squat form

Hi, When I squat the bar doesn't grip my back as well as I want it. The bar feels slippery on certain shirts I wear. When I bench, my shirt makes my set-up feel less stable as well due to the slipping. Has anyone else experienced this? Aside from chalking the back of my shirt, are there any...

Stopped by the orthopedists to have a look at an old right ankle injury that limits motion. He said it some arthritis and that the only option would be fusing it if the pain gets too much, which I'm not interested in. I've never irritated it in the gym, ever, and have done 1000 lbs. on leg sled...