I had a partial tear of my right biceps tendon 27 years ago when I was 15, I cannot remember the percentage the doctor told me, but was not enough to warrant surgery. My right biceps is approximately 1” shorter than my left at full relax and has a much better “peak” at full flexion… IIRC I went about 8-12 weeks not doing a whole lot of upper body work when I tore it, and after that it was just a matter of easing back into things and understanding it was a ticking time bomb… however I did have a fairly successful career in powerlifting with several DL’s in the 600’s with zero issues, I just always made sure my right hand was an over hook rather than an under…