Int J Sports Med 2013; 34(08): 695-699
DOI: 10.1055/s-0032-1327659
Physiology & Biochemistry
© Georg Thieme Verlag KG Stuttgart · New York

Age Attenuates Leucine Oxidation after Eccentric Exercise

E. L. Kullman
1   Cleveland Clinic, Pathobiology, Cleveland, United States
,
W. W. Campbell
2   Department of Nutrition Science, Purdue University, West Lafayette, United States
,
R. K. Krishnan
3   Internal Medicine, New York University Medical Center, New York, United States
,
K. E. Yarasheski
4   Internal Medicine, Washington University School of Medicine, St. Louis, United States
,
W. J. Evans
5   GlaxoSmithKline, Muscle Metabolism Drug Performance Unit, Research Triangle Park, United States
,
J. P. Kirwan
1   Cleveland Clinic, Pathobiology, Cleveland, United States
› Author Affiliations
Further Information

Publication History



accepted after revision 17 September 2012

Publication Date:
16 January 2013 (online)

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Abstract

Aging may alter protein metabolism during periods of metabolic and physiologic challenge. The purpose of this study was to assess the effects of age on whole-body amino acid turnover in response to eccentric exercise and hyperglycemia-induced hyperinsulinemia. 16 healthy men were divided into young (N=8) and older (N=8) groups. Protein metabolism was assessed using a [1-13C]-leucine isotopic tracer approach. Measures were obtained under fasted basal conditions and during 3-h hyperglycemic clamps that were performed without (control) and 48 h after eccentric exercise. Exercise reduced leucine oxidation in the younger men (P<0.05), but not in older men. Insulin sensitivity was inversely correlated with leucine oxidation (P<0.05), and was lower in older men (P<0.05). Healthy aging is associated with an impaired capacity to adjust protein oxidation in response to eccentric exercise. The decreased efficiency of protein utilization in older men may contribute to impaired maintenance, growth, and repair of body tissues with advancing age.