I tore my right biceps and it was the undergrip that did it. I have had a sore biceps for decades and when throwing things I would get sore near the elbow. I used to be a discus and javelin thrower. I cannot lock out my arms and never could. So there might have been some sort of damage already in the biceps. The heavy deadlift was the straw that broke the camel's back. What happened was the biceps doing the supination tore. So I cannot arm wrestle with my right arm or do supination with very heavy weight. My biceps get sore easily when training arms. I still managed to place second in the two recent Australian Grip Championships against all comers. I won some events, too, and still hold the record for best pinch grip ever with 92.5 kg with my right hand on my pinch grip machine.
I don't recommend that anyone do deadlifts as I consider it a dangerous exercise with little benefits for a physique. There are better exercises for traps and spinal erectors.
I had surgery done by a microsurgeon but 18 months after the injury and there was nothing they could do. The scar from the operation is almost invisible. I tore the sheath that covers the biceps, too. Had the tendon come off the bone I could have had it repaired. If the muscle tears there is little anyone can do about it. When I presented at the hospital when it tore they put my arm in a sling and sent me home! That was devastating. I can get my arms bigger but it is still painful to train biceps. I think I now prefer triceps training but also have very tender elbows from years of javelin throwing.
