Many of today’s strength training exercises involve moving both arms in the same direction at the same time, or both legs. These movements require holding onto a barbell, or long handle on a cable. Bench press, military press, dead lift, squat, barbell curl, and the clean and jerk are several examples of barbell exercises. There are also strength machines found in most health clubs such as the leg press, hack squat and biceps curl or leg curl machine. These are not bad exercises but if they are the only ones you choose then it would be like reading a book but only choosing the even pages. You’re missing the other half of the story.
Think of how the body moves. As we walk, do both legs move in the same direction at the same time? Do both arms swing forward or backward at the same time? No, of course not. While one leg travels forward the opposite travels back. The arm swing opposes the leg swing action. This movement pattern not only acts on the core and connects the pendulum-like forces generated by both the arms and legs, it allows the spine to rotate, flex, extend and side bend. It also allows the hips, rib cage and skull to move in opposing directions. It is a beautiful dance-like action to walk.
Bilateral strength training (e.g. using a barbell) has a tendency to restrict spinal movement. It encourages stiffness along the spinal column. There are times in life when we do need to perform such movements (lifting, stooping, squatting, hoisting, etc.). So it is appropriate that we train the body to be stronger in this manner.
However, there are many more times in our daily life when we use our bodies in a way that demands fluidity, three-dimensional dynamic movement, and dynamic stability (walking, jogging, running, swimming, playing sports, house chores, reaching, twisting, etc.). Ask yourself, “Am I choosing the exercises to be better at performing my sport and daily activities or am I choosing them because I read them in a book or some health club employee was trained to show me the fancy machines?”
Unilateral strength training (moving one limb at a time) is the “odd pages” of your book. It completes the story. It allows the body to move differently than both limbs moving in the same direction at the same time. The next time you workout try moving one arm or one leg at a time rather than both. Try a 1-arm cable press or a single leg squat. Try a 1-arm lat pulldown or a single leg dead lift. Get a better sense of how your body moves when this occurs. We get so accustomed to our workouts, that just by tweaking the movement a little will challenge your body more than you might imagine.