The number of rotator cuff injuries reported in the US is increasing, as are the number of surgical interventions for such injuries. These injuries can be debilitating and interfere with work and recreation. Healing can take a long time, and surgery is often required. These types of injuries take an enormous toll on physical and mental well-being. Rotator cuff injuries often start with impingement. Impingement is when the tendons of the rotator cuff muscle become inflamed or trapped beneath the shoulder blade, usually due to a poorly or inefficiently functioning shoulder joint. This can lead to pain, discomfort, tearing of the tendons, and more serious injury.
Looking at the underlying mechanisms of why these injuries occur can help us figure out ways to move our bodies that minimize the likelihood of injury. When in comes to rotator cuff injuries, the serratus anterior plays a surprising role in maintaining strength, stability and health of the shoulder girdle.
Anatomy
Serratus anterior is a muscle that connects the medial border of your scapula to your rib cage. It lies beneath the scapula (shoulder blade). It runs from the medial border of the scapula, under the scapula to insert on ribs 1-9. It is a stabilizer of the scapula that helps to keep this bone anchored to the rib cage during dynamic movement.
Serratus anterior holds the medial border of the scapula against the thorax. It also helps to laterally rotate the scapula as the arm is being lifted overhead. Other muscles contribute to both of these actions, so it is possible to move your arm in this way without fully engaging the serratus anterior muscle. But this is one of the causes of shoulder dysfunction that can lead to chronic injury.
[By Anatomography - en:Anatomography (setting page of this image), CC BY-SA 2.1 jp, https://commons.wikimedia.org/w/index.php?curid=22208655]
Function
The serratus anterior It functions to protract the scapula and rotate the scapula upwards when you reach your arms overhead. It works in tandem with the trapezius muscle, which is the large, diamond shaped muscle of the upper back. Most of us have imbalanced use of our trapezius muscle - the upper fibers do most or all of the work, while the lower fibers, along with the serratus anterior, are largely unused. This creates imbalance in the muscular complex that is responsible for shoulder movement. When we use the upper trapezius almost exclusively, the shoulder blades lift when the arms lift, which can cause compression of the rotator cuff tendons.
On the other hand, if we engage serratus anterior and the lower trapezius when the arms lift, then the shoulder blade still rotates effectively, but is also stays anchored onto the back of the rib cage, which allows for more space between the scapula, clavicle, and humerus, minimizing the risk for impingement.
Individuals who suffer from rotator cuff impingement show reduced recruitment of the serratus anterior while lifting their arms overhead. Conversely, when the serratus anterior is actively used, it helps to prevent impingement of the rotator cuff muscles, keeping the shoulder girdle stable and strong through a range of activities.
Strengthening the serratus anterior can promote balanced lifting of the arms overhead without overuse of trapezius.
Serratus anterior in yoga
The serratus anterior is the unsung muscular hero of your yoga practice. It is instrumental to so many poses - downward dog, plank, chaturanga, crow, side plank, handstand and many more arm balances. A properly functioning serratus anterior can assist you and move you forward in your physical asana practice. An improperly functioning serratus anterior can cause injury. So let’s look at ways we can strengthen this muscle and some cues to make sure that we’re using it properly throughout our yoga practice.
Table top serratus push ups
Come into table top position with your hands slightly in front of your shoulders. For added challenge, have a friend place a 10lb sandbag on your upper back. Keeping your elbows straight, sink your chest towards the floor and feel your shoulder blades begin to come together across your back. This represents a totally relaxed (unengaged) serratus anterior muscle. Now press firmly into the floor, lifting your chest and raising your upper back towards the ceiling. In this position, the shoulder blades begin to move around towards the sides of your rib cage and serratus anterior is engaged. Repeat this action 10-20x then rest.
Table top position to prep for serratus push-ups. Keep the elbows straight as you sink through the upper back. Then press firmly into the ground to lift and round through the upper back, engaging the serratus anterior.
Plank pose
From your table position, extend both legs behind you with your knees lifted off the floor. Your hands should still be slightly in front of your shoulders. Press your arms firmly into the floor and find a lift of the upper back. Try to hold this pose for up to one minute. If you notice that your upper back begins to fatigue and you are collapsing the upper back, then come out of the pose.
Plank pose. Try to maintain the integrity of your plank pose, not letting your shoulder blades wing out, a symptom of a disengaged serratus anterior.
Warrior 1 (or any arms overhead pose)
In Warrior 1, the arms are lifted up overhead. The serratus anterior muscle contributes to this action. When you practice this pose and others like it, make sure to pay attention to how you are lifting your arms and what your alignment is like once you are there. When you are lifting your arms, externally rotate them at the shoulder. Lift slowly. When the arms are in position, make sure you don’t feel any pinching at the shoulders. Engage the muscles of your middle and upper back and think about lifting your chest. Lengthen through your sides and your center line. Breathe here.
In Warrior 1, try to draw the keep the inner border of your shoulder blades hugging your rib cage, and keep the bottom tips of the shoulder blades down. This helps to train proper functioning of the serratus anterior.
Downward dog
Proper alignment in downward dog is key to healthy shoulder mechanics. In your downward dog, make sure that your hands are placed at least shoulder width distance apart, maybe even wider. The index finger should be pointing forward and the fingers spread. Keep your elbows straight and your shoulder blades wrapping around the sides of your body. If you have a lot of mobility in your shoulders and upper back, resist the urge to sink your chest or place your head on the floor. Try to stay fully engaged in your serratus anterior. Tilt your pelvis forward so that your sits bones point towards the ceiling and there isn’t undue pressure on the lower back. Breathe, and try to maintain the pose for 2-4 minutes.
Downward facing dog pose. This is a good pose to practice engaging the serratus anterior while carrying some weight in the upper limb. Keep your arms lengthening away from the body, as the shoulder blades hug in towards the back.
Crow
The last pose on our list is crow pose, which is a fairly advanced arm balancing pose. Not everyone is going to be able to do this pose because it requires not just balance, but flexibility through the hips, and good upper body strength. If you can safely practice crow, use this pose as an opportunity to notice the way your hands press into the floor. Try to engage through your back to find lift, rather than letting gravity pull the body towards the earth. If you have difficulty balancing, try the supported version shown below with blocks stacked under the forehead.
Crow pose is a great way to integrate all the previous exercises into a true test for the serratus anterior. Notice the rounding of the upper back, which means that serratus anterior is engaging on both sides to draw the shoulder blades away from one another.
These poses represent just a small sampling of ways to strengthen the serratus anterior. They have the advantage of using primarily body weight and not requiring any special equipment. If you are suffering from rotator cuff impingement, try these poses and see if you notice any reduction in your pain.