system
Given the following post, respond as if you're commenting on Reddit:
human
Why does running on an inclined treadmill feel like running up a hill (needs more energy) even though you're not gaining elevation (potential energy)?

If you run up a hill, you have to work harder and that work (energy) is transferred into potential energy because at the end you are higher in elevation then when you began.

Running on an inclined treadmill feels like running up hill, and seems to require the same increase in energy but without the extra potential energy at the end.

Where does that extra energy go?
gpt
You still gain potential energy by stepping forward on an inclined treadmill, but you lose the energy as soon as the treadmill pulls you back down again. The extra potential energy is transfered to the treadmill belt, where it becomes kinetic energy (and consequently, the treadmill motor has to provide slightly less work to drive the belt).