I have an injury that deformed my bicep for life. Please be careful when you do preacher curls. I did something totally rookie. I was on my fifth set of standing preacher curls. First mistake, I usually stop at 4 sets. I decided to try and max out 5 lbs higher than my max, and on the second reps, the tendon that attaches the posterior bicep snapped off of my deltoid. Talk about pain. I ended up with black and blue bruises on both side of my bicep within 2 days. Now, my bicep hangs down because it's detached for one of the heads. I tried to get it fixed by 3 specialists in Boston, but no-one would do it. As a result, I can never compete, due to the lack of symmetry in my arm. When I flex, it's a very high peak, but it looks like part of the bicep is missing. My strength is only slightly weaker now that it's recovered. The only real problem is my vanity gets in the way. Unflexed it looks the same as the other one. Hope this helps someone.