Is there any point on setting an incline on a treadmill?

[Tyro]

Since the runner's level does not actually change, they are not doing any work against gravity. Their total output wattage -- if it can be measured -- should be the same regardless of inclination.

Yet, running on an inclined treadmill seems more difficult. Is the difference purely in the runner's head, physiological (muscles work less efficiently at that configuration) or am I missing a physical reason why the runner actually does more work?

 

[Tyger]

I'm going to make a guess

based on common sense. That people can put out more work when they're walking uphill therefore the treadmill can be set to a higher force level. When they're on a level platform they have to use their arms to limit their motion, on the "hill" they have their body weight too.

 

[KillaMarcilla]

I believe that the trick here is that you're doing work on the treadmill since your feet are pushing down on it, they're moving along, and work is a force through a distance

Or maybe you could look at it like it's the same as walking up a stationary hill, relatively

Maybe I don't know what I'm talking about, though

 

[Hurkyl]

I see several factors at work here.

First, the work our bodies do is not entirely transmitted to the outside environment. Energy is expended doing work on our bodies in order to generate a force! For example, pushing on a wall is a lot harder than leaning against it.

Secondly, our bodies are not stationary as we walk on a treadmill; at the very least, we are moving one leg forward at all times. If we're on an incline, then we have to do (more) work against gravity to move our leg up the incline.

Also, I imagine our bodies are optimized for travel over level surfaces, so we probably waste extra energy when walking an incline.

 

[HallsofIvy]

If the treadmill is on a tilt, then every time you take a step forward, you lift your body upward and so do more work than if it were level. Of course, you don't go upward because the treadmill then moves you back downward but you don't "regain" the work you have done. If you walk up a flight of stairs and then take an elevator back down, you have still done the work of walking up stairs!

 

[LURCH]

Originally posted by HallsofIvy
If the treadmill is on a tilt, then every time you take a step forward, you lift your body upward and so do more work than if it were level. Of course, you don't go upward because the treadmill then moves you back downward but you don't "regain" the work you have done. If you walk up a flight of stairs and then take an elevator back down, you have still done the work of walking up stairs!

This is exactly correct. Consider the fact that if you stand still on a horizontal treadmill, you will remain stationary. Do the same on an inclined treadmill, and you will roll off the back end. Extra work is required from you to counteract the effect of gravity trying to move you downward and, therefore, rearward. The steeper the incline, the more rapidly an inactive person would roll off, therefore the more work must be done to counteract this effect.