We identify it as periscapular due to the fact that the muscles we are talking about do not in fact lie on the scapulae, or shoulder blade, they act upon it. In our last post we discussed the internal and external rotators of the shoulder; some of those muscles rest on the scapulae but perform extrinsic work on the arm instead of moving the scapulae. Periscapular muscles work to stabilize and move the scapulae on the rib cage. These muscles have 3 actions within each swim stroke.
Stability
Force Generation
Range of Motion
Stability
During any swim stroke upon hand entry, the arms move towards a nearly streamlined position. During the hand entry phase of the stroke the extended arm is responsible for maintaining body alignment and setting up for the catch phase. The shoulder is often looked at as the primary stabilizer in this position, however the shoulder cannot be stable without the scapulae.
The scapula has to be sustained in upward rotation and slight protraction. This puts a demand on the upper trapezius and serratus anterior. Without proper alignment in this outstretched position, the water resistance can impinge the shoulder. If the periscapular muscles fail to stabilize the pressure on the lever arm is transferred into the shoulder joint itself.
Force Generation
Throughout the catch and pull phase the arm is responsible for creating propulsion forward. The largest pitfall during this phase is when the scapulae is allowed to "wing" off of the
body as the shoulder internally rotates to maintain proper elbow positioning. Without the strength of the lower and middle trapezius combined with serratus anterior strength the scapulae is no longer positioned properly for aiding in force generation through retraction motion.
Allowing the scapulae to separate from the thoracic wall redistributes the force applied through the upper extremity from the shoulder blade and scapular stabilizers, into the shoulder joint. As we discussed in our previous posts, the shoulder girdle muscles often fatigue enough that the connective tissue begins to be used to generate force. Building periscapuar strength will aid in scapular positioning, force distribution and will aid in maintaining non-contractile structures within the shoulder.
Range of Motion
We named this range of motion because of the implication. In this case we are referring to the recovery phase of freestyle and butterfly. Recovery for both of these strokes requires upper extremity range that allows for the arm to clear the water while maintaining a low profile in the water. Many younger swimmers who have not fully developed their stroke will often create this recovery motion by extending the shoulder while keeping the scapulae positioned with a forward tilt and protraction.
This portion of the periscapular involvement refers to the motor control ability to generate scapular movement as the arm recovers, also known as scapular dyskinesia. This requires the swimmer to depress/retract, then elevate/upwardly rotate/protract in succession to aid in arm clearance. During this phase with decreased strength and motor control, the shoulder blade can create pathologic positioning during recovery and leading up to hand entry.
Thank you for your time! Tomorrow we will discuss training shortfalls in our last Swimmer's Shoulder Series post. Always feel free to reach out via email or social media. Be sure to like our Facebook page and sign up for our mailing list.
Sam LaRiviere & Dan Fay
Grandeur Movement Science