In reply to dave frost: Well the one-armed chin-up is one of those goals that alot of people have. I started practicing them with a rope on the bar for my other hand,as each training session progressed I used the rope less and less untill eventually, ONE ARMER!!!
The problem that I think caused the injury is the initial explosive move from locked out arm to begin moving the body up. This is a very fast twitch movement and places alot of stress on the bicep tendon.
I was following an old training programme for chin-ups that was printed in Climber magazine a few years ago. This programme involved doing lock-offs etc as well as one-armers and various other chin-up exercises for around an hour. The strain placed on the muscles and tendons is obviously massive especially once you progress to the more advanced things like wieghted lock-offs.
I felt pain in the lower bicep area but just thought I'd pulled the muscle a little. Being a typical squaddie I just muttered to myself about stop being weak and cracked on. It was about 2 months before the pain became so bad training was just no longer an option,2 weeks before I went to Hueco Tanks!
Don't ignore pain!!! And probably leave one-armed chin-ups to the proffessionals lol.