Effects of Exercise on Abdominal Obesity and Risk Factors for Cardiovascular Disease

Dose-response Effects of Exercise on Abdominal Obesity and Risk Factors for CVD in Men and Women.

The investigators will randomize abdominally obese men and women at increased health risk to one of the following 4 conditions: 1) No-exercise, wait list controls (C), 2) Low volume, low intensity exercise (LVLI), 3) High volume, low intensity exercise (HVLI), 4) Low volume, high intensity exercise (LVHI).

The primary aim of the trial is to determine the effects of varying exercise dose (energy expenditure, kcal) or intensity (relative to VO2max (cardiorespiratory fitness)) on waist circumference and glucose tolerance. The investigators will test the following hypotheses: 1) That the reduction in waist circumference and improvement in glucose tolerance in response to all treatments will be greater than controls. 2) That reduction in waist circumference and improvement in glucose tolerance in HVLI and LVHI will be greater than LVLI. 3) That hypotheses 1 and 2 are true independent of gender.

Inclusion Criteria:

• Men and women between 40 and 60 years of age. The lower age range for men and women is selected to help ensure recruitment of a sample with metabolic syndrome as prevalence of metabolic syndrome is significantly related to age. The selection of 60 years for the upper age range reflects concerns we have randomizing older adults to the high intensity exercise group wherein exercise at 75-80% of maximum may be difficult to achieve, and likely to be associated with increase orthopaedic injury and thus, poor compliance. We also considered lowering the lower age range from 40 to 35 years, but decided against doing so to increase the cost-effectiveness of recruitment (e.g., ensure a higher yield of those with metabolic syndrome).
• Abdominally obese (waist circumference greater than 88 and 102 cm for women and men respectively) and NCEP-ATPIII defined Metabolic Syndrome. Abdominal obesity for non-Caucasians will be determined using values suggested by the International Diabetes Federation.
• Sedentary lifestyle (planned physical activity for the purpose of health one day per week or less).
• Weight stable (± 2 kg) for 6 months prior to the beginning of the study.
• BMI less than 40 kg/m2 (Because a lifestyle-based intervention alone for obesity reduction is ideal for persons with a BMI less than 40 kg/m2).

Exclusion Criteria:

• Physical impairment which would make the intervention very difficult, or unsafe according to the patient's physician including history of myocardial infarction, stroke, coronary bypass surgery or angioplasty in the last 6 months; peripheral artery disease, unstable angina or ischemia.
• Diabetes.
• Current smokers.
• Alcohol consumption > 21 drinks per week.
• Plans to move from the area.
• Participating in another research study.
• Clinically judged to be unsuitable for participation or adherence as determined by the participants physician.
• Inability or unwillingness to provide informed consent.
• For women, planned pregnancy in the next year.