USC Center for Transdisciplinary Research on Energetics and Cancer or Obesity-Related Metabolic Disease Risk: Response to Exercise in Minority Youth

A.1 Aims

The overall goal of this project is to examine role of strength training as a therapeutic intervention to improve the cancer and obesity-related metabolic risk profile in African-American adolescents. The project is prompted by the urgent public health need to prevent and treat cancer and obesity-related problems, including diabetes and cardiovascular disease, in African-American adolescents, a population that is understudied and medically under-served in the Los Angeles area. A recent report from the Institute of Medicine underscored this major public health concern in the childhood obesity field:

"Children's health has made tremendous strides over the past century. In general, life expectancy has increased by more than thirty years since 1900 and much of this improvement is due to the reduction of infant and early childhood mortality. Given this trajectory toward a healthier childhood, the investigators begin the 21st century with a shocking development - an epidemic of obesity in children and youth. The increased number of obese children throughout the US during the past 25 years has led policymakers to rank it as one of the most critical public health threats of the 21st century. (92)" Obesity and metabolic syndrome problems disproportionately affect African-American adolescents (51). This project will explore why African-Americans have greater cancer risk than Hispanics (91), despite a reduced prevalence of the metabolic syndrome (7, 62).

Preliminary work from this laboratory has shown that both African-American and Hispanic children are more insulin resistant than Caucasian children, and this difference is apparently not explained by differences in body fatness. Moreover, the metabolic compensation to a similar degree of insulin resistance markedly differs between African-American and Hispanic children (62). African-Americans display greater hyperinsulinemia in response to a glucose challenge, whereas Hispanics have a more subdued increase in insulin levels due to an increase in second phase insulin secretion. The investigators will have the opportunity to build upon this preliminary work to examine the effects of resistance training on three factors predictive of cancer and metabolic disease risk: 1) body fat distribution; 2) insulin resistance and 3) measures of oxidative stress in African America adolescents. The investigators previously studying Hispanic adolescents in a parallel protocol.

The overall hypotheses of this project are that: (1) hyperinsulinemia in overweight African-American youth is associated with increased long-term cancer risk; and (2) insulin resistance, obesity and oxidative stress in overweight African-American youth will be improved with chronic resistance training and a modified carbohydrate dietary approach. The investigators will specifically examine the following metabolic outcomes, because they have been hypothesized to contribute to the obesity-related increase in cancer and metabolic disease risk: