# Exertion from swinging on a playground swing

I've read about how by tilting one's body one changes one's center of mass while swinging on a playground swing, and thereby increases the energy of the swing.

But I would like to get a better sense of why one can get into a swing of ~1.5 meters above the ground on the back and front peaks of the swing (elevating an adult body weight that height each time), and do that repeatedly for, say, 10 minutes, and yet not at all feel fatigued--whereas if you were trying to jump up from the ground to that height you would be fatigued after just a few jumps.

I get the sense that the answer is related to the idea that you are "loading" the swing gradually with potential energy on each swing, and that each iteration of that requires only a little effort, but I'm still sort of surprised at how much sustained energy you can generate with so little feeling of exertion (it feels like one can keep swinging high with little effort for an hour, easily), and I thought there might be some subtleties to this that I don't understand.

Now, starting from rest at the bottom of this idealized swing, you would indeed need to do a bit of pumping to get started on your own. But you would only need to exert an amount of energy equal to your maximum change in potential energy desired (i.e., roughly $mgh$), and you would only need to exert this amount of energy once (well, a little at a time until you reach your desired height, but you wouldn't have to keep exerting this amount of energy each period).