Well, I will ask again. If it is the vibration and shock, why is it impossible to develop tennis elbow if you hit forehands only? ie no backhand, no use of the outer/extensor side of the elbow.
I'm not looking to shoot your ideas down. I think you're right - technique flaws are a fundamental issue when we get into the whole ball-o-wax that is arm ailments and injuries among tennis players. But I'm of the mindset that nobody has perfect technique, including the killers on TV who compete to earn their lunch money. The pros do employ significantly better technique than mere mortals like ourselves more often for sure. So that helps with reducing wear and tear on the soft tissues in their arms despite the fact that they play all the time.
I'm mending some real-deal tennis elbow right now and this is the first arm ailment I've had in all my tennis years - I'm a month away from birthday #52. My technique certainly doesn't flirt with perfection, but I've stayed plenty healthy through the years despite a very busy schedule of playing, teaching, and coaching. I had a workout with one of the guys I coached in high school who now plays on a small college team and when I woke up the next day, I knew that I had a significant issue going on.
Not a case of tennis elbow so acute that I couldn't hold a glass of water, but it was MIGHTY uncomfortable on several days when my arm was particularly grumpy over the next couple of weeks. I've played a few times since this onset and I can honestly say that hitting one-handed backhands and serves at full speed were no problem. The real
whoa Nellie pain came along when I caught an occasional forehand a little late. Bad technique. But I have to assume that it was my forehand technique that initially did it, since that's exactly what aggravated it when I did it again - no other shot.
What changed? I was playing with the same super arm-friendly Volkl C10's that I've enjoyed for years, I wasn't hitting with my pal after an exhausting day on the courts, and I was at the end of my coaching season with the high school kids, so I certainly wasn't rusty. I sampled a full bed of poly (fresh poly tensioned at 43 lbs.) and didn't even use it for the entire workout. So it's my own dang fault for tap dancing in a minefield - I knew better and tried it anyway thinking I could proceed with caution.
Bad technique is a fundamental stressor for any player's arm, but I'm sure that certain equipment can function as a more effective transmitter of impact shock. Equipment is absolutely a contributor to arm troubles in at least some cases. That being said, I don't think it's realistic to try and boil down the root cause of every arm injury to just one thing. That's why we get into these discussions - fine by me considering how ferociously cold it's turned out there for the time being. Can't even ride my bike on the trak-stand in the garage. This is what the surfers call "burrr-ito!!"
As a tennis coach/teacher, I can't just say that it's okay to play with a soft racquet and string combo, but then go out there and take violent swipes at the ball all day trying to emulate your favorite pro. But I've also seen a lot more than just one or two cases among the locals in my area where players both young and older have run into injuries shortly after switching into harsher equipment including poly strings. And some of those cases included higher level players. Folks who have me string their racquets never get to switch from a softer string into a poly setup without first talking it over.
Every injury brings a very unique set of circumstances, so I think it's impossible to boil all of them down to one common denominator. But decent technique AND cozy gear are both among the highest priorities for everybody.