Intensity of Physical Activity

Even when we sit and seemingly do nothing, our body still expends (burns) energy. This happens due to the fact that many organs, such as the heart, the lungs, the brain must work continuously to keep us alive. If we were to walk or run then our body would have to use even more energy than if we were just sitting, resting. But how much more? 

Scientists introduced a relative unit of measurement for energy expenditure they called Metabolic Equivalent of Task or MET for short. We assume for simplicity’s sake that 1 MET equals the amount of energy spent by a person while sitting and doing nothing for a certain period of time, let’s say an hour. If this same person got up and walked for an hour, he or she would’ve spent roughly 3 times the amount of energy spent while sitting. In other words, this activity (walking) is measured at 3 METs.

By using the relative measure of energy exertion for various physical activities, we can categorize these activities by light, moderate and vigorous:

Light Intensity Activities	0-2.9 METs
Moderate Intensity Activities	3-5.9 METs
Vigorous Intensity Activities	6-10 METs

Now you should be able to translate the recommendations of the U.S. Department of Health into specific activities that would help you to meet the minimum requirements for regular physical activity. So, if you wanted to improve your health you could start speed walking. Knowing that walking with the pace of 4 mph is a moderate intensity activity, which converts into 2.5 to 5 hours a week (it’s only 30 to 60 minutes a day, 5 days a week). If you’d rather play sports or hike… Hold on! Why don’t you practice what you just learned about the intensity levels? Try to figure out what intensity level your favorite activities would be categorized under. Google for things like “Metabolic Equivalent of playing tennis” or even “Metabolic Equivalent of cleaning a house.”

You can always refer to the list of general physical activities defined by level of intensity provided by the Centers for Disease Control and Prevention if you need to approximate the intensity level of the physical activity you will be performing.