[Paleopsych] Runner's World: How Many Calories Are You Really Burning?
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Thu Sep 8 22:01:39 UTC 2005
How Many Calories Are You Really Burning?
If you think running and walking both torch the same number of
calories per mile, you better put down that cookie
by: Amby Burfoot
A few months ago I got into an argument with someone who's far smarter
than I am. I should have known better, but you know how these things
go. Needless to say, I lost the argument. Still, I learned something
important in the process.
David Swain is a bicyclist who likes to ride across the country every
couple of years. Since I spend most of my time on my feet, I figured I
could teach him something about walking and running. Perhaps I should
have paid more attention to Swain's Ph.D. in exercise physiology, his
position as director of the Wellness Institute and Research Center at
Old Dominion University, and his work on the "Metabolic Calculations"
appendix to the American College of Sports Medicine's Guidelines for
Exercise Testing and Prescription.
Both Swain and I are interested in the fitness-health connection,
which makes walking and running great subjects for discussion. To put
it simply, they are far and away the leading forms of human movement.
Every able-bodied human learns how to walk and run without any
particular instruction. The same cannot be said of activities such as
swimming, bicycling, skateboarding, and hitting a 3-iron. This is why
walking and running are the best ways to get in shape, burn extra
calories, and improve your health.
Our argument began when I told Swain that both walking and running
burn the same number of calories per mile. I was absolutely certain of
this fact for two unassailable reasons: (1) I had read it a billion
times; and (2) I had repeated it a billion times. Most runners have
heard that running burns about 100 calories a mile. And since walking
a mile requires you to move the same body weight over the same
distance, walking should also burn about 100 calories a mile. Sir
Isaac Newton said so.
Swain was unimpressed by my junior-high physics. "When you perform a
continuous exercise, you burn five calories for every liter of oxygen
you consume," he said. "And running in general consumes a lot more
oxygen than walking."
What the Numbers Show
I was still gathering my resources for a retort when a new article
crossed my desk, and changed my cosmos. In "Energy Expenditure of
Walking and Running," published last December in Medicine & Science in
Sports & Exercise, a group of Syracuse University researchers measured
the actual calorie burn of 12 men and 12 women while running and
walking 1,600 meters (roughly a mile) on a treadmill. Result: The men
burned an average of 124 calories while running, and just 88 while
walking; the women burned 105 and 74. (The men burned more than the
women because they weighed more.)
Swain was right! The investigators at Syracuse didn't explain why
their results differed from a simplistic interpretation of Newton's
Laws of Motion, but I figured it out with help from Swain and Ray
Moss, Ph.D., of Furman University. Running and walking aren't as
comparable as I had imagined. When you walk, you keep your legs mostly
straight, and your center of gravity rides along fairly smoothly on
top of your legs. In running, we actually jump from one foot to the
other. Each jump raises our center of gravity when we take off, and
lowers it when we land, since we bend the knee to absorb the shock.
This continual rise and fall of our weight requires a tremendous
amount of Newtonian force (fighting gravity) on both takeoff and
Now that you understand why running burns 50 percent more calories per
mile than walking, I hate to tell you that it's a mostly useless
number. Sorry. We mislead ourselves when we talk about the total
calorie burn (TCB) of exercise rather than the net calorie burn (NCB).
To figure the NCB of any activity, you must subtract the resting
metabolic calories your body would have burned, during the time of the
workout, even if you had never gotten off the sofa.
You rarely hear anyone talk about the NCB of workouts, because this is
America, dammit, and we like our numbers big and bold. Subtraction is
not a popular activity. Certainly not among the infomercial hucksters
and weight-loss gurus who want to promote exercise schemes. "It's
bizarre that you hear so much about the gross calorie burn instead of
the net," says Swain. "It could keep people from realizing why they're
having such a hard time losing weight."
Thanks to the Syracuse researchers, we now know the relative NCB of
running a mile in 9:30 versus walking the same mile in 19:00. Their
male subjects burned 105 calories running, 52 walking; the women, 91
and 43. That is, running burns twice as many net calories per mile as
walking. And since you can run two miles in the time it takes to walk
one mile, running burns four times as many net calories per hour as
Run Slow or Walk Fast?
I didn't come here to bash walking, however. Walking is an excellent
form of exercise that builds aerobic fitness, strengthens bones, and
burns lots of calories. A study released in early 2004 showed that the
Amish take about six times as many steps per day as adults in most
American communities, and have about 87-percent lower rates of
In fact, I had read years ago that fast walking burns more calories
than running at the same speed. Now was the time to test this
hypothesis. Wearing a heart-rate monitor, I ran on a treadmill for two
minutes at 3.0 mph (20 minutes per mile), and at 3.5, 4.0, 4.5, 5.0,
and 5.5 mph (10:55 per mile). After a 10-minute rest to allow my heart
rate to return to normal, I repeated the same thing walking. Here's my
running vs. walking heart rate at the end of each two-minute stint:
3.0 (99/81), 3.5 (104/85), 4.0 (109/94), 4.5 (114/107), 5.0 (120/126),
5.5 (122/145). My conclusion: Running is harder than walking at paces
slower than 12-minutes-per-mile. At faster paces, walking is harder
How to explain this? It's not easy, except to say that walking at very
fast speeds forces your body to move in ways it wasn't designed to
move. This creates a great deal of internal "friction" and
inefficiency, which boosts heart rate, oxygen consumption, and calorie
burn. So, as Jon Stewart might say, "Walking fast...good. Walking
slow...uh, not so much."
The bottom line: Running is a phenomenal calorie-burning exercise. In
public-health terms--that is, in the fight against obesity--it's even
more important that running is a low-cost, easy-to-do, year-round
activity. Walking doesn't burn as many calories, but it remains a
terrific exercise. As David Swain says, "The new research doesn't mean
that walking burns any fewer calories than it used to. It just means
that walkers might have to walk a little more, or eat a little less,
to hit their weight goal."
What's the Burn? A Calorie Calculator
You can use the formulas below to determine your calorie-burn while
running and walking. The "Net Calorie Burn" measures calories burned,
minus basal metabolism. Scientists consider this the best way to
evaluate the actual calorie-burn of any exercise. The walking formulas
apply to speeds of 3 to 4 mph. At 5 mph and faster, walking burns more
calories than running.
Your Total Calorie Burn/Mile
Your Net Calorie Burn/Mile
.75 x your weight (in lbs.)
.63 x your weight
.53 x your weight
.30 x your weight
Adapted from "Energy Expenditure of Walking and Running," Medicine &
Science in Sport & Exercise, Cameron et al, Dec. 2004.
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