If you've ever been in the gym working on those buns of steel, more than likely you'll have noticed one leg seems stronger than the other. Spoiler: That's probably the case, says Chloe Costigan, DPT, co-owner of Mobility Doc.
"We are not symmetrical beings in the first place," Costigan tells LIVESTRONG.com. "And we end up doing asymmetrical activities for a variety of reasons that create more strength or flexibility in one limb over the other."
One example is writing — chances are, you grab a pen with your dominant hand every time, right?
But asymmetry isn't necessarily a bad thing, Costigan says. In fact, an asymmetrical body can be an efficient one. For example, if you're pushed, natural instinct will stabilize your dominant leg to hold you steady.
"Your body creates these patterns so it doesn't need to think about it," she says. "The problem is when dominance starts to really take over."
And we shouldn't necessarily equate dominance with strength. Your dominant hand, for example, is the one you're more likely going to use for everyday tasks, and while that can inherently lead to increased strength, that's not always the case, Costigan says.
So, why is one leg stronger than the other? Two experts share a few likely answers, plus how to address this leg strength imbalance.
Why Your Dominant Leg Is Stronger
Which leg is usually stronger? The answer is usually your dominant leg, and there are a number of reasons for this.
You Have One Dominant Hand
Often, hand dominance translates to leg dominance, Costigan says. If you're right-handed, for example, you'll usually defer to that hand for everyday tasks like holding a phone and picking up a bag. You might see that same pattern when you go to kick a ball or push something heavy — your right leg will move to the front for power.
And when you default to your dominant side for certain tasks over and over again, it's inevitable for that side to build strength.
Your Activity Requires a Dominant Side
Certain activities will default to one side over another, which is often tied to hand dominance, but not always, Costigan says. When you do asymmetrical activities or have a history of doing them — you're a former soccer or hockey player, for example — you're more inclined to have more asymmetry and expose those dominance patterns, she says.
And while running is a symmetrical activity, where you run can affect strength, unequally. A road's camber — the angle the road is designed — can play a role in which leg might be more dominant or stronger. Running on a track can also do this, if you run in the same direction over and over again, Costigan explains.
"If you're turning left [the traditional direction of track running] there is more weight on your left leg, and if your left leg is already dominant, that could cause additional stress," she says.
You Have a History of Injury
If you've had a severe injury in the past, say a torn left ACL 20 years ago, it likely still has some effect on you, Costigan says. Let's say you were right-side dominant and the knee injury forced you to rely even more on your right side — that can create an issue.
How to Test Which Leg Is Stronger
Costigan shares a few ways you can determine which leg is stronger.
Test 1: Starting from a standing position, pretend to fall and note with which leg you catch yourself.
Test 2: Jump off of one leg and then the other to see how high you can jump. If you jump higher pushing off of your left, your left is likely to be stronger. Costigan says this test should be taken with a grain of salt if you're not used to jumping regularly.
Test 3: Balance on one leg and then the other. The side that provides balance is likely going to be stronger, and often the dominant side.
Why Your Non-Dominant Leg Is Stronger
Although it's not unheard of, it's less common for your non-dominant leg to be stronger. In that case it's likely because your dominant leg is overworked, Costigan says.
For example, if your right leg is dominant but your left leg is stronger it could be because your right hip has more tightness; that can inhibit increasing strength.
When Asymmetry Becomes a Problem
As Costigan points out, it's natural to be somewhat asymmetrical. It only becomes a problem when there's pain or compensation that can affect things like gait.
"Most people end up having an injury due to cumulative strain," she says. "Over time you might slowly move in the direction of injury."
Athletes who heavily favor one side are more likely to experience an injury, Costigan says.
"That asymmetry gets exposed in athletes," she says.
The best way to prevent asymmetry from becoming a problem is to take note of how you're moving, Costigan says.
"Being an observer of yourself is key to preventing injury or addressing an issue," she says. "I noticed I do this thing on my right side but not on my left."
Or are you more flexible on one side?
That doesn't mean you have to figure out why — that's what a physical therapist is for — but it makes you more aware of yourself.
"Loss of flexibility can be due to overuse on one side," she explains, noting that you'll want to focus on how you move, flexibility, and strength and stability. "When there's enough wrong with all three areas, you'll have pain."
How to Strengthen Your Weaker Leg and Restore (Some) Symmetry
Not only are we asymmetrical beings, but everyday living has us moving on one leg at a time — for example, shifting from one leg to another while walking or running — Abby Bales, PT, DPT, CSCS, owner of Reform PT, tells LIVESTRONG.com.
"We should practice doing that in our workouts," Bales says.
Bales shares three of her go-to moves to mimic some of the one-sided living we do, which can help strengthen the weaker side.
Bales demonstrates these moves using dumbbells, but you can use just your body weight to make the exercises easier. Alternatively, you can increase the amount of weight used to make the moves harder.
1. Bulgarian Split Squat
- Stand a few feet in front of a bench, box or chair, facing away from it and holding a dumbbell in each hand.
- Reach your left foot back and place the top of your foot flat on the surface. To help with balance, widen your base of support by moving your left foot a few inches to the left.
- Lean your torso forward slightly and bend your front knee to sink your hips toward the floor as low as you can comfortably go.
- Your front-leg shin should be vertical or close to it, while your back knee should point down toward the floor. If either leg is out of place, move your front foot forward or backward until you’ve found the ideal positioning.
- Push through the middle of your front foot to return to standing.
- Complete all reps on one leg before switching to the other.
2. Single-Leg Deadlift
- Stand on your right leg while holding a dumbbell in each hand, palms facing forward.
- Keeping the right knee slightly bent, perform the deadlift by bending at the hip, extending your free leg behind you for balance or resting the top of your foot on a bench. During this movement, make sure your hips remain square.
- Continue lowering the dumbbell until your upper body is parallel to the ground.
- Keeping your back flat, return to the upright position.
- Repeat on the opposite side.
3. Reverse Lunge
- Stand with your feet about hip-width apart, arms at your sides, holding a dumbbell in each hand.
- Step with your left leg 3 feet behind you and bend your knees until they form 90-degree angles. Your back knee should hover an inch above the ground and your front thigh should be parallel to the ground (or as close as possible).
- At the same time, bring your left arm up to form a 90-degree angle.
- Keep most of your weight in the front leg as you press into your left heel and straighten your left leg.
- Bring the left leg and arm back to the starting position and stand up.
- Repeat the motion with the opposite leg and opposite arm.
Having a dominant side is normal and asymmetry is normal. But when you cross the threshold of what your body can tolerate, it changes movement, affects performance and can cause pain, Costigan says.
You don't have to make your body symmetrical, but adding in exercises that shift from one side to another in your workouts can help keep things less imbalanced.