Speaker #0Hi everyone and welcome to Biopilates Deep Dive. Today I invite you to explore an exercise that may appear subtle at first glance, yet holds remarkable biomechanical depth. Internal rotation in the sidearm sitting series on the reformer. It's a movement that could easily be underestimated if we only consider its range, and yet it demands an extremely refined level of organization. It requires us to distinguish true shoulder movement from compensations in the trunk, the neck, or the shoulder girdle. It also reminds us that in Pilates, a small gesture is never a small task. In this preparation, everything begins with the starting position. We sit sideways on the carriage, legs crossed, pelvis neutral, spine neutral, in a calm, organized vertical alignment. without excessive tension. The hand closest to the pulleys holds the strap. The upper arm is placed by the side. The elbow is bent at 90 degrees. The forearm is perpendicular to the torso, and the palm faces the body. The other hand can rest on the hip. Even before the movement begins, the body is already working. The pelvis must remain stable. The ribs must stay stacked over the pelvis. The head should float naturally on top of the spine. And above all, the scapulae must be stabilized without rigidity, without gripping, without unwanted movement. This is what I find essential to emphasize. In this exercise, the movement must not be stolen by other regions. The shoulder should not lift. The thorax should not rotate instead of the arm. The trunk should not side bend to assist the movement. And the neck should not tense to help. What we are seeking here is a clear... precise, clean, glenohumeral internal rotation supported by the organization of the rest of the body but never replaced by it. Breathing plays a major role here. I inhale to prepare, then I exhale to initiate the movement. This exhale is not just a rhythm. It deepens the engagement of the center, helps connect to the deep abdominal wall, supports rib containment and limits compensatory strategies. Then I inhale to return with control without letting the carriage pull me back. In this exercise, the return is just as important as the action. To go is to produce. To return is to integrate. To go is to mobilize. To return is to stabilize. And very often, it is in the return that we see whether the movement is truly mastered or simply performed. From a biomechanical perspective, what is happening? The humerus performs a medial rotation within the glenoid cavity. In other words, the forearm rotates inward, but this should not be achieved by a global collapse of the shoulder. We want to keep the humerus as stable as possible in space while the rotation occurs within the joint itself. And this is where the exercise becomes truly fascinating because it forces us to distinguish between pure movement and compensated movement. Many people believe they are rotating the arm when in fact they are pushing the shoulder forward, collapsing the chest or shifting the ribcage. Here instead we seek a refined, centered, almost surgical action. The first muscle I want to highlight is the subscapularis. It is the primary driver of this internal rotation. It lies on the anterior surface of the scapula within the subscapular fossa and inserts onto the lesser tubercle of the humerus. Its main action is internal rotation of the arm, but its intelligence goes beyond that. The subscapularis does not only rotate, it also centers. It actively helps maintain the humeral head Right. properly positioned within the glenoid cavity. It protects the quality of the joint relationship throughout the movement. It is innervated by the upper and lower subscapular nerves, originating from the brachial plexus, primarily from C5 and C6. The second muscle I want to discuss is the teres major. It originates from the posterior surface of the inferior angle of the scapula and inserts onto the medial lip. of the intertubercular groove of the humerus. Its actions include extension, adduction, and internal rotation. It is less specific than the subscapularis in this context, but it plays a powerful synergistic role. It supports the movement, helps organize the trajectory of the arm, and contributes to dynamic stability. It is innervated by the lower subscapular nerve, also from the brachial plexus. But if I only spoke about these two muscles, I would be giving an incomplete picture. because a well-executed internal rotation cannot exist without the entire environment that supports it. First, there are the stabilizers of the trunk, the transversus abdominis, the pelvic floor, the obliques, the multifidi, the spinal extensors. These muscles do not produce the rotation, but they prevent the rest of the body from moving in its place. They create the platform, they provide the necessary stillness. so that the glenohumeral joint can express itself clearly. Then there is the scapula. And again, we must be precise. The scapula must be stable, but not rigid. It must remain wide across the ribcage, without lifting, without collapsing, without gripping. If it elevates, tips forward, or shifts excessively, then the humeral head loses its base of support. The movement becomes less... precise, less efficient, and sometimes even irritating to the joint. Muscles such as the middle and lower trapezius and the serratus anterior contribute to this support. They do not perform the movement for the subscapularis, but they create the conditions for its accuracy. This is also why the errors are so revealing. One of the most common is allowing the shoulder to roll forward. The student believes they are performing an internal rotation, when in reality they are simply moving the entire shoulder complex. Another frequent error is shoulder elevation, often accompanied by unnecessary tension in the neck. We also often observe a subtle rotation of the thorax, as if the torso were quietly helping the arm. And finally, there is the uncontrolled return of the carriage, which clearly tells us The movement was done. but not yet integrated. I also really enjoy exploring grip variations. When the palm turns upward or downward, the sensation changes. Muscle recruitment shifts. The relationship between the forearm and the humerus subtly adjusts, and this can transform the proprioceptive experience. Some individuals will feel the subscapularis more clearly. Others will perceive the teres major or posterior support chains more distinctly. These variations do not change the essence of the exercise, but they enrich our understanding of the body. What I deeply appreciate about this preparation is that it educates as much as it strengthens. It does not simply build muscle. It clarifies movement. It teaches the practitioner to feel what is moving and what should remain still. It teaches the difference between correct effort and compensatory effort. It reminds us that a strong arm is not an arm that forces, but an arm that works from refined organization, from a stable center, from a supported scapula, and from a well-centered humeral head. In an approach like ours, this type of exercise is incredibly valuable. It prepares the body for more complex tasks, pushing, pulling, weight-bearing, transitions, dynamic sequences. It enhances joint awareness. It refines the relationship between mobility and stability. And it reminds us of a simple but essential truth. The quality of a movement never depends solely on the muscle that acts, but on the intelligence of the system that surrounds it. If I had to summarize the essence of this seated side internal rotation, I would say this. It is about producing a precise movement without collapse, without tension, and without compensation. It is about keeping the scapula stable without locking it, rotating the humerus without moving the thorax, engaging the center without becoming rigid, and breathing without losing alignment. It is a work of finesse, clarity, and awareness. And that is exactly why it is so valuable. We know that the most subtle movements are often the ones that teach us the most. They require less demonstration and more listening, less brute force and more motor intelligence, less quantity and more presence. And that is exactly what this preparation offers us. Thank you very much for listening to this episode of BioPilates Deep Dive. If you enjoyed it, please share it with others. See you soon for the next episode.
