The popularity of unilateral lower body training as it relates to athletic performance is at an all-time high, and rightly so. In comparison to bilateral alternatives, single-leg exercises are generally heralded as being more “functional” and specific to sport, safer to perform, and better for injury prevention/reduction (among other benefits). As a result, exercises like split squats, lunges, and rear-foot elevated split squats have become a staple in most modern-day strength training programs.

What’s often overlooked, however, is that while all of these exercises are undoubtedly phenomenal, they’re not entirely unilateral due to the support (albeit small) of the non-working leg. For example, it’s been estimated that the back leg takes on about 15% of the load in a rear-foot elevated split squat and up to 40% of the load in a regular split squat. Granted, that enables them to be loaded to a greater extent, which is advantageous for a number of obvious reasons. Still, they’re only partially unilateral, or—as some coaches have categorized them—“supported” single-leg exercises (credit to Mike Boyle for coining these terms).

“True” unilateral exercises, on the other hand, are entirely unsupported—meaning they force the working leg to take on all of the work without any assistance. As a result, these unsupported options—namely single-leg deadlifts, one-leg squats, and skater squats—offer some unique benefits. That’s not to say that unsupported exercises are better than their supported counterparts by any means, but rather that they should be a part of virtually all athletes’ training in order to round out a well-designed program.

In particular, here’s what separates unsupported single-leg exercises from the rest of the pack:

• True “sports-specificity.” Most movements that occur in sport—sprinting, changing direction, etc.—take place almost entirely on one leg. This makes unsupported single-leg work as “sports-specific” as it gets in the context of the weight room.
• Pelvic stability. Pelvic instability diminishes the amount of force that can be absorbed, stored, and released, which subsequently results in longer ground contact times and shorter stride lengths. In this respect, unsupported single-leg exercises are unparalleled due to the fact that their pelvic implications—and thus their ability to improve pelvic stability—are entirely different than those present in supported single-leg alternatives.
• Inter- and intra-muscular coordination. Unsupported single-leg training challenges inter- and intra-muscular coordination—the coordination between and within muscles, respectively—unlike any other lower body exercise. Considering that the growing consensus in the sports performance world is that muscle coordination patterns (i.e., getting the “right” muscles to contract and relax at the right times) are among the most important determinants of sprinting speed, this makes unsupported single-leg training a must-do.

• Tri-planar stability. Unsupported single-leg exercises occur in the sagittal plane, but they’re essentially tri-planar in that they force the lower body “stabilizers”—namely the hip rotators, adductors, and glute medius—to resist movement in the frontal and transverse planes. On top of the fact that these multi-planar demands are valuable for enhancing joint stability, they also have a direct carryover as it relates to the sprinting motion. The functions of the hip rotators and glute medius, for example, include abducting the hip, stabilizing the pelvis, and eccentrically controlling hip internal rotation and adduction. Likewise, the adductors (primarily the adductor magnus) have been shown to act as the third most powerful contributor to hip extension, which is obviously a critical component of the sprinting motion.
• Body awareness and proprioception. The proprioceptive benefits of unsupported single-leg exercises could make for an entire article, but the premise is that—when performed properly—the exercises spur a cascade of positive adaptations throughout the entire kinetic chain. They improve motor control and body awareness, reinforce “feeling” the entire foot, promote core stabilization in all three planes, and strengthen the intrinsic muscles of the feet, which can work wonders for improving function from the ground-up.
• Injury prevention/reduction. It goes without saying that injury prevention/reduction is an incredibly complex topic. Still, there are a handful of tried-and-true principles that are widely accepted as a means to reduce injury risk, such as reinforcing optimal movement mechanics, minimizing potentially harmful asymmetries/imbalances, enhancing joint stability, strengthening the muscles and connective tissues, and improving decelerative and landing abilities. Unsupported single-leg exercises address all of these components (and more) to an even greater extent than their supported counterparts—which, to be clear, are still valuable for reducing injury risk—and are thus a potent tool in the injury prevention/reduction toolbox.

The Big Three: Single-Leg Deadlifts, One-Leg Squats, and Skater Squats

The unsupported “Single-Leg Trifecta” of single-leg deadlifts (SLDLs), one-leg squats, and skater squats are all unique in that each involves a different movement pattern. As a result, all three exercises have a number of distinct benefits.

Within each description detailed below, there are three components:

1. What separates them (and why it matters)
2. How they can be progressed/regressed
3. The main points of focus.

Single-Leg Deadlift

Also known as single-leg RDLs, SLDLs are the most hip-dominant movement in the unsupported single-leg category. Like any other hip-dominant/hinge movement, they primarily target the glutes and hamstrings. Unlike most hip-dominant/hinge movements, however—most of which are bilateral—they do so in a unilateral fashion.

Benefits

Aside from the hip-dominant element, three other qualities separate SLDLs from one-leg squats and skater squats.

1. They’re the easiest of the three movements to load sufficiently. In fact, many advanced athletes are able to handle loads of greater than 50% of their 1-RM conventional deadlift with SLDLs, which—in and of itself—makes them a game changer for building single-leg strength.
2. They involve more muscles/muscle groups than their unsupported counterparts. The hamstring group is stretched while working to stabilize the knee joint, the glutes are acting concentrically to extend the hip, the lumbar extensors (low back) are working to keep the spine in neutral, and the upper back is tasked with stabilizing the scapula while keeping the thoracic spine in extension. Moreover, SLDLs place an increased emphasis on activation in the feet, ankles, and calves, which subsequently enhances neural drive and motor unit recruitment all the way up the kinetic chain. In other words, SLDLs are far more than a posterior chain exercise—they’re a full-body exercise.
3. SLDLs are arguably the most “acceleration-specific” exercise from a muscular standpoint. The posterior chain is providing all of the horsepower, the hips are moving in a reciprocal fashion akin to a sprint (alternating between flexion and extension), the pelvis and lower back are working to maintain a neutral spinal position, and the core is resisting external rotary forces while linking up the upper and lower halves. Most importantly, all of these muscular actions are taking place while the body is simultaneously working to generate force.

Progressions

SLDLs are meant to be performed in an unsupported manner, so the initial focus should be placed on grooving the single-leg hinge pattern without support before adding load.

• TRX-assisted (with one arm): progress when the athlete can perform the movement without support
• Reach to target: progress when the athlete has mastered the pattern to a low target
• 1-DB/KB:* progress when the athlete is able to use heavier loads (general guideline: .5x bodyweight)
• 2-DB/KB: progress when the athlete is able to use heavier loads (general guideline: .75x bodyweight)
• Barbell/trap bar

*Many athletes find it harder to balance with one DB/KB compared to two, so using two lighter DBs/KBs can be useful as a teaching tool.

Points of focus

• Keep a slight bend in the knee of the support leg; not straight or overly flexed
• Bring the weights down in line with the toes/mid-foot; avoid forward drift
• Maintain level hips and a neutral pelvis; avoid rotating in the torso or rear leg
• Keep the shoulder blades pinned back; avoid excess thoracic flexion
• Stay within an optimal range of motion; avoid excess depth at the expense of stability

Additional notes

• With one DB/KB, contralateral loading is typically better for athletes due to the fact that 1) most movements are contralateral and involve reciprocal patterning by nature, 2) it emphasizes pelvic internal rotation and glute activation on the working side, and 3) it challenges rotary control to a greater extent (whereas ipsilateral loading does not).
• Keeping the rear leg bent is generally preferable to keeping it straight, as it’s more akin to sprinting (reciprocal hip extension and flexion), facilitates better mechanics, and promotes increased activation in the hip extensors of the support leg.

One-Leg Squat

One-leg squats—which, for the record, are not the same as pistol squats—are the most knee-dominant movement in the unsupported single-leg category. Despite that, however, one-leg squats have actually been shown to activate the glute medius to a greater extent than SLDLs.

Benefits

1. They involve an upright torso. One-leg squats involve an upright torso position, which requires the working leg to generate force from above-to-under the hips as the chest remains tall. In a sense, this mimics the actions that occur while an athlete is at top speed. Think about it: during the sprinting motion, a powerful and stiff foot strike occurs underneath the hips while the torso remains upright. At the same time, the pelvis remains fairly neutral as the hips work in a reciprocal fashion. Moreover, the glutes—which do the majority of the concentric “pushing” during a one-leg squat—play a huge role in contributing to a powerful foot strike during the sprinting motion.

2. They up the ante on the stability and proprioceptive demands. One-leg squats challenge motor control and joint stability unlike any other movement. Whereas single-leg deadlifts require tri-planar stability to a degree, one-leg squats amplify those demands due to the extra knee flexion and inherently upright torso position. In turn, there’s a higher center of mass, which makes the one-leg squat significantly more challenging in terms of loading, stability, and balance.

3. If SLDLs are the most acceleration-specific exercise from a ‘muscles-involved’ standpoint, one-leg squats are the most sport-specific as it relates to positioning. When an athlete is changing direction or transitioning between acceleration and top speed, they’re standing on one leg and performing a partial squat while simultaneously generating force. In addition, most of the jumping and landing that occurs in sport—as well as in training, for that matter (e.g., bounds)—involves a partial, one-leg squat in similar fashion.

4. They involve a greater range of motion than virtually every other unilateral alternative. When an athlete gets to the point where they can perform one-leg squats throughout a full range of motion, they’re reaching a parallel femur position. This involves a larger range of motion than other knee-dominant exercises like split squats, rear-foot elevated split squats (for most individuals), and even skater squats, once progressed. As a result, one-leg squats increase the need for pelvic stability—which, as mentioned previously, plays a huge role in sprinting and changing direction—and enhance joint stability in a manner that’s tough to replicate.

Progressions. Like SLDLs, one-leg squats are meant to be performed without support from the non-working leg, which means that the initial focus should be placed on being able to reach a parallel femur position (unassisted) before adding load.

• TRX-assisted: progress when the athlete has the pattern down
• Kickstand/ball-support: progress when the athlete no longer needs support
• One-leg squat to box: progress when an athlete can reach a parallel femur position
• One-leg squat off box: progress when the athlete can reach a parallel femur position
• Add load via weight vests, chains, or goblet loading

Points of focus

• Hold 5-10 lb. plates/DBs as a counterbalance to shift the center of center of mass forward
• Press the counterbalance out to about shoulder height on the eccentric
• Use the box as a target; avoid “resting” or sitting down
• Maintain level hips and a neutral pelvis; avoid excess rotation
• Keep the spine in neutral; avoid lumbar/thoracic flexion
• Maintain a stacked position at the ankles, knees, and hips; avoid valgus collapse

Additional notes

• If a lack of ankle mobility is a hindrance to depth, slightly elevate the heels.
• When standing on an elevated surface, dorsiflex the ankle of the non-working leg and lightly tap the heel on the ground to minimize its contribution.

Skater Squat

Skater squats are unique in that they’re a hybrid movement between one-leg squats and SLDLs. Although unilateral and involving lighter loads, in a sense skater squats are a lot like trap bar deadlifts in that they mesh the squat and hinge patterns while challenging both the anterior and posterior chain.

Benefits

While this hybrid component doesn’t necessarily make skater squats better or worse than their unsupported counterparts, what it does do is give them three particular benefits.

1. From a muscular standpoint, they do it all. By meshing the squat and hinge patterns, skater squats hammer the quads, glutes, and hamstrings with constant tension and high levels of intra-muscular activation on each rep. This makes them an especially joint-friendly option for spurring hypertrophy in the lower half while placing virtually zero stress on the spine. Mike Boyle, for example, has used skater squats as an alternative to trap bar deadlifts for athletes with low back pain.

2. They challenge dynamic cross-body stability. Whereas one-leg squats and SLDLs primarily involve flexion and extension at the knees and hips (respectively), skater squats emphasize both actions across the body and within the same movement. In other words, the skater squat involves more “moving parts,” so to speak, which increases the cross-body stability demands. As a result, the core is forced to maintain stability on both sides of the body while the lower half moves dynamically and in a reciprocal fashion, the same of which can’t be said about SLDLs or one-leg squats.
3. They’re “self-correcting.” Due to the highly technical nature of the skater squat, it’s virtually impossible to get away with less-than-stellar movement mechanics. If there are any breakdowns in technique—whether it’s valgus collapse, lumbar flexion, subpar core stiffness, or passive foot mechanics—skater squats will expose them. This makes them very self-correcting, as they heighten body awareness, provide immediate feedback, and reinforce optimal technique almost by default.

Progressions. As is the case with SLDLs and one-leg squats, the first priority should be to own the unsupported skater squat before adding load. The following sequence of progressions should do the trick:

• TRX-assisted, decreased range of motion: progress when the athlete no longer needs assistance to reach the set target
• TRX-assisted, full range of motion: progress when the athlete can reach adequate depth (a 2-3” pad) without assistance
• Baseline skater squat*: progress when the athlete can perform 6-8 unsupported reps (to a 2-3” pad)
• Increase the range of motion: progress when the athlete can reach a parallel femur position
• Add load via weight vests, chains, or goblet loading

*If necessary, an intermediary option is to do eccentric-only reps as a transition into the full skater squat

Points of focus

• Hold 5-10 lb. plates/DBs as a counterbalance to shift the center of center of mass forward
• Press the counterbalance out to about shoulder height on the eccentric
• Keep the rear leg bent at about 90 degrees
• Use the pad as a target; avoid “resting” or sitting down on the rear leg
• Maintain level hips and a neutral pelvis; avoid excess rotation
• Keep the spine in neutral; avoid excess lumbar/thoracic flexion
• Place an increased emphasis on maintaining a neutral knee position; avoid valgus collapse

Programming Recommendations

Like any other exercise, the simplest answer to when and how unsupported single-leg exercises should be programmed is “it depends.” Generally speaking, however, a good strategy is to include both unsupported and supported options into a well-rounded program to maximize their respective benefits.

Some athletes who perform split stance movements more frequently in their sport—like baseball and softball players, for example—may benefit from placing a greater emphasis on supported single-leg exercises like split squats and rear-foot elevated split squats. On the other hand, athletes who move primarily on one leg at a time—sprinters being the most obvious example—may find it worthwhile to include more unsupported options into their training. Regardless, all athletes can (and should) perform a hefty dose of both, given that there are tremendous benefits to each.

In terms of how unsupported single-leg exercises should be programmed, there are two different approaches. Generally speaking, weaker athletes or athletes with subpar movement quality may benefit the most from performing unsupported single-leg work at the beginning of their training when they’re fresh. Stronger and more advanced athletes, on the other hand, tend to able to successfully perform unsupported single-leg exercises regardless of how they’re programmed. For these athletes, programming them at the tail-end of a session may be more beneficial to “fill in the gaps,” so that the primary focus can be placed on heavy supported single-leg work (due to their higher loading capacities). SLDLs may be the one exception due to their similarly high loading capacities, in which case they can fit in exceptionally well as a primary strength movement.

Still, regardless of how they’re programmed, each of the three unsupported single-leg exercises are all but guaranteed to provide massive benefits for all athletes no matter their age, sport, skill level, or starting point.