Advancing age is associated with insulin resistance, glucose intolerance, and Type 2 diabetes. Regular higher-intensity aerobic exercise reduces insulin resistance and lowers the risk of Type 2 diabetes. Nonetheless, recent cross-sectional data, based on ACSM/CDC physical activity recommendations for moderate-intensity activity on most if not all days of the week (i.e., 1000 kcal/wk), demonstrate that insulin levels are lower with regular moderate-intensity activity in middle-aged adults, suggesting a reduction in insulin resistance. Despite these cross-sectional data, few well-controlled prospective studies have determined if these recommendations are appropriate to reduce insulin resistance in the elderly. Because higher-intensity aerobic exercise is not practical for a large percentage of the elderly, data are needed to determine the efficacy of moderate-intensity exercise on reducing insulin resistance. Therefore, the primary aim of this study will be to examine the influence of 1000 kcal/wk of moderate versus higher-intensity aerobic exercise on insulin-simulated glucose disposal. A secondary aim will examine if moderate and higher-intensity aerobic exercise differentially influence non-exercising activity. Recent data in the elderly suggest that regular higher-intensity activities may reduce non-exercising activity during rest of the day. We will recruit 57, 65-90 y old women and men, who will be randomized into one of the following three groups: 1) Moderate-intensity activity (1000 kcal/wk at 50 percent VO2peak; 2) Higher-intensity activity (1000 kcal/wk at 75 percent VO2peak); 3) Control. Subjects will complete 12 wk of aerobic cycling with pre and post-testing for insulin-stimulated glucose disposal via the hyperinsulinemic/euglycemic clamp, glucose tolerance by an OGTT, and body composition using dual energy x-ray absorptiometry. Physical activity levels will be assessed by structured questionnaire every 3 weeks. Our primary hypothesize is that 1000 kcal/wk of moderate or higher-intensity activity will be equally effective decreasing insulin resistance in the elderly. Our secondary hypothesis is that higher-intensity activity will decrease non-exercising physical activity in the elderly. This New Investigator application will provide data to base future aerobic exercise recommendations in elderly adults.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
5R01AG019346-02
Application #
6532563
Study Section
Geriatrics and Rehabilitation Medicine (GRM)
Program Officer
Premen, Andre J
Project Start
2001-09-30
Project End
2004-07-31
Budget Start
2002-09-01
Budget End
2003-07-31
Support Year
2
Fiscal Year
2002
Total Cost
$210,628
Indirect Cost
Name
University of Arkansas for Medical Sciences
Department
Other Health Professions
Type
Schools of Medicine
DUNS #
City
Little Rock
State
AR
Country
United States
Zip Code
72205
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Yeo, Sophie E; Hays, Nicholas P; Dennis, Richard A et al. (2007) Fat distribution and glucose metabolism in older, obese men and women. J Gerontol A Biol Sci Med Sci 62:1393-401
Coker, Robert H; Hays, Nicholas P; Williams, Rick H et al. (2006) Exercise-induced changes in insulin action and glycogen metabolism in elderly adults. Med Sci Sports Exerc 38:433-8
Evans, William J (2002) Effects of exercise on senescent muscle. Clin Orthop Relat Res :S211-20