I admit that I am one of those annoying people who taps his leg up and down a lot when sitting. Earlier today, this came up in a conversation with a friend and she said that people typically do this at the leg’s resonance frequency, and thus the tapping motion actually uses very little energy. I’d always thought this was just my body’s fidgety way of burning off a little bit of energy, but this would indicate that such is not the case. I now notice that it seems a lot more difficult to tap my leg at anything but my usual frequency, but that just may be force of habit.
I know very little about resonance frequencies aside from basic movie logic, so if someone could enlighten me a bit on this I would appreciate it.