it can be done, you just don't like the flavour we want to give it of them just being that strong, you're too caught up in 'but a regular earth human couldn't do that' to just let it happen, these aren't regular earth humans who are doing these things, not even including the ones who just plain aren't human, regular humans can't use magic or ki or channel the spirits of nature or their ancestors to resist damage in a battlerage.
the people of the world is infused with a natural magic, some use it to cast spells, others use it to surpass their physical limits.