Put on a potato sack. Now try to play football. It’s impossible because your legs are fused together as one unit, and to run, lunge, weave, and backpedal you’ve got to use your legs separately.
It’s rare in sports to be doing the same thing with both legs or both arms at the same time, especially with the same force or velocity. Yet the vast majority of strength exercises are done bilaterally—with both sides at the same time. Think: pullups, pushups, and barbell curls.
The thing is, despite what your mother told you, no one is perfect. We all have a bigger foot, a larger biceps, and a weaker side. We prefer one side over the other for writing, kicking, throwing, or hitting, a preference that inevitably creates an imbalance, making one side of your body stronger, more agile, and more adept than the other. In fact, a study published in the Journal of Science and Medicine in Sport showed that strength differences between your limbs can be as much as 25 percent.
You might not even realize there’s a strength disparity between your sides, especially if you perform mostly bilateral movements in your training. With something like a barbell curl, for example, your stronger arm will compensate for the weaker one to do the lift, essentially masking an asymmetry or a weakness that may have developed. Imbalances such as these could lead to ineffective movement patterns, compromised joint and tissue integrity, and even injury over time.
Your Solution: Divide to Conquer
Training unilaterally—one side at a time—can help correct imbalances that may arise from sports or everyday activity, preventing injury by increasing individual limb strength, and improving agility, performance, and speed.
A study in The Journal of Strength & Conditioning Research found that unilateral exercises helped develop unilateral strength. Sounds obvious, but better collective unilateral strength amounts to increased bilateral strength by proxy. Back to the barbell curl: If you strengthen both arms separately using heavy dumbbell curls, you’ll eliminate the weak link. Both arms will pull their own weight (literally) when doing a barbell curl, which means you can lift heavier loads as a result.
Several studies also confirm that training unilaterally leads almost magically to increased strength gains in both sides. Let’s say you were to do a dumbbell biceps curl with your left arm only over the course of several weeks. Research shows that your right arm would experience up to a 22 percent increase in strength, even though it was not being directly stimulated. Researchers theorize that the non-working side still receives indirect nervous stimulation, as well as its fair share of oxygen, nutrients, and hormones, which could lead to increased growth and strength.
Moreover, training unilaterally can give you a core of steel, according to another study published in The Journal of Strength & Conditioning Research. Movements such as a one-arm overhead press recruit more stabilizing muscles in the core and trunk, giving you more strength, stamina, and stability for sports and everyday activities—and when performed standing rather than sitting will further increase core engagement.
Even though unilateral training is amazing, don’t kick bilateral training to the curb. It still has a place in terms of functional and neuromuscular adaptations, and besides—can you imagine a week without squatting? Simply add unilateral training into your rotation, focusing on moves and drills specific to your sport or activity, or ones that target a specific imbalance that needs correcting.
5 One-Sided Moves You Should Master
Here are a handful of great unilateral moves to try. Organize them into a circuit or metcon, or pepper them throughout your training week. Do all reps on one side of your body, and then switch to the other side without resting.
Stand on one leg. Keep your other knee straight and extend that leg in front of you. Keep your hips square as you push your glutes back and bend your standing knee, extending your arms in front of you for balance if needed. Lower as far as you can without tilting or allowing your heel to lift off the floor, then stand back to the start. If you’re new to this exercise, you can sit on a chair or box (shown) to guide you. Then, after you master the range of motion, transition to free space.
Get into a pushup position with your hands on a set of dumbbells (or Spartan pancake, shown) and your head, hips, and heels aligned. Spread your feet apart a bit wider than you would normally for a pushup to maintain balance, and then pull the dumbbell up toward your rib cage, leading with your elbow and keeping your arm close to your side. For maximum core engagement, do not allow your body to twist or tip side-to-side as you row.
Unilateral Shoulder Press
Stand with your feel hip-width apart, knees slightly bent, and hold a single dumbbell or Spartan pancake above your shoulder at ear level, palm forward. Extend your arm straight up overhead to full extension, then lower slowly back to the start.
One-Legged Hip Thrust
Lie face up with your knees bent, feet flat on the floor and your heels close to your glutes. Extend one leg straight up over your hips, then press through your grounded heel and lift your hips so your thighs and knees align. Pause briefly then lower almost to the start before pressing right into the next rep.
Unilateral Loaded Carry
Hold a kettlebell, heavy dumbbell, or Spartan pancake at your side and square your shoulders and hips. Brace your core and take small, quick steps forward. Stop, switch hands, then walk back to the start. You can do carries for time or distance.
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