1) Tightness in your shoulders. This refers not just to the glenohumeral (shoulder) joint itself, but everything that connects to it, including the muscles in your upper arms, your chest, your upper back, and even your neck.
2) Weakness in your back. When you use the muscles in the front of your body too much, and the muscles in the back of your body not enough, this causes an imbalance. When the muscles in your back get weak, the muscles in the front are overworked when they have to complete a task.