

Original languageEnglish (US)
Pages (from-to)2057-2064
Number of pages8
JournalJournal of applied physiology
Issue number5
StatePublished - 2000


  • Body composition
  • Free fatty acids
  • [C]palmitate

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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