What is scapula winging?
The scapula is the anatomical term for the shoulder blade. Scapula winging describes the position of the shoulder blade sticking outwards as opposed to being flat against the ribcage. A winging scapula that is left untreated can lead to more debilitating shoulder injury like a rotator cuff tear. Doing scapula push ups will exercise the muscles that prevent scapula winging.
The normal biomechanical position of the shoulder blade should always be rested flat against the ribcage regardless of the position of the arm. The shoulder blade slides upwards, downwards, forwards, backwards as well as rotating clockwise or anti-clockwise as the arm moves, but it should not come away from the ribcage as seen in the right shoulder blade in the picture below.
The following video shows how a winging scapula looks like when the shoulder is moving. Look at how much the bottom tip of the left scapula sticks out compared to the right (normal) scapula.
Scapula instability causes shoulder injuries
It is important that the above mechanics occur as the stability of the scapular is an essential facet to the proper function of the shoulder complex. An analogy would be a bicycle. There are many parts that are put together to allow the bicycle to move as it is pedaled. If the chain of the bicycle is loose, not only it creates noise but it also the cyclist will have to pedal harder to reach the same speed, making it inefficient. Eventually other parts will be worn out faster than normal. Similarly, if the muscle that holds the shoulder blade against the ribcage does not work properly, causing scapular winging, inappropriate activation from other muscle groups will compensate resulting in overuse and pain in these muscles. This will lead to a cycle of pain in the muscles and poor biomechanics in the shoulder, subsequently leading to problems such as shoulder muscle (rotator cuff) impingements or tears.
Serratus Anterior Muscle
The primary muscle that stabilizes the scapula to the ribcage is the Serratus Anterior. Other muscles that offer support to that role are the middle and lower trapezius. Hence any weaknesses in these muscles due to injury, disease process or lesion in the nerve supply can result in winging. In cases where the nerve supply is intact, specific exercises targeting at the Serratus Anterior and middle and lower trapezius can be performed to rehabilitate the specific muscles affected.
Shoulder push-ups is a good way to train the serratus anterior muscles. The idea is to push your chest away and towards the ground by moving your shoulders and not from the elbows. This exercise is demonstrated in the video below. An easier way to perform this exercise is to lean against the wall with your hands instead of on the floor.