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The Fit Can Survive

From - Rouge Valley Health System - Cardiac Rehabilitation Services - Toronto Ontario
August 2003
By Nancy Payne, Exercise Therapist

There is no denying it: exercise is good for you. Whether you have never put on a pair of running shoes to go for a walk, or they are hiding in the back of your closet, if you have heart disease, put them on and get moving - a lot! Recent research shows that exercise is more important than ever.

But if it's clear today, it hasn't always been so. As early as 1768 English physician William Heberden noted the benefits of exercise in the treatment of heart disease when his patient reported relief of angina symptoms after sawing wood daily for 30 minutes. But the message was not fully understood. Over the 100 years that followed, doctors commonly ordered complete bed rest for patients recovering from a heart attack. This inactive approach didn't get good results and in the 1950's, prompted Dr. Terry Kavanagh, physician and exercise scientist, to start supervised exercise rehabilitation for most heart patients. In 1968 he opened the Toronto Rehabilitation Centre where structured, individualized exercise prescription and heart health education were the main components of his specialized cardiac program. Graduates of Dr. Kavanagh's program reported tremendous improvements in their physical and emotional well being. Today, we've finally got it - the medical profession supports that exercise of moderate intensity is recommended for most heart patients.

How Do We Know Exercise Works?

The results of numerous studies can't be wrong. An overwhelming amount of scientific research concludes that exercise improves your health. Researchers have devised the "dose-response curve"(see Graph 1) to illustrate how this relationship works (Adapted from Sesso, H. et al. 2000). With more exercise (the dose), the amount of health benefits increase (the response). In simple terms, getting the maximum benefit from your exercise is related to the amount you do. The plateau of the curve shows that the health benefits don't continue to increase beyond a certain amount of exercise. It's somewhat like taking medication. Taking more medication than your doctor has prescribed is not better and in most cases, will be harmful.

The scientific news keeps getting better. According to a recent study published in the New England Journal of Medicine, people who get plenty of exercise live longer, even people with heart disease (Myers, J et al. 2002). In this study, 6,213 men were divided into two groups, those with and without a history of heart disease. These two groups were subdivided into one of three fitness categories (low, medium and high fitness) based on how much uphill walking they completed during an exercise stress test. The comparisons between fitness categories are shown in Graph 2 (the group without heart disease) and in Graph 3 (the group with heart disease). In both graphs, men in the high fitness group survived longer compared to men in the medium and low fitness groups. Not only that - men in the high fitness group had a lower risk of dying even in the presence of high blood pressure, diabetes and excess body weight. The authors concluded that it was the differences in fitness that prolonged the participant's lives, despite having other health conditions.

Why do we exercise?

The changes that occur in the body with regular exercise go a long way to improve the efficiency of the heart and lungs and working muscles. Habitual activity lowers resting heart rate, increases the amount of blood the heart can eject with each beat and increases the use of oxygen by working muscles. Collectively, these improvements reduce the workload of the heart. Habitual activity also lowers blood pressure, increases good HDL cholesterol and helps regulate blood sugar. Activities of daily living become easier to perform and leisure activities such as gardening will feel like a breeze (see gardening article in this issue).

So we know that exercise works but what are we doing with this knowledge? Are you getting sufficient exercise? The American College of Sports Medicine, a leading authority in the area of exercise science, recommends that adults include a 30 minute brisk walk on most, if not all, days of the week to improve their health. Following this recommendation is a good place to start if you have not had your exercising shoes on for a while. If you are new to the cardiac rehab program, 30 minutes of walking 5 times per week may be your starting prescription. But according to the dose response curve described early in this article that's just the beginning! For maximum benefit, exercise needs to be of longer duration, performed more frequently and with more effort. With this in mind, your Exercise Therapist systematically and safely changes your exercise frequency, duration and intensity at regular intervals throughout your attendance at the cardiac rehabilitation program. If your exercise routine has become less than habitual or has been interrupted by other priorities, it is time to get moving again. It is long-term compliance to your exercise program that provides greater health benefits and the required time for improvement. Participating in our upcoming "Walk With Heart" walkathon on September 27, 2003 in support of cardiac rehab services may be just the opportunity you are looking for to re-establish your walking routine. Regular exercise helps you live a longer life!

Graph 1: Dose-Response Curve (Adapted from Sesso, H. et al. 2000)
Graph 2: Survival rates for normal subjects according to peak fitness level. (Myers, J. et al. 2002)
Graph 3: Survival rates of subjects with cardiovascular disease according to peak fitness level. (Myers, J. et al. 2002)

CCRF would like to thank the Rouge Valley Health System - Cardiac Rehabilitation Services for their contribution to the website.

The articles, on the Cardiac Health Foundation of Canada website, are presented with the understanding that the Foundation is providing information only and not rendering medical advise. Please check with your family physician, specialist or health care professional before implementing any of the ideas expressed in these articles.

 
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