For about as long as I can remember, I've told people that walking a mile burns as many calories as running a mile. I have no idea where I came by this notion. Maybe it was the readout on my treadmill, which actually seems to show that I burn more calories per mile the slower I go.
In any case, it seems logical that having to move the same body weight over the same distance should require the same amount of energy, regardless of speed. Plus, I've told people this “fact” so many times that it just has to be correct. Right?
Dr. Prescott prescribes
Um, no. But nice try. Going forward, you might look for better scientific sources than a piece of fitness equipment.
In a 2004 study, researchers at Syracuse University measured the exact calorie burn of subjects who walked and ran a mile on treadmills. When walking, men burned 88 calories and women 74.
When they picked up the pace to a run, men burned 124 calories and women 105. (The men used more energy because they weighed more.)
If you think about biomechanics, it makes sense that running would burn almost 50 percent more energy.
In walking, you keep your legs straight and your center of gravity stays pretty much constant. When you run, you are jumping from one leg to another. With each jump, you're pushing your center of gravity higher, then bending your knee to absorb the impact. Fighting gravity during this constant rise and fall requires significant additional effort.
As if this weren't bad enough news for walkers, I'm going to throw another monkey wrench into the equation.
When we're talking about how much energy an activity requires, we typically (just like I did a moment ago) talk about total calorie burn. But if you really want to understand the impact of an activity, you want to look at net calorie burn.