Training-induced alterations in fat and carbohydrate metabolism during exercise in elderly subjects

Shahid Sial, Andrew R. Coggan, Robert C. Hickner, Samuel Klein

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Compared with young adults, fat oxidation is lower in elderly persons during endurance exercise performed at either the same absolute or relative intensity. We evaluated the effect of 16 wk of endurance training on fat and glucose metabolism during 60 min of moderate intensity exercise [50% of pretraining peak oxygen consumption (̇o(2peak))] in six elderly men and women (74 ± 2 yr). Training caused a 21% increase in mean ̇o(2peak). The average rate of fat oxidation during exercise was greater after (221 ± 28 μmol/min) than before (166 ± 17 μmol/min) training (P = 0.002), and the average rate of carbohydrate oxidation during exercise was lower after (3,180 ± 461 μmol/min) than before (3,937 ± 483 μmol/min) training (P = 0.003). Training did not cause a significant change in glycerol rate of appearance (R(a)), free fatty acid (FFA) R(a), and FFA rate of disappearance during exercise. However, glucose R(a) during exercise was lower after (1,027 ± 95 μmol/min) than before (1,157 ± 69 μmol/min) training (P = 0.01). These results demonstrate that a 16-wk period of endurance training increases fat oxidation without a significant change in lipolysis (glycerol R(a)) or FFA availability (FFA R(a)) during exercise in elderly subjects. Therefore, the training-induced increase in fat oxidation during exercise is likely related to alterations in skeletal muscle fatty acid metabolism.

Original languageEnglish
Pages (from-to)E785-E790
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Issue number5 37-5
StatePublished - May 1 1998


  • Aging
  • Free fatty acids
  • Glucose
  • Glycerol
  • Stable isotopes

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