Varying physical activity for optimal health benefits

How hard and for how long should you exercise in order to shed excess abdominal fat and reduce your risk of cardiovascular disease?

That question - of particular interest to the more than 60 per cent of Canadians who are overweight or obese - will be investigated over the next three years by researchers at Queen's University in a new $1.8-million study funded by the Canadian Institutes of Health Research (CIHR).

It's the largest, single-site study of its kind, and is being led by exeercise physiologist Robert Ross, from Queen's School of Kinesiology and Health Studies. "For most Canadian adults, the question isn't 'How much exercise should I be doing?' but rather, 'How little can I do and still get the benefits?'" says Dr. Ross.

Current Canadian guidelines suggest 20 to 30 minutes of daily vigorous activity, such as moderate to brisk jogging, offers a wide range of health benefits. The guidelines also say that 45 to 60 minutes of walking get the same results.

"But surprisingly, there's a lack of solid evidence from randomized control trials to support this," notes Dr. Ross. "We know very little about the specific type, amount, pattern and intensity of exercise that will provide optimal or even measurable health benefits."

The Queen's study is now recruiting in the Kingston area for 320 male and female adults who carry excess weight around their stomachs. Research has shown that a higher-than-average risk factor for heart disease is associated with this abdominal obesity.

Under the supervision of university kinesthesiologists, participants will perform different levels and amounts of exercise five days a week over six months. The research team will measure the effects of varying physical activity on both waist circumference and glucose tolerance (the ability to manage blood sugar).

A nutritionist will also meet individually with participants to guide them through meal planning and food consumption, in an effort to ensure that all consume a balanced, healthy diet over the course of the study.

Dr. Ross's co-investigators are professors Robert Hudson (Endocrinology) and Miu Lam (Community Health and Epidemiology). Other members of the research team, from the School of Kinesiology and Health Studies, include: Amanda Bullock, Morgan Craig-Broadwith, Kaitlyn Hougham, Peter Janiszewski, Amanda McDougall, Ashlee McGuire, Gillianne Mundell, Tammy Scott-Zelt, Paula Stotz, Jennifer Tomasone, Kristin Toomsalu and Melinda Van Zanten

"Our entire team is honoured and excited to receive this significant funding from CIHR to investigate a health issue that affects so many people," says Dr. Ross.

"The first step will be to clearly identify the separate effects of exercise dose and intensity on obesity and related risk factors for cardiovascular disease under controlled conditions," he continues. "Only then can we develop effective lifestyle-based strategies to improve overall health."