Working the body this way – called unilateral training – is an often-overlooked exercise technique. It’s critical for improving functional strength, correcting muscle imbalances, rehabbing injuries and increasing stability, explains Erica Suter, a Baltimore-based certified strength and conditioning specialist. By loading and working each side of the body separately, unilateral exercises allow you to address each side’s unique strengths, weaknesses, movement patterns and needs.
After all, if you’ve ever tried to write with your non-dominant hand, you know that your left and right sides don’t work exactly the same way. That’s also true for the muscles throughout your arms, legs, back and core. The size and strength of your left and right sides’ musculature, as well as your neurological system’s ability to coordinate those muscles’ movements, can vary greatly, says Mark Barroso, a New Jersey-based certified personal trainer and Spartan SGX coach.
Side-to-side differences are normal, but they aren’t healthy, Barroso says. Muscle imbalances can increase one’s risk of injury – both in the gym and real life, he explains. However, unilateral training can help correct these imbalances while also training total-body stability.
For example, a 2012 European Journal of Applied Physiology study found that standing single-arm dumbbell shoulder presses train the core muscles to a significantly greater degree than double-arm shoulder presses. Single-side exercises also increase strength and stability in the worked joints, such as shoulders, wrists and ankles.
What’s more, when injuries do strike, unilateral training can help rehab them, says Kyle Brown, a San Diego-based celebrity trainer and certified strength and conditioning specialist. That’s because they allow exercisers to train around injured muscles or joints as well as indirectly strengthening them via a neurological phenomenon called cross education. In other words, working your left arm will also strengthen your right one, even if it’s in a cast or sling. And a 2017 meta-analysis published in the European Journal of Applied Physiology found that unilateral exercises strengthen the unworked side of the body by an average of 11.9 percent.
So how do you get the most out of unilateral training? Below, trainers share six tips for incorporating the strategy into your workout routine.
Test both sides of your body. “Unilateral training is one of my go-to methods for seeing any asymmetries in clients,” Suter says. “I am able to see if they have a lack of hip strength on one side or are more balanced on a certain side of the body. Knowing all of this gives me a better idea on how to program and strengthen certain areas.” Try performing basic movements such as lunges, single-leg sit-to-stands (where you put all of your weight in one foot, sit down onto a bench and stand back up) and single-arm chest and shoulder presses with one side and then the other. Notice any differences between the sides in terms of how much weight you can use, the number of reps you can perform and how stable you feel.
Work your weaker side first. When training one side at a time, “it’s better to start with your weaker side first when you have better stamina and neurological control,” Brown says. For each set, perform all reps on the weaker side; then, move onto the stronger one. Unless it’s unfeasible due to injury, use the same level of resistance for both sides.
Master the basics. The body’s basic movement patterns include the squat, lunge, deadlift, push, pull, rotation and anti-rotation, where you resist a force that’s trying to rotate your torso, or stability. All single-sided movements should follow suit. Focus on single-leg squats (you can add assistance by holding onto TRX suspension straps), front, side and rear lunges, step-ups, single-leg deadlifts, single-arm chest and shoulder presses, single-arm rows and pull-downs or wood chops, Barroso recommends. He also suggests Pallof presses, an exercise that involves holding an anchored cable handle or resistance band and pressing it straight in front of the body and resisting the sideways pull of the cable on your torso.
Avoid stability balls and barbells. “The fact that you’re using one limb is already adding instability; you don’t need to make the training environment super unstable by adding a stability ball,” Barroso says. He also notes that barbells are intended to be held with two hands and can easily become unstable when held with one. “Use dumbbells or kettlebells for loaded multi-joint unilateral movements [like lunges, deadlifts, presses and rows],” Barroso says.
Use unilateral movements as accessory work. Most people will benefit from performing bilateral compound moves such as traditional two-sided squats, deadlifts, rows and presses as the foundation of their exercise routine and using single-sided moves as a complement. “Depending on the client’s goals and limitations, unilateral training should account for at least 40 percent of all exercises,” Brown says. Both he and Barroso note that some people, especially exercisers such as runners and swimmers who use one side of the body at a time, may need even more. Perform single-sided exercises after performing bilateral compound moves, Barroso says.
Start light and work your way up. The instability introduced in single-side movements can reduce the total amount of resistance you can lift or otherwise move with each repetition. For example, you may not be able to single-leg deadlift a full 50 percent of the weight you could deadlift using two legs, Barroso says. Use light weights to ensure proper technique before increasing weights to 50 percent or even more. Some individuals have a bilateral deficit, in which the sum of force that each limb produces during unilateral exercises is greater than the force produced during the same exercise performed bilaterally, he explains. Remember, it’s possible that once you’ve perfected your form, you can single-arm shoulder press more than half of what you could during a two-arm shoulder press.