Journal of Applied Physiology, Vol 78, Issue 6 2201-2206, Copyright © 1995 by American Physiological Society

ARTICLES

Effect of exercise on lipolytic sensitivity in endurance-trained athletes

S. Klein, E. F. Coyle and R. R. Wolfe
Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.

Studies performed in vitro suggest that an acute bout of exercise increases the lipolytic response to beta-adrenergic stimulation. We evaluated the effect of exercise on lipolytic sensitivity in vivo in five endurance-trained athletes. The rate of appearance (Ra) of glycerol in plasma, an index of whole body lipolysis, was determined during 60 min of epinephrine infusion (0.015 microgram.kg-1.min-1) on two occasions: 1) at basal resting conditions and 2) 90 min after completing 1 h of high-intensity (70% O2 uptake) cycle ergometer exercise. Total glycerol Ra during epinephrine infusion in the basal state (352 +/- 35 mumol.kg-1. 60 min-1) was not significantly different from the value obtained after high-intensity exercise (439 +/- 58 mumol.kg-1. 60 min-1). However, the increase in glycerol Ra above baseline during epinephrine infusion was lower after (30 +/- 16 mumol.kg-1. 60 min-1) than before (148 +/- 28 mumol.kg-1. 60 min-1) exercise because of the high postexercise baseline value (P < 0.05). Mean plasma free fatty acid (FFA) concentration was lower during exercise than during epinephrine infusion despite a greater rate of lipolysis during exercise. The slope of change in plasma FFA with respect to glycerol RA was lower during exercise (0.0171 +/- 0.006) than during epinephrine infusion (0.0835 +/- 0.018) (P < 0.05). We conclude that a single bout of intense exercise does not increase in vivo lipolytic sensitivity to beta-adrenergic stimulation in endurance-trained athletes. In addition, plasma FFA concentration represents the balance between plasma FFA inflow and tissue uptake and cannot be used as an index of lipolytic activity during certain physiological conditions, such as exercise.

This article has been cited by other articles:

				R. C. Boston and P. J. Moate A novel minimal model to describe NEFA kinetics following an intravenous glucose challenge Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2008; 294(4): R1140 - R1147. [Abstract] [Full Text] [PDF]

				B. Mittendorfer, J. F. Horowitz, and S. Klein Gender differences in lipid and glucose kinetics during short-term fasting Am J Physiol Endocrinol Metab, December 1, 2001; 281(6): E1333 - E1339. [Abstract] [Full Text] [PDF]

				F. Marion-Latard, I. De Glisezinski, F. Crampes, M. Berlan, J. Galitzky, H. Suljkovicova, D. Riviere, and V. Stich A single bout of exercise induces {beta}-adrenergic desensitization in human adipose tissue Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2001; 280(1): R166 - R173. [Abstract] [Full Text] [PDF]

				J. F. Horowitz and S. Klein Whole body and abdominal lipolytic sensitivity to epinephrine is suppressed in upper body obese women Am J Physiol Endocrinol Metab, June 1, 2000; 278(6): E1144 - E1152. [Abstract] [Full Text] [PDF]

				V. Stich, I. de Glisezinski, M. Berlan, J. Bulow, J. Galitzky, I. Harant, H. Suljkovicova, M. Lafontan, D. Riviere, and F. Crampes Adipose tissue lipolysis is increased during a repeated bout of aerobic exercise J Appl Physiol, April 1, 2000; 88(4): 1277 - 1283. [Abstract] [Full Text] [PDF]

				G. B. Carey Cellular adaptations in fat tissue of exercise-trained miniature swine: role of excess energy intake J Appl Physiol, March 1, 2000; 88(3): 881 - 887. [Abstract] [Full Text] [PDF]

				J. F. Horowitz, R. J. Braudy, W. H. Martin III, and S. Klein Endurance exercise training does not alter lipolytic or adipose tissue blood flow sensitivity to epinephrine Am J Physiol Endocrinol Metab, August 1, 1999; 277(2): E325 - E331. [Abstract] [Full Text] [PDF]