Using the Single Leg Squat to Test Leg Health

The single leg squat isn’t just a great strength-building exercise, but it also helps assess leg health. A new study discusses the importance of knee tracking and how to correct it.

The single leg squat has gained a lot of popularity in the last few years. It’s an easy exercise to build leg strength that can be done at home with little or no equipment and without a spotter. Exercise that uses one limb at a time, also known as unilateral exercise, may also help build the stabilizing muscles to increase strength and health, especially in the spine.

Not only have single leg squats become a staple of many athletes’ routines, but they can also be used as a tool for assessing the safety of all lower body strength maneuvers. If you don’t have your strength and flexibility in order, your single leg squat form will be off, and you will be able to tell. According to researchers in a study this month in the Journal of Strength and Conditioning, one such error in form is not only easy to spot, but also speaks volumes about what you need to work on to keep your lower body, especially your knees, healthy and strong.

According to the researchers, the form issue that rears its ugly head frequently during the single leg squat is called medial knee displacement. All that means is your knee moves inward. If you’ve never noticed this before on any kind of squat or deadlift, take a look next time you do a heavy set, especially toward the end. Better yet, if you’re not used to spotting it, watch other people in the gym. Before long you’ll notice it all the time.

The time to pay the most attention to medial knee displacement is at the very bottom of a squat, just as you reverse direction to begin the ascent. The start of the ascent is the most common place to spot the knee drifting inward.

During the study, the researchers found that athletes expressing medial knee displacement had some common deficits that could be corrected through training. In this study, many of the athletes had weak glutes and tight hip adductors and calves. The researchers proposed that tight hip flexors could be a culprit as well.

If you do the single legged squat test and notice your knee drifting inward at the bottom, the researchers have some suggestions. First is myofascial release of the tight muscles. What this means in a practical setting is foam rolling the inside of your thigh as well as your calves and Achilles before squatting. You may also want to stretch these areas.

The second recommendation that came out of this study is to strengthen and activate the glutes. There are a few ways to do this. Personally, I like back bridges. You don’t have to do the extreme versions, as a simple bridge on the shoulders will do. Standard back squats with a lot of depth while consciously forcing the knees outward are another option. You may need to use a lighter load to do this, and hip flexor stretching and release may also be required for some people.

Not only is the single leg squat a great exercise with increasing popularity, but it’s also a useful assessment tool. I recommend all athletes add it to their toolbox.


1. Timothy Mauntel, et. al., “The Effects of Lower Extremity Muscle Activation and Passive Range of Motion on Single Leg Squat Performance,” Journal of Strength and Conditioning Research, 27(7), 2013.

Photo courtesy of Shutterstock.

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