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Medical The effort of walking downhill

  1. Dec 3, 2008 #1
    Which burns more calories: walking on a level sidewalk for an hour, or walking
    down a sidewalk of slope 10 degrees for an hour?
     
  2. jcsd
  3. Dec 3, 2008 #2
    Downhill, right? I would think it would consume the same calories as walking on a level sidewalk plus whatever muscular effort is necessary to lower your body down the slope slowly.

    I was once on the 29th floor of a skyscraper when there was a power outage that killed the elevators, so everybody who was in the building (it was 9:00 at night, I was working late, so fortunately there were only a handful of people in the building) had to leave via the stairs. By the time I got to the bottom I practically felt crippled. It would be more effort to climb 29 flights of stairs, of course, but going down was nothing to shake a stick at either.
     
  4. Dec 3, 2008 #3
    i think it would be less, but feel like more because of the use of muscle unaccustomed to the task. but it's probably also a function of velocity, and there may be an optimum speed to minimize the energy lost. if that optimum is a running speed, then it complicates the problem. fwiw, there is a speed where walking becomes much less efficient that running, and this is about where you will naturally break into a jog. when going downhill, i'll break into a jog easier, but i don't know how different the speed is.
     
  5. Dec 3, 2008 #4
    Loren is being tricky there, I think: noticed that he specified walking and asked in terms of duration rather than distance.

    I think that, as you mentioned "there is a speed where walking becomes much less efficient that running" is the key. I think the reason for this is that due to the mechanics of walking, you're actually applying some force to prevent your body from descending too fast. Switching to jogging makes it so that you're expending less energy doing that; that's why it's more comfortable at a certain point.

    Obviously if you were on roller blades or something it would definitely take less effort to go downhill. But I think that the mechanics of walking make the outcome different in that case. That's my theory, anyways. I bet there's a relationship between the length of a person's legs and exactly what the speed is on a given incline where jogging becomes more comfortable than walking.
     
  6. Dec 4, 2008 #5

    jim mcnamara

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    If you assume the mechanics of standing upright and maintaining balance are the same for both situations in terms of energy expenditure then:
    1. going downhill you expend energy to resist acceleration (dissipating potential energy) which is not required for walking on a level surface
    2. The energy required to move horizontally will be the same, except that the downhill person walk tranverses less horizontal distance.

    I have no idea what actual numbers to plug in for this but I can't find a biophysics site, so this is from an exercise physiology site which is not quite what is needed.
    http://www.wv-hsta.org/CDC_CHC/walking_kcal_expenditure.htm See the section on stairs.
     
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