How would you respond if I asked, “Why do you exercise?” Would you pause and ponder? Would you say “because it feels good”? Or would it be something along the lines of “I exercise to extend my life”? Most of the responses I have been given over the years fall into two general categories, those of “Because I am training for something” and “I want to lose weight.” Rarely do people respond that they exercise to extend their lives. This may be a thought in the back of their minds, especially if, for example, a family member has been diagnosed with heart disease and their is a strong family history of this condition.
This thought of heard disease lurks in the back of my mind as both maternal grandparents died due to heart disease and my mother has a few heart issues over the years. I also think about the Alzheimer’s my father battles. Will my exercise help stave off both? In the far reaches of my mind, I hope so. However, if I am honest with myself, this is not what drives me to exercise. My drive comes from a lifelong battle with weight. This battle is what most likely led me to my profession and my interest in why we eat. Yet more on the surface, this battle is the force behind my exercise patterns. Exercise does make me feel good, I get down without it. I like to practice what I preach and it is easier to encourage others when you actively take part.
These were my thoughts as I saw the question posed to Gretchen Reynolds this week in the New York Times: If I do 30 minutes of cardio exercise six days a week, would increasing it to 60 minutes a day be twice as good for me? Her response intrigued me. The answer all depends on the definition of “good.”
In her response, Ms. Reynolds, whom I enjoy reading and have high respect for, focused on lifespan as the definition of good. Studies are cited that state those exercising moderately live just as long as those who exercise obsessively. Bump your workout from 15 minutes a day to 30 minutes a day and you only see a 4% increase in lifespan. So it would seem doubling your workout time doesn’t give you much bang for you buck.
However, is there another way to look at it? Double your workout time from 30 to 60 minutes and you will burn more calories, perhaps leading to more meaningful weight loss provided you don’t eat more (we will present work out of our lab next month at the American College of Sports Medicine Meeting that shows when people exercise vigorously, they overestimate their calorie expenditure by nearly 20%, thus the idea of eating too much when you exercise more). You’ll also simply move more and sit less. And we know how important moving, even just standing, is.
So it all depends on the definition of “good.” Why do I exercise? So I can eat more and maintain an edge in my battle with weight. Why do most people exercise? Weight related responses reign supreme. Perhaps by taking an active role in our health and moving as much as we can, we gain something more that immeasurable increases in lifespan.