Physical feminism is the idea that women should 'empower themselves' through developing physical strength, endurance, etc...kinda reclaiming their bodies as functional rather than just aesthetic.
Myself, I think everyone should. Gender isn't relevant. You aren't free if you can't go for a 5 mile walk without half dying, climb up wire mesh by yourself, etc. Ok, I don't literally mean you should be able to do exactly those things. But your body should be useful to you. Not something that holds you back. You should own your skin, muscle and bone. Not be held back by it.
And certain low-IQ rabies sufferers take this idea too far.