Exercise: How Much?

Exercise is crucially important to a healthy lifestyle and lowers the risk of cardiovascular disease.  It has beneficial effects on blood pressure, cholesterol and diabetes.  Also, there is evidence that exercise lowers the risk of dementia.  But what is the right amount of exercise?  What’s the best type of exercise?  Can exercise be dangerous?  Read on . . .

Everyone should try to exercise 150 minutes a week, broken up over 4-5 days, or about 30-40 minutes a day.  Doing it all in one day isn’t as beneficial as getting exercise most days of the week.  More exercise has diminishing returns and there is even evidence that extremely frequent exercise—for instance, 2 hours every day—starts to cause some harm.  The body needs time to recover and solidify the benefits.

Intensity also matters.  Cardiologists generally recommend moderate intensity, which is a level that would allow you to talk, but not hold a protracted conversation.  You should notice you are breathing more heavily, but not be gasping for air.  So, a casual stroll in the neighborhood would be a form of “activity,” but wouldn’t qualify as exercise.  And high intensity exercise may be good for athletic training, but is not necessary to gain the health benefits of exercise and can, in some circumstances, cause harm.

Interestingly, while people think of exercise as something you do to help the heart, it really doesn’t do that directly.  Exercise stresses the heart—making it beat faster and pump harder.  But the value to the heart is when you aren’t exercising.  The direct benefits of exercise are the adaptive changes that occur to your muscles, blood vessels and metabolism during exertion.  These adaptations lead to your cardiovascular system working more efficiently, allowing your heart to work less hard.  So, while exercise transiently increases cardiac stress (and thus risk) for the 30-40 minutes a day you are exercising, it leads to a lower stress and risk for the other 23+ hours in the day.

Follow some commonsense rules: warm up by starting gradually; have a cool down period at the end.  Avoid exercising in extremes of temperature—exercise early in the summertime and later in the winter.  Keep in mind that competitive sports add an extra layer of psychological stress beyond the physical component.  And listen to your body—stop if you are experiencing chest pressure, unusual shortness of breath, breaking into a sweat with minimal activity, or feeling faint with exertion.

People also ask me what type of exercise they should do—my answer is to do the type of exercise that you will continue to do!  The differences to your health between various machines or activities is not enough to make that the decisive factor.  Examples of moderate exercise include brisk walking or easy jogging, doubles tennis, dancing, swimming or water aerobics, bike riding (stationary or outdoors), and elliptical training.  Your choice should be based on what you enjoy and what is least taxing to your joints if you have such limitations.

One thing I strongly recommend—if you have generally been inactive and want to start exercising more vigorously, speak with your health care provider first, who can determine if it’s safe to start or if you should perhaps have a treadmill test beforehand.  But you don’t need to see your doctor just to start walking.  While it might not qualify as exercise per se, any activity is better than none—so get going!

Greg Koshkarian, MD, FACC

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Gregory Koshkarian, MD, FACC