Y'all ever get in a physical altercation with some dudes that look like that? Those scrawny bastards can fight. They are made of muscle and rice and that's pretty much it.
My grandfather was 5'6" and built like that.
Born in 1918, had a bunch of brothers, grew up in the coal mines, WWII infantryman.
Fighting wasn't foreign to those coal miners, Pap was one who enjoyed a good scuffle.
I have no idea how so much strength could come from such scrawny arms.
Quite a few big guys figured out what you know, the hard way.