How Active is Active Enough?

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Bob Murray, Exercise Physiologist, Ph.D., FACSM
Former Director, Gatorade Sports Science Institute
Principal, Sports Science Insights

Science now confirms what people long suspected

exercise is potent medicine.

Simply put, no prescription medication or dietary supplement is powerful enough to produce the myriad benefits of regular physical activity.  Whether you prefer to call it training, working out, exercising, being active, or just plain moving, almost anything you do beyond being a couch potato will benefit your health.  Not surprisingly, when it comes to health benefits, more activity is better than less activity, but just how active is active enough?

The answer to that question can be found in the 2008 Physical Activity Guidelines for Americans (  Developed by a panel of 13 experts in exercise and health working under the auspices of the U.S. Department of Health and Human Services, these are the first guidelines for physical activity issued by the U.S. government.  The core recommendation is simple and straightforward:

Most health benefits occur with at least 150 minutes a week of moderate-intensity physical activity, such as brisk walking. Additional benefits occur with more physical activity.”

mark sebastian/

mark sebastian/

What are the benefits?

The documented benefits of regular physical activity are many: lower risk of early death, coronary heart disease, stroke, high blood pressure, type 2 diabetes, metabolic syndrome (a group of maladies including obesity, diabetes, and hypertension), colon cancer, and breast cancer.  Physically active people are generally fitter, thinner, stronger, and less prone to falls and depression.

Setting aside those clinical benefits, the lifestyle benefits are perhaps even more compelling.  Being fit and healthy gives us the energy to maintain our hobbies (and start new ones), participate in other physical activities (such as jumping into a pick-up game of basketball), keep up with the kids, sleep better, and just squeeze more enjoyment out of life.



What constitutes exercise?

Many people reflexively grimace when they hear the word “exercise” because it conjures up unpleasant memories from PE classes long past, the lingering guilt from a lapsed membership at the local health club, the home exercise equipment that now serves as a clothes rack, or off-putting images of super-intense exercise from TV programs such as “The Biggest Loser.”  But exercise is nothing more than simply moving your body and there are many ways to get that done.

Walking, dancing, hiking, and yard work can be just as effective as jogging, swimming, biking, weight lifting, or fitness classes in making you active enough to improve your fitness and trim your waistline.  The whole idea is to simply move more during the day; that alone is often enough to spark the lifestyle changes that lead to even bigger benefits.

Part of the beauty of just moving more each day is that there is no need to commit to just one type of physical activity.  You could walk, garden, and dance one day, and then bike, cut the grass, and lift weights the next.  If you like to play games, touch football, softball, soccer, and basketball all qualify.  Any combination of physical activity that gets you moving long enough will benefit your health.



How much physical activity is enough?

The goal is to move your body at least 2 ½ hours (150 minutes) each week or vigorous just 1 ¼ hours (75 minutes) if you enjoy more vigorous activity.  Seventy-five minutes of physical activity in a week is only about 10 minutes each day, so even the most time-challenged individuals have no excuse for failing to reach the minimum.

Keep in mind that devoting more time to physical activity produces more health benefits.  Set the bar high and enjoy the results.



How vigorous is vigorous enough?

How intense should physical activity be to produce health benefits? Most physicians and scientists recommend at least 500 MET-minutes each week.  To which we say, “huh?!”

Here’s the MET scoop: one MET, (which is shorthand for “metabolic equivalent” and has absolutely nothing to do with opera or baseball), refers to the energy expenditure of sitting still.

Two METs is twice the energy expenditure of rest; 3 METs is three times, and so on.  Moderate-intensity exercise is characterized as 3-6 METs and vigorous-intensity exercise is anything over 6 METs.  For example, walking at 3 mph is considered a moderate-intensity activity because it falls between 3-6 METs.  Running at 10 minutes per mile is considered vigorous intensity because it is greater than 6 METs.  If you walked at 3.5 METs for 20 minutes, you would have accomplished 70 MET-minutes (3.5 x 20).  Confused yet?

Fortunately, there is a simpler way to determine how vigorously you should move about.  Imagine a straight line with 0 on the bottom and 10 on the top; 0 is the intensity of sitting still and 10 is an all-out, gut-busting effort.  Moderate-intensity exercise is a 5 or 6 on this scale, while vigorous-intensity is a 7 or 8.  Making that subjective assessment each time you are physically activity quickly becomes second nature and is the easiest way to ensure that you are moving vigorously enough.

Enough is enough

Mark Twain supposedly said, “Whenever I feel the urge to exercise, I lie down until it goes away.”  Twain died in 1910 at age 74, a fairly long life even by today’s standards.  Although Mark Twain may have lived a sedentary lifestyle by his definition, the daily routines for people in the 1800s and early 1900s were filled with various types of physical activity, not the least of which was a lot of walking.  For most people, life required a lot of MET-minutes just to get through the day.

Everything about the health benefits of exercise can be summed up in two words: avoid inactivity.  If you don’t like to exercise or train or work out, just keep your body moving as much as possible during the day.  Moving is powerful medicine as long as you remember to take it.


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