If the rotator cuff is active, the glenohumeral joint is stabilized, and the scapulae are more free to mobilize on the rib cage (with the serratus anterior), there will also be more freedom in the thoracic spine to extend and in the rib cage to breathe. Mobility in the thoracic spine is important; much like in upward-facing dog, the more extension there is in the thoracic spine, the less the lower back and cervical spine have to do.

The triceps and deltoids are eccentrically very active, to resist falling forward on the face or head. This is a great preparation pose for handstands because it strengthens the arms.

If tightness in the forearm (either in the supinators or in the interosseus membrane between the radius and the ulna) restricts full pronation, the elbows will swing open or the hands will come together. This common forearm issue is often interpreted as tightness in the shoulders or weakness in the wrists.

Shortness in the latissimus dorsi can also pull the elbows wide, by internally rotating the humerus. This can feel like tight shoulders, but can actually be addressed by side bending and other actions that lengthen the latissimus dorsi. Shortness in these muscles will also cause too much lumbar extension and interfere with breathing.