Submitted on December 12, 2007
Revised on May 30, 2008
Accepted on June 16, 2008
EXERCISE TRAINING IMPACTS MYOCARDIAL METABOLISM OF OLDER INDIVIDUALS IN A GENDER-SPECIFIC MANNER
Pablo F. Soto1*, Pilar Herrero2, Kenneth B. Schechtman2, Alan D Waggoner, Jeffrey M. Baumstark1, Ali A. Ehsani3, and Robert J Gropler1
1 Washington University
2 Washington University School of Medicine
3 Dept. of Medicine (Cardiology)
* To whom correspondence should be addressed. E-mail: sotop{at}mir.wustl.edu.
Aging is associated with decreases in aerobic capacity, cardiac function, and insulin sensitivity as well as alterations in myocardial substrate metabolism. Endurance exercise training (EET) improves cardiac function in a gender-specific manner, and EET has been shown to improve whole-body glucose tolerance, but its effects on myocardial metabolism are unclear. Accordingly, we studied the effect of EET on myocardial substrate metabolism in older men and women. Twelve healthy older individuals (ages 60 to 75 yrs, six male) underwent PET with 15O-water, 11C-acetate, 11C-glucose, and 11C-palmitate for assessment of myocardial blood flow (MBF), oxygen consumption (MVO2), glucose utilization (MGU), and fatty acid utilization (MFAU), respectively, at rest and during dobutamine infusion (10 µg•kg-1•min-1). Measurements were repeated after 11 months of EET. VO2max increased (P = 0.005) after EET. MBF was unaffected by training, as was resting MVO2; however, post-training dobutamine MVO2 was significantly higher (P = 0.05), as was MGU (P < 0.04). Although overall dobutamine MFAU was unchanged, posttraining dobutamine MFAU increased in women (P = 0.01) but decreased in men (P = 0.03). Thus, EET in older individuals improves the catecholamine response of myocardial glucose metabolism. Moreover, gender differences exist in the myocardial fatty acid metabolic response to training. These findings suggest a role for altered myocardial substrate metabolism in modulating the cardiovascular benefits of EET in older individuals.
