(alot of people still get elbow problems..even when going behind the head)
I've had unusual injuries that i haven't seen mentioned much, by using the most highly effective exercises that target the muscles better. The irony of very effective exercises is that they hit the belly of the muscle better than most exercises, which essentially means no joint problems.
The downside: the muscle itself is subject to higher stresses, which can result in muscle fiber tears. Takes anywhere from 2 to 8 weeks approx. to recover from, from experience. I've had this happen with lats, tris and bis using specific, more effective exercises over the last few years. The essential issue is that the same intensity that makes the muscle work harder also leaves it open to inordinate stress it's not used to and can't handle.
Anyone with pain from extensions or any exercise should after healing up sample many variations before giving up on the exercise-seated ext., incline, decline ext., etc. in order to find those that are good but also don't cause injury. Since i can't do lying extensions any more due to muscle fiber tears I've found that bent-over pulley extensions do the job on the muscle, without causing any injury-each exercises uses different angles and leverage of course. Only thru trial and error of variations can one find what not only works but that doesn't cause chronic injury.
Besides finding alternatives the other thing of course is to raise the intensity in ways that do not involve heavier poundages with low reps - keep the reps high, keep the rest times low or lower them further, superset, etc.
