[Paleopsych] Runner's World: How Many Calories Are You Really Burning?

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How Many Calories Are You Really Burning?
http://www.runnersworld.com/article/printer_friendly/0,5046,s6-197-0-0-8402,00.html

    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
    landing.
    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
    walking.

    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
    obesity.
    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
    than running.
    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
    Running
    .75 x your weight (in lbs.)
    .63 x your weight
    Walking
    .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.