What muscle group is primarily targeted during the Arms Sitting Series Rhomboids exercise?

The Arms Sitting Series Rhomboids exercise primarily targets the posterior deltoid muscle group, which plays a key role in shoulder function and stability. The posterior deltoid is responsible for the extension and external rotation of the shoulder joint. During the exercise, as the arms are moved away from the body and then brought back, the activation of the posterior deltoids helps to stabilize the shoulder and promote proper alignment, facilitating the efficient movement of the scapulae.

Engagement of the posterior deltoids also assists in counterbalancing the anterior muscles of the shoulder, preventing the common postural issues associated with overactive anterior muscles, such as rounded shoulders. This focus on the posterior deltoids is crucial for developing balanced shoulder strength and improving overall upper body mechanics, which is an essential component of a well-rounded Pilates practice.