Unilateral leg training is great for you.  Plain and simple.

For the athletic population, and especially one-side dominant athletes like baseball players, a big differential can develop between legs.  Pitchers will often have increased tightness in their stride leg, especially in the hip joint (from rotating on it with each pitch), yet higher strength in their balance leg (chiefly from balancing, loading, and pushing off with it 100 times per game).

The disparity can be in flexibility, mobility, or strength, but no matter the symptom, unilateral training is always a big part of the cure.  And, if you have a weak leg your regular bilateral lifts (squats, deadlifts, etc.) are needlessly suffering.  Big strength gains can happen in those regular lifts from strengthening the weak link.

The two most prevalent uni-leg squats are the Pistol Squat and the Peterson Step-Down, but I’m also going to throw the rear-reaching uni-leg squat into the mix, which is a better variation of the pistol squat for a few reasons.

Pistol Squat

Take a close look at the above video.  It’s important to notice two things about the pistol squat:

1. The back is very rounded, which might not cause problems if done with bodyweight, but would be a serious injury risk if additional weight is used.

2. Weight shifts way back on the heels, which puts more force on the knee than if the weight was more centered.

For the above reasons, I am not a fan of pistol squats.  If the off-knee is bent it allows better weight distribution, but even then I think there are better options.

The Rear-Reaching Uni-Leg Squat

Rear-reaching variation of the one-legged squat

The key to this exercise is to touch the knee down before the back foot.  Usually range of motion calls for a 2 inch pad (maybe higher, depending on the squatter’s height) to touch the knee to before coming back up.  Because the weight is shifted backward, the quads really get worked, and there is a high degree of difficulty in getting that knee down first.  The thigh gets to parallel, which is perfect, but if you wanted to go deeper, this wouldn’t be the exercise for you.

Notice anything about this picture?  The back stays super straight with relative ease, which is a big plus for this rear-reaching version.  A far cry from the rainbow back of the pistol squat.

Because of the difficult mastery of this one, adding weight is usually not necessary, though it would be easily tolerated with such good spinal posture.

This is definitely a quality exercise, and worthy of addition to one’s unilateral repertoire.  It was developed and is frequently used by Nick Tumminello at Performance University.

The Peterson Step Down

Who is Mr. Peterson?  I have no idea.  I just know that I learned these by that name.  By most accounts these are probably just referred to as box step downs, or one-leg squats from a box.

There are a few reasons I like this version the best:

1. The back is straight, which allows additional weight to be used

2. The weight stays more centered, which won’t put extra stress on the knees

3. It just feels comfortable and fluid throughout the range of motion, which encourages the use of extra weight.

4. Allow a large a range of motion as desired

The Final Word

Pistol squats may be okay for some people, but in my experience they catch up with you in the form of knee pain.  I’m a fan of squatting deep with all variations of squats, but pistols just seem to make a lot of people’s knees angry at them.

The rear-reaching variation is an excellent choice, but just isn’t my personal favorite.  I prefer the Peterson, which allows for complete ROM, a middle center of gravity, and the easy addition of extra weight.

Which variation is right for you?  I would recommend avoiding the pistol altogether, which leaves two great alternatives that can really give a boost to one’s unilateral leg training.