The most common, and easily correctable mechanical deficit occurs when the elbow moves too far from the wall, or raises too high during a Gaston. This simple aberrant motion disengages the core, and puts a lot of stress on the shoulder stabilizers. You can see that in this picture. The right shoulder is close to the wall which pushes the left shoulder away – actually shortening her reach. The right elbow is drifting away from the wall, and her hips drift right – all putting extra stress on the right shoulder. If she were to pull her right elbow down and almost rest it on the wall, she would be able to rock up and over her left foot. It’s all about moving your body on the wall, not pulling yourself up the wall.
Doing this: pulling the elbow straight down from the hold, and pulling the bottom corner of your scapula up toward your elbow – you should feel your chest lift up, essentially pushing yourself into a mini front-lever. You’ll feel your core engage, and your feet push down into the holds.