I was talking to a friend of mine, who works out at a commercial gym and does freeweights and cables and stuff and doesn't train pullups often, and he mentioned casually that he can do a one-arm chinup (hand supinated). I was surprised, and made sure that he and I were thinking of the same exercise. He didn't show it to me, but from what he described he is really talking about a one-arm chinup (one hand free, the other doing the pulling). He said he did it as a warmup. Then he proceeded to say that a lot of people at his gym can actually do one-arm chinups and such. I don't know what their training is like, but if they go to a commercial gym regularly I'm assuming it's not really focused on GST. Do you think it's possible (probable?) to get a one-arm chinup without focusing too much on GST, rather training mostly freeweights? PS. My friend weighs almost 90kg, making it seem crazy to me.