The answer to that question may seem obvious if you look at it from a time standpoint: it's much exerting and tiring to run for ten minutes than to walk for ten minutes. However, if you think of it from a distance perspective, the question is harder than you think. You could walk five miles in ninety minutes, or run five miles in thirty minutes. Sure it's more tiring running, but you're exercising for three times longer if you walk. Now it doesn't seem like a straight forward question does it?

Jumping to the conclusion: You burn more calories running the same distance than walking, but the speed at which you run doesn't matter as much unless you run very fast.

Here is the plot comparing calories consumed walking and running at different speed (click to enlarge):

191 pounds is the average male weight ages 20-74 years, and 164 pounds is the average female weight ages 20-74 years in the US (source). The calorie consumption per minute for each of the running and walker speeds were taken off the Healthstatus.com website (I entered 100 minutes for each activity then divided to get the extra significant digits).

As you can see, you spend more calories running the same distance than walking, but there is no clean correlation between speed and calories spent. In fact, you spend less calories if you walk briskly or too slowly than if you walk at a normal speed. On the other hand, you spend more calories running slowly or running very fast.

The above comparison falls short, however, since each exercise takes different lengths of time. Since the human body consumes calories while resting (or even sleeping), in the above comparison the runners are not given the benefit of finishing early and burning calories after the exercise.

For the following graph, I set the total time to be 150 minutes (how long it takes to walk five miles at 2 mph) and added the resting caloric consumption for exercises that don't take as long (I chose "reading" off the Healthstatus website since resting wasn't available).


As you can see the benefits of running is now further exemplified by adding the extra resting calorie consumption. Nevertheless, there still isn't much benefit in running fast, unless you run very fast. Of course this completely ignores the benefits of extra time which enables you to do things like lifts weights or blog.

In conclusion, lessons learned from this number crunching exercise:

1. Run if you can, you burn more calories than walking the same distance.
2. Don't worry about running fast, unless you run very fast or you want the extra time for something else.
3. Fast walking is counter-intuitively unproductive. Try to step it up to a light jog.

If you want to play around with this more or just want to double check my numbers, here is the Excel spreadsheet I used to create these charts.

Labels: exercise, health, random calculations