I'm talking to you - yes you! Your posture sucks and your training isn't helping! Your shoulders slant forward, your head is hanging, and your thoracic spine is bent like an old man (or woman). You spend hours and hours each and every day sitting behind a desk or in a car and then plant your butt on a couch and binge-watch television shows. No wonder you look like something only halfway up the evolutionary ladder...
Several years ago Dan John mentioned that we need to do a lot more row-like movements to balance out all of the pushing movements we do in training. I distinctly remember him demonstrating the "Bat Wing" in a bar in Orlando, Florida... but that's a story for another time! Anyway, ask any guy how much he can Bench Press and you'll get a number. But ask them the same question when it comes to Rows and you'll get a blank stare.
Rows aren't sexy and they aren't going to make you look good naked - but they are going to keep you standing tall and allow you to move pain free. Recently we did a little experiment in our gym and took all pull ups out of the training regimen for about six weeks; this was completely voluntary, and if you wanted to do pull ups you were on your own to do so. Instead of pull ups we replaced all of the pulling movements with various types of ring rows, kettlebell rows and Renegade Rows. At the end of six weeks something interesting happened... everyone got better at pull ups without doing them. In my own situation my pull ups improved (no change in number or reps but range of motion and comfort increased) and I was able to do them without pain at the top and the bottom for this first time in several years.
So why should you do Rows instead of Pull Ups? First and foremost, most people who are training in a CrossFit gym have no business whatsoever doing Pull Ups. Using Bands, counterweights and kipping to get a Pull Up is just going to lead to problems down the road. Doing high repetition kipping or butterfly Pull Ups are going to cause problems for inexperienced athletes who don't have the requisite strength and depth of musculature to handle the rapid acceleration and deceleration the technique requires. Second, overemphasizing the overhead pull, without a balancing pull to the rear, is going to create imbalances in the chest, shoulders, biceps, upper back and neck. Adding tension to these areas is going to create dysfunction in any overhead pressing motions as well... just what you need! Finally, people who have compromised posture to begin with, which is most if not all of the athletes you are going to be working with, are just going to be reinforcing dysfunction by doing Pull Ups, especially high rep Pull Ups. They are starting off with poor thoracic stability and mobility, tight pecs and biceps, and poor head alignment... and they are going to end with more of the same.
So... how do you reverse what poor training protocols and bad posture are creating? I know this is going to be hard but... STOP DOING PULL UPS for a while. Seriously, stop completely and work on getting some strength in the Row. There are enough variations of Rows using Rings, the TRX or Jungle Gym, and Kettlebells to keep you busy for quite a while. Make sure that you are spending the time productively and not just blasting through the movement to get your reps in. Spend time locking down the ribs before pulling and working on getting as big of a range of motion as possible on each and every rep. It goes without saying that you should also look into how you can open up your pecs and biceps as well. There are a lot of things you can do with Kettlebells, Lacrosse ball and Foam Roller to improve the quality of these muscles and how they interact.
For more information on how to improve your posture be sure to check out Dr. Jon Rusin's article ("The Posture Cure") on the T-Nation website.