I first got serious about unilateral training—that is, working with one arm or leg at a time—last year, after ankle surgery took my right leg out of commission for three months.
During that period I was determined to do everything possible not to gain fat or get out of shape. So twice a week when my husband drove me to the gym, I did everything a person with one working lower limb could do: leg presses, knee extensions, knee curls and so on—with my left leg only.
That might sound pointless. You’d think that the functional leg or arm would get disproportionately strong while the injured one got weaker. Not so: Exercising a single limb actually helps its twin. And it turns out there are good reasons to work one leg or arm at a time, even if neither one is injured. Let’s look at what unilateral training can do for you:
1. Correct strength imbalances. Almost everyone is weaker on one side than the other. Your dominant half usually picks up the slack for the other side of your upper body, and when you always use bilateral exercise machines or barbells, you don’t notice it. But as soon as you substitute, say, the dumbbell bench press for a machine press, it becomes really obvious that your stronger side has been compensating for the weaker one. The only way to equalize that is to work each half by itself, typically with dumbbells, kettlebells or machines that allow you to address your left and right sides separately. Perhaps surprisingly, you also have a dominant leg. Try single-legged squats, leg presses, and other moves to even the score. Note that when you’re getting started with unilateral moves, it’s smart to use much lighter weights than you’re accustomed to. Working just one side makes the exercise a whole new lift. Increase the weight judiciously.
2. Build a stronger core. One-sided upper-body training has another super benefit: strengthening the postural muscles of your torso. That means your abdominals, including the obliques (which run along either side of your “six pack”), and lower back. Think “anti-rotation,” as in the muscular activity needed to remain upright when you’re carrying a bag of groceries in each hand, and one bag is heavier than the other. When you stand and do unilateral dumbbell shoulder presses, for example, your goal is to lift each weight correctly without bending or twisting sideways. You may find that you have to use less weight than you would if you were seated—or if you were standing but pressing both ’bells at the same time.
A great unilateral core exercise is the farmer’s walk, also called the farmer’s carry. All you do is pick up a dumbbell, kettlebell or weight plate with one hand, hold it by your side with your arm fully extended (straight), and walk around for a while. Start with a light weight—maybe 10 to 15 pounds—and a short walk of about 30 seconds. Repeat with the weight on the other side. Add pounds and time as you progress but only as much as you can carry without bending, leaning, or twisting. The farmer’s walk has the added benefit of improving your grip strength.
3. Reduce loss of function in an idle limb. When an injury deprives you of your usual activities, it’s so tempting to take a layoff. But there’s almost always a way to train around your limitations. And research shows that working the “good” side of your body actually stimulates the “bad” side. No, you can’t directly work those inactive muscle fibers. But your central nervous system behaves as though you did, providing a modest crossover effect. So if your right arm is in a cast but you perform exercises with your left arm, the muscles on the right will atrophy less than if you’d done nothing.
Have you tried unilateral training? Let me know in the comment box below!
Mary is a Certified Strength and Conditioning Specialist, and you can find her online at Primefitnessforwomen.com.