Even though much of the exercise we do is bilaterally balanced (both arms together or both legs together) the reality is that most tasks in the real world are unilateral (one arm or one leg at a time). By using two limbs during exercise, we are symmetrically balanced and we load the body very evenly. This puts much less stress on your trunk which allows the muscles to work to a much higher level of resistance. However, when you start a lawn mower, throw a ball or step on the brake on your car you typically do it with one limb. Although at first glance that may seem to be undesirable, it is both unavoidable and offers some hidden benefit. By loading the body asymmetrically, core muscles are engaged to stabilize the trunk. The next time you get on a chest press, row or leg press, try using one limb at a time to do the exercise. It may take a little longer but you won’t need as many crunches or back extensions to tone up those abs and back.