Which principle focuses on maintaining alignment and control during movements?

The principle that focuses on maintaining alignment and control during movements is centering. This concept emphasizes the importance of engaging the core and stabilizing the body in order to execute movements effectively and safely. Centering involves harnessing the body's center of gravity, which enhances balance and control while performing exercises on the Reformer. By focusing on this aspect, practitioners can improve their overall alignment, reduce the risk of injury, and ensure that movements are performed with intention and integrity. This principle is foundational in Pilates, as it sets the stage for proper execution of all other techniques and movements, ensuring that the body moves harmoniously and efficiently.