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.
Your body burns calories all the time, even while you're sitting on your duff reading this column. So to measure the true effect of a workout, you take the number of calories you burned while exercising and subtract those calories your body would have used anyway during that time.
When the men walked their miles in 19 minutes at Syracuse, researchers found that they only burned 52 more calories than they would have had they been sitting on the couch during this time. On the other hand, the runners burned 105 net calories — twice as much — in the 9 ½ minutes it took them to run a mile.
If you look at the net effect over time, the results are even more pronounced. Walking for one hour burns 165 net calories, while running at just under 10 minutes per mile for this time uses four times as much energy: 660 net calories.
Please don't take this as an anti-walking message. Walking is good exercise, and it can help improve cardiovascular health. But if you're able to run, it burns far more calories.
Walking can still be an effective tool for weight control. You may just have to walk a little more (or faster or at an incline on a treadmill) to meet your goals.
Prescott, a physician and medical researcher, is president of the Oklahoma Medical Research Foundation. Cohen is a marathoner and OMRF's senior vice president and general counsel.