Here's an interesting question we received this month from a reader:
DEAR DR. PRESCOTT: I have been a runner for 50 years. In your last column, you told why running a mile was more exercise than walking one. Makes sense to me! However, as I approach becoming an octogenarian, my times have slowed dramatically. Where I once could not have conceived of being unable to run a 10-minute mile, even such “slow” times are no longer possible. Running a mile now takes me about 17 minutes, while walking the same distance requires 30 seconds to one minute more. I usually walk or run about four miles three times a week. However, I notice that my legs are more tired after running. Do you think that with my speeds being so similar, walking for me is as good as running?
Dr. Prescott prescribes
Our last column discussed why running typically burned more calories than walking the same distance. But I never said that running was a “better” exercise.
The low-impact nature of walking does not require a person to make a small jump with each step. Rather, in walking, at least one foot remains on the ground at all times. Thus, it does not entail an explosive push upward against gravity, a forceful motion that can strain things such as Achilles and hamstrings. Nor does it require a series of shock-absorbing landings, whose impacts over time can exert a heavy price on your knees and hips.
This likely explains why you find that your legs feel peppier after a walk than a run. But do they also feel fresher because you're doing less work?
I doubt it. The research studies that have examined the relative caloric burn of walking versus running have found that the differences are based primarily on pace, not the inherent “difficulty” of one form or locomotion versus the other. Indeed, when researchers compared walkers who were covering their distances at a rate of 10 minutes and 30 seconds per mile — an extremely fast walking pace — they found that they actually burned more calories than subjects who were running at the same speed.