Originally Posted by
Maybach
The weight is being supported on the back, but the hands prevent the weight from moving, and they do that by exerting force. If the hands had no role to play, then why not just unrack the back with no hands? The hands should not, in any case, be entering force pressing the bar INTO your back: the weight will do that itself quite handily.
Your grip is causing you bicep pain in perhaps the most classic way possible. I assure you, you can fix your grip if you try harder.