Final answer:
The side stretch, or mermaid/Cleopatra, primarily works the obliques, lower back, and latissimus dorsi muscles.
Step-by-step explanation:
The side stretch, also known as the mermaid or the Cleopatra, is an exercise that targets several key areas in the body.
When performing this exercise, the primary muscles that are being worked include the obliques, which are the muscles on the side of the abdomen, as well as the muscles of the lower back, and the latissimus dorsi, which are the large muscles on the sides of the back that run from the armpit to the waist.
This stretch can also involve the shoulder and hip muscles, depending on the range of motion and specific variation of the stretch.