The long-term objective of this research program is to understand how behavioral factors such as physical activity can modify risk for cardiovascular disease, including diabetes. Type 2 diabetes has been increasing in children, suggesting that prevention efforts are needed during childhood. Insulin resistance (i.e., low insulin sensitivity), a central feature of type 2 diabetes, is associated with sedentary behavior, poor aerobic fitness, general and visceral adiposity, hypertension, inflammation, hemostatic dysfunction, dyslipidemia, African-American ethnicity, and arteriosclerosis risk. Increased physical activity results in reduced risk of diabetes and cardiovascular disease in adults. No experimental studies have examined dose-response relationships of exercise with insulin sensitivity and related health indicators in children. This application is a randomized, controlled dose-response trial to determine the effect of 4 mo of intensive physical training at two dose levels (40 min aerobic exercise, 5d/wk vs. 20 min, 5d/wk) on insulin sensitivity (via oral glucose tolerance test) in 240 overweight, sedentary African-American and white boys and girls in third grade.
The specific aims of the study test the hypotheses that the high-dose group will improve more than the low-dose group, which is expected to improve relative to controls. Improvements in body composition (% body fat, visceral fat) and aerobic fitness will be tested to see whether they can account for improvements in insulin sensitivity. Additional aims of the study will explore the effects of exercise dose on factors associated with insulin resistance and cardiovascular risk (blood pressure, lipid/lipoprotein measures, C-reactive protein, fibrinogen), and whether the change in insulin sensitivity can account for any such improvements. Ethnic and sex differences in response to intervention will be assessed. It is possible that the stimulation of insulin sensitivity takes place within the first 20 min of exercise each day and greater amounts of exercise are unnecessary (a threshold effect). The youths assigned to the longer-duration sessions may have difficulty maintaining the high-intensity exercise, with the result that they do not actually engage in a greater volume of exercise per session. By monitoring heart rate, we will be able to see if this occurs. Since so little is known in children about this important aspect of exercise dose, this project promises to contribute substantially to our understanding of how much exercise to recommend to obese youths in order to enhance their fitness, body composition and health comparison of effects of these different volumes of exercise would provide evidence for best practice guidelines and assist in designing large-scale health promotion programs for children.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK060692-02
Application #
6752463
Study Section
Epidemiology and Disease Control Subcommittee 2 (EDC)
Program Officer
Linder, Barbara
Project Start
2003-06-01
Project End
2007-04-30
Budget Start
2004-05-01
Budget End
2005-04-30
Support Year
2
Fiscal Year
2004
Total Cost
$598,589
Indirect Cost
Name
Medical College of Georgia (MCG)
Department
Pediatrics
Type
Schools of Medicine
DUNS #
966668691
City
Augusta
State
GA
Country
United States
Zip Code
30912
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Davis, Catherine L; Tingen, Martha S; Jia, Jenny et al. (2016) Passive Smoke Exposure and Its Effects on Cognition, Sleep, and Health Outcomes in Overweight and Obese Children. Child Obes 12:119-25
Pollock, Norman K (2015) Childhood obesity, bone development, and cardiometabolic risk factors. Mol Cell Endocrinol 410:52-63
Dennis, B Adam; Ergul, Adviye; Gower, Barbara A et al. (2013) Oxidative stress and cardiovascular risk in overweight children in an exercise intervention program. Child Obes 9:15-21
Davis, Catherine L; Waller, Jennifer L; Pollock, Norman K (2013) Exercise for overweight children and diabetes risk--reply. JAMA 309:133-4
Davis, Catherine L; Pollock, Norman K; Waller, Jennifer L et al. (2012) Exercise dose and diabetes risk in overweight and obese children: a randomized controlled trial. JAMA 308:1103-12
Best, John R; Miller, Patricia H; Naglieri, Jack A (2011) Relations between Executive Function and Academic Achievement from Ages 5 to 17 in a Large, Representative National Sample. Learn Individ Differ 21:327-336
Davis, Catherine L; Cooper, Stephanie (2011) Fitness, fatness, cognition, behavior, and academic achievement among overweight children: do cross-sectional associations correspond to exercise trial outcomes? Prev Med 52 Suppl 1:S65-9
Pollock, Norman K; Bernard, Paul J; Gower, Barbara A et al. (2011) Lower uncarboxylated osteocalcin concentrations in children with prediabetes is associated with beta-cell function. J Clin Endocrinol Metab 96:E1092-9
Davis, Catherine L; Tomporowski, Phillip D; McDowell, Jennifer E et al. (2011) Exercise improves executive function and achievement and alters brain activation in overweight children: a randomized, controlled trial. Health Psychol 30:91-8

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