The chest consists of the pectoralis major and pectoralis minor muscles, which spread across the front of the ribs and attach to the shoulder blade and sternum. These muscles are important during respiration and shoulder and arm movements. When tight or restricted, they can contribute to the forward, rounding position of the shoulders. This can also contribute to or be the result of weakness in the back of the shoulder blades or upper back area. Sustained forward body positions such as computer use or sitting with bad posture can lead to postural deficits that make the spine more vulnerable to compression fractures in people with low bone density.
For a strong chest, shoulders and back, it is important to make sure that you address these muscles with strengthening. However, it is also important to take time to relieve tension and tightness that can develop in these muscles by stretching to allow for a more upright posture and better length-tension relationships of the posterior shoulder and upper back musculature.