Bent Arm Medicine Ball Twist Show Video Show All Exercises     Primary Muscle Group: Abdominal Obliques Muscle Groups Worked in This Exercise: Psoas Major, Iliocastalis lumborum, Iliocastalis thoracis Preparation: Stand holding medicine ball between hands as pictured with elbows bent. Legs slightly bent and back and head straight up. Breathing: Breath out on the contraction of the muscle and breath back in on the way back to the start position. Execution: Twist torso to one side focused on squeezing your oblique area and then rotate to the opposite side to complete the exercise movement. Here are a few suggested alternative exercises: Ab Crunch Obliques Ball Crunch Traditional Dumbbell Side Bends Lateral Bend with Barbell