I have always been physically hard on myself like others on this thread.
Both my biceps are torn at the elbow although I never had surgery to restore them to their original shape because they were only partially torn.
I tore the right arm first at an armwrestling competition 38 years ago. It wasn't too bad and I didn't know any better so I just let it heal. It looks slightly shorter and I did lose a little strength because of the change in leverage I believe.
Then I tore my left bicep about 15 years ago pulling/launching a wooden boat stuck on a gravel beach while I was guiding at caribou camp. That was a little worse and like the first one, the shape and strength changed a little. However, considering that it was fully functional, the orthopaedic surgeons were not very enthusiastic to repair it.
But, while in heavy training in 1985 I completely tore my major pectoral tendon off the bone - they fixed that immediately.
I believe the problem is genetic since strength runs in the family and the surgeon that operated me said that I had tendons like large steel cables... in the case of my pec, the tendon didn't rupture, it puled off the bone... with my biceps, the actual muscle fibre is what tore.
Both my mother (lifting a big rock out of her garden) and my brother (carrying a dirt bike motocycle on his shoulder) pulled tendons off the bone or tore muscles.
Today the injuries I discussed are absolutely fine and at 63 I comfortably shoot a 75 # longbow.