The exercise ab crunch primarily works the muscles Abdominals and secondarily works the muscles Oblique abdominals.

Proper position lie on your back. Place your feet on the floor, hip-width apart. Bend your knees and place your arms on the power roller. Movement and breathing Contract your abs and inhale deeply. Exhale as you lift your upper body, keeping your head and neck relaxed. Bring your knees up to chest level. Inhale and return to the starting position.

Proper position lie on your back. Place your feet on the floor, hip-width apart. Bend your knees and place your arms on the power roller. Movement and breathing Contract your abs and inhale deeply. Exhale as you lift your upper body, keeping your head and neck relaxed. Bring your knees up to chest level. Inhale and return to the starting position.