Brian R on Treadmills

Well I'm finally lured into posting after several years. This question about treadmill physics comes up periodically. When it does the (quite innocent) propagation of misinformation kicks in. I can provide the answer. Note that RayK is likely to disagree with me. He's a far more accomplished athlete. I am the trained physicist (PhD in optical physics to be exact).

When you run up a hill on the road, you do work (use energy) against gravity to increase your potential energy. This work is not efficient, so you generate a lot of heat in your muscles as well. When you run on an incline on the treadmill, you do work on the treadmill motor to create heat (instead of going up a hill and attaining potential energy). Again it's not efficient, so you again get hot and sweat. (A clever scheme would be to recover some of the work you're doing on the treadmill to charge a battery or supply electrons to the grid.)

When you run downhill on the road, gravity is working on you, expending the potential energy and you are ultimately dissipating that energy as heat in your leg muscles. When you run downhill on the treadmill, the treadmill motor is working on you (but not efficiently so it's also getting hot) and you are dissipating that work as heat mostly in your leg muscles (instead of allowing the treadmill to impart potential energy by lifting you up higher and higher).

This partly explains why the gentleman takes the cover off his mill to let it cool.

Both scenarios rely on your ability to apply force via friction between shoe and running surface. Take that away and you face plant.

The important message, important enough to post, is that *hill running on a treadmill is "equivalent" to hill running on roads*--up to the caveats that there is usually no appreciable wind on the treadmill and the treadmill surface is more compliant than the road surface. You can't directly set the pace on the treadmill by adjustment of your effort, so the psychology is somewhat different of course.

Qualified, polite criticism always welcome.