AJP - Endocrinology and Metabolism, Vol 271, Issue 6 E983-E989, Copyright © 1996 by American Physiological Society

ARTICLES

Fat and carbohydrate metabolism during exercise in elderly and young subjects

S. Sial, A. R. Coggan, R. Carroll, J. Goodwin and S. Klein
Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.

We evaluated the effect of aging on fat and carbohydrate metabolism during moderate intensity exercise. Glycerol, free fatty acid (FFA), and glucose rate of appearance (Ra) in plasma and substrate oxidation were determined during 60 min of cycle ergometer exercise in six elderly (73 +/- 2 yr) and six young adults (26 +/- 2 yr) matched by gender and lean body mass. The elderly group was studied during exercise performed at 56 +/- 3% of maximum oxygen uptake, whereas the young adults were studied during exercise performed at the same absolute and at a similar relative intensity as the elderly subjects. Mean fat oxidation during exercise was 25-35% lower in the elderly subjects than in the young adults exercising at either the same absolute or similar relative intensities (P < 0.05). Mean carbohydrate oxidation in the elderly group was 35% higher than the young adults exercising at the same absolute intensity (P < 0.001) but 40% lower than the young adults exercising at the same relative intensity (P < 0.001). Average FFA Ra in the elderly subjects was 85% higher than in the young adults exercising at the same absolute intensity (P < 0.05) but 35% lower than the young adults exercising at a similar relative intensity (P < 0.05). We conclude that fat oxidation is decreased while carbohydrate oxidation is increased during moderate intensity exercise in elderly men and women. The shift in substrate oxidation was caused by age-related changes in skeletal muscle respiratory capacity because lipolytic rates and FFA availability were not rate limiting in the older subjects.

This article has been cited by other articles:

				E. L. Melanson, W. T. Donahoo, G. K. Grunwald, and R. Schwartz Changes in 24-h substrate oxidation in older and younger men in response to exercise J Appl Physiol, November 1, 2007; 103(5): 1576 - 1582. [Abstract] [Full Text] [PDF]

				R. R Wolfe The underappreciated role of muscle in health and disease. Am. J. Clinical Nutrition, September 1, 2006; 84(3): 475 - 482. [Abstract] [Full Text] [PDF]

				J. Kerner, P. J. Turkaly, P. E. Minkler, and C. L. Hoppel Aging skeletal muscle mitochondria in the rat: decreased uncoupling protein-3 content Am J Physiol Endocrinol Metab, November 1, 2001; 281(5): E1054 - E1062. [Abstract] [Full Text] [PDF]

				K. H. W. Lange, J. Lorentsen, F. Isaksson, A. Juul, M. H. Rasmussen, N. J. Christensen, J. Bulow, and M. Kjar Endurance training and GH administration in elderly women: effects on abdominal adipose tissue lipolysis Am J Physiol Endocrinol Metab, June 1, 2001; 280(6): E886 - E897. [Abstract] [Full Text] [PDF]

				B. Morio, J.-F. Hocquette, C. Montaurier, Y. Boirie, C. Bouteloup-Demange, C. McCormack, N. Fellmann, B. Beaufrere, and P. Ritz Muscle fatty acid oxidative capacity is a determinant of whole body fat oxidation in elderly people Am J Physiol Endocrinol Metab, January 1, 2001; 280(1): E143 - E149. [Abstract] [Full Text] [PDF]

				B. W. Patterson, G. Zhao, N. Elias, D. L. Hachey, and S. Klein Validation of a new procedure to determine plasma fatty acid concentration and isotopic enrichment J. Lipid Res., November 1, 1999; 40(11): 2118 - 2124. [Abstract] [Full Text]

				S. Sial, A. R. Coggan, R. C. Hickner, and S. Klein Training-induced alterations in fat and carbohydrate metabolism during exercise in elderly subjects Am J Physiol Endocrinol Metab, May 1, 1998; 274(5): E785 - E790. [Abstract] [Full Text] [PDF]