Lateral Strength
Your lateral muscles are on the sides of your torso, and are among the hardest to exercise effectively. To feel them, sit on the floor with your knees in front of you, near your chin. Using only your abdomen, rotate your shoulders as far as you can to one side, then the other. You should feel your lateral muscles doing the work. This motion can be performed while holding a weight or medicine ball for greater resistance, or on an exercise ball, lying back or sitting up, for different effects. You can also perform a crunch with your knees lying to one side in order to train the lats.