When it comes to discussing exercise with friends, family and patients, it seems that many of us are at a loss for words. What kind of exercise should we recommend? How much exercise is enough? How much is too much? How do I know that my patient is actually exercising? How do I prescribe exercise?
According to the U.S. Department of Health and Human Services, U.S. adults should engage in moderately intense physical activity for a minimum of 150 minutes each week; this is equivalent to 30 minutes a day, 5 days per week [1]. While it is relatively easy to keep track of the duration and frequency of exercise, it is much more difficult to quantify the intensity of an activity, let alone ensure that the activity is “moderate” for the entire 30 minutes.
In fact, in a 2008 study of women’s understanding of “moderate-intensity” of physical activity as presented in the popular media, the authors found it is not enough to simply hear and read a description of physical activity, but that it requires practice [2].
So, what are we to do? Should we have our patients log their daily activities? Should we have our patients show us sign-in sheets from the local gym?
It turns out that the dilemma of how to quantify physical activity has been a hot topic for more than 50 years. In 1965, a Japanese inventor developed the first pedometer to give people the opportunity to meet measurable goals and, thus, increase their physical activity. The device was called the Manpo-Kei (meaning “10,000 steps meter”) and it was based on research by Dr. Yoshiro Hatano that demonstrated that 10,000 steps per day allowed for a proper balance between the traditional Japanese caloric intake and the activity-based caloric expenditure of walking approximately five miles per day (the average person’s stride length is approximately 2.5 feet long, therefore 2,000 steps/mile) [3].
