as to the original question, there was a T-Nation article that was recently posted related to this
"Before I started I was well aware of the potential trauma this pull-up blitzkrieg could unleash upon my elbows. Most guys stop doing high frequency pull-ups because of an elbow injury. Sometimes the problem surfaces in the shoulder. In either case, the culprit is the same.
When you pull in the vertical plane your wrists naturally want to rotate. How much they rotate depends on your skeletal structure and soft tissue mobility. Regardless, your wrists never want to be locked in place for this exercise.
This is simple to verify. Work up to a three-rep pull-up maximum from rings and watch what your wrists do from the full hang as you train max strength ? they’ll never stay fully pronated on their own.
If the wrists can’t naturally rotate, the stress goes straight to the elbow, leading to pain and inflammation. Then the shoulder will join the pain party. If you observe shoulder movement when a guy does a pull-up from a fixed bar it looks the same as when he does it from rings.
However, there are small biomechanical changes when the wrists can’t rotate. You might not be able to see a difference, but you’ll eventually feel it when an underlying dysfunction rears its ugly head as shoulder pain.
Of course, many guys do pull-ups from a fixed bar every day, or every other day, and don’t have any problems. Most often it’s because their frequency is low enough to avoid it. With high frequency training, however, you’ve got to get everything right from the start. For pull-ups, this means allowing natural wrist rotation.
Now, if for some unforeseen reason you absolutely can’t get access to rings or TRX straps, the next best option is to do the high frequency pull-ups with a neutral, fat grip. The hammer grip is easiest on the elbows and fattening the grip takes more stress off them. However, you’ll still likely run into problems, even with a fat, neutral grip, if you do enough of them.
The absolute worst culprit is the chin-up from a fixed bar. Just hang from a bar with your palms supinated and you’ll immediately feel tension in your elbows. I’ve recommended the fixed bar chin-up for years, but things change. It’s completely out of all my current training programs because it locks the wrists in the most stressful position to the elbows.
Your body is just as valuable as any million-dollar athlete’s. I won’t let any athlete do pull-ups from a fixed bar, and I wouldn’t advise you to do it, either. The risk is not worth the potential reward. Use rings for pull-ups."