Four count exercise: begin standing position with legs shoulder-width apart, knees slightly bent. On count 1, bend forward at the waist flexing torso. On count 2, bend torso laterally. On count 3, extend torso backward and on count 4, bend torso laterally to the remaining side. When bending backward, keep legs slightly bent to avoid hyperextending back.
Muscle-abdominal muscles, including obliques and hip flexors