A simple and easy way to work your side torso muscles is to turn sideways and perform side crunches. If the movements are done properly, you won't see a large range of motion, but you will feel an intense contraction on the outer side of your abdominals. You can perform this move either on a flat mat or on a Bosu trainer.
1 If you are using a Bosu trainer, position the right side of your torso on the dome with your bottom leg bent and your top leg straight. If you are working on the floor, lie on your right side, bending both knees toward your chest. Place your left hand behind your head, pointing your elbow up toward the ceiling. Rest your right hand on your left shoulder. Inhale.