title: Dose-response effects of exercise on abdominal obesity and risk factors for cardiovascular disease in adults: study rationale, design and methods.
abstract: Although progress has been made to elucidate the effects of exercise as a strategy for reducing obesity and related cardiometabolic risk factors, the specific exercise exposures required to achieve optimal benefit continue to be the source of considerable uncertainty and debate. Despite the inference of a dose-dependent relationship between exercise and health benefit, absent from the literature are randomized trials that, without alteration in caloric intake, examine the separate effects of exercise dose and intensity on obesity and associated cardiometabolic risk. We will perform a randomized, controlled trial designed to study the separate effects of habitual exercise differing in dose (energy expenditure, kcal/session) and intensity (relative to VO(2)peak) on abdominal obesity and selected cardiometabolic risk factors. The primary outcomes are waist circumference and 2-hour glucose. We will randomly assign 320 sedentary, abdominally obese men (N=160) and women (N=160) to one of 4 conditions: 1) no-exercise control, 2) low volume, low intensity exercise, 3) high volume, low intensity exercise, and 4) high volume, high intensity exercise. Duration of all treatments will be 6 months. The findings from this study may help resolve the following unanswered questions, "For a given exercise dose does higher exercise intensity result in greater health benefits?" "For a given exercise intensity does higher exercise dose result in greater health benefits?". Identification of the separate effects of exercise dose and intensity on obesity and related cardiometabolic risk factors under controlled conditions is important for development of optimal, lifestyle-based strategies that can subsequently be tested in long-term effectiveness trials.
authors.affiliation: School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada. rossr@queensu.ca
authors.forename: Robert
authors.initials: R
authors.lastname: Ross
authors.forename: Robert
authors.initials: R
authors.lastname: Hudson
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Day
authors.forename: Miu
authors.initials: M
authors.lastname: Lam
mesh_terms: D000328:Adult; D000368:Aged; D002318:Cardiovascular Diseases / Q000209:etiology / Q000517:prevention & control*; D015444:Exercise / Q000502:physiology*; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D056128:Obesity, Abdominal / Q000150:complications / Q000628:therapy*; D012307:Risk Factors