Single Leg Exercises for Athletes: The Kevin Carr System

Based on Episode 50 of the Just Fly Performance Podcast, a conversation between host Joel Smith and Kevin Carr of Mike Boyle Strength and Conditioning.

The single leg exercises that build durable athletes are not the circus act some coaches picture, a row of people wobbling on one foot on a BOSU ball. That is the message from Kevin Carr, a strength coach at Mike Boyle Strength and Conditioning (MBSC) and co-owner of the movement clinic Movement As Medicine, who trains everyone from US Olympians down to general population clients. His logic is hard to argue with: we live most of our lives on one leg, so a lot of training should happen there too. The point of single leg work is not balance for its own sake. It is building hips, quads, and a trunk that hold up under real, multidirectional load while keeping the athlete healthy enough to keep training.

Key Takeaways

• Train single leg because sport is single leg. We spend most of life on one leg, so single leg exercises belong at the center of athletic development, built on top of a bilateral foundation.
• Progress, do not just prescribe. Carr builds from the split squat to the rear foot elevated split squat to a single leg squat to a box, earning depth and control before load.
• Coach the single leg deadlift at the hip. Square the hips and sit into the standing hip; a cross-reaching version teaches the pattern before you ever add weight.
• Get more output with less load. A loaded single leg squat can beat a heavy back squat for cost to benefit, sparing the spine and the nervous system.
• Modify the big lifts. Trap bar deadlifts and goblet or front squats keep most of the benefit with less risk for athletes who are not powerlifters.

Why single leg training sits at the center

At MBSC, single leg work is not a gimmick bolted onto a barbell program. It is a foundation. Carr is quick to add that they still build bilateral strength for nearly everyone, teaching the goblet squat, the front squat as a path into the Olympic lifts, and trap bar and kettlebell deadlifts. But the single leg side is where a lot of the athletic transfer lives.

We live our life mostly on one leg, so we should spend a lot of time training on one leg.

His reasoning goes past specificity. Standing on one leg takes the athlete out of the pure sagittal plane and forces the hip, quad, and core to stabilize the way they have to in a sport. He also frames it as a risk and reward decision, especially for older or general population clients.

I don’t see a reason to have a middle-aged adult athlete loading heavy back squats when we could have an option to have them do a split squat or a single-leg squat.

For a coach, the takeaway is to treat single leg exercises as a main course, not a finisher: program them with intent, progress them, and let bilateral lifts build the base underneath.

The single leg exercise progression: split squat to single leg squat

Carr does not hand athletes a pistol squat on day one. He runs a progression, and most people spend weeks at the start of it.

Our athletes will split squat and load split squat, and then they might go to rear foot elevated split squat, and then on another day go toward true single-leg squatting.

The standard depth is a parallel femur on split squats and goblet squats. The true single leg squat is the one lift he treats as a partial, and he scales it carefully, often to a bench or box around 18 inches with a pad on top, then lowering the target over time.

We don’t want to see the valgus. We don’t want to see you open your hips. I want to see that you can line yourself up, and then we can start to pull away the box to a lower height.

He is candid that they almost never train a true pistol with the leg held straight out. They squat a single leg to a box for a depth marker, not to bounce off, because letting people bottom out and rebound is where he sees knee and low back problems show up. The lesson for coaches: pick a depth standard, give athletes a marker to hit, and earn range over weeks rather than chasing an impressive looking rep early.

How to coach the single leg deadlift

The single leg deadlift is one of Carr’s favorite exercises, and also one of the most commonly butchered. The usual fault is the hips opening up.

You look at a lot of single-leg deadlifts and they’re opening up their hips. They’re not able to sit into their hip and get internal rotation and actually use that glute.

His teaching fix is a cross-reaching single leg deadlift: the athlete reaches the opposite hand toward a cone lined up with the standing leg, which trains them to square the hips and sit into the hip rather than rotate open. Once that pattern holds, he loads it, moving from one dumbbell to two dumbbells or kettlebells.

That same hip stability is why he reaches for single leg work when runners and triathletes show up with the classic glute and TFL complaints.

People who don’t have good single-leg stability tend to have that typical glute TFL dysfunction because they don’t have lateral hip stability.

So the single leg deadlift earns its keep twice: as a strength exercise and as a corrective for the lateral hip that breaks down in repetitive, single leg sports like running.

Modify the big lifts: trap bar deadlift, goblet and front squat

Carr is not anti-barbell. Most of his younger athletes spend real time learning to front squat, hang clean, bench, and deadlift. But he picks barbell variations that move the center of mass into a more forgiving spot without giving up the training effect.

I can’t understand why you wouldn’t trap bar deadlift if you weren’t training a power lifter. You don’t lose anything in the motion.

The same thinking sends him to the goblet squat and front squat over the back squat for most athletes. Shifting the load forward asks less of the low back and spinal erectors, which matters when, as he points out, he might have up to 100 people training in the gym at once and needs lifts that are safe to coach at scale.

If we can start someone by teaching them to goblet squat rather than putting a bar on their back, that’s kind of a no-brainer.

His critique of the field is blunt and useful: too many coaches cannot think outside the powerlifting box. Powerlifters train the back squat and the straight bar deadlift because they compete in them. An athlete who does not compete in those lifts has no such obligation, and can take the version that distributes the load more athletically.

Train as strong as you need to be, not as strong as possible

The principle underneath all of it is what Carr calls lowest system load: get the output you need at the smallest cost to the athlete. A loaded single leg squat is his go-to example, where a weight vest and a pair of light dumbbells can make eight reps genuinely hard without a barbell on the back.

If I can get more output with less load, and then train again sooner and not have them be sore and have their CNS crushed, I just think that’s a win.

He ties it directly to longevity, especially for the professional athletes who have trained with Mike Boyle since college and are now deep into long careers.

If we can do the job with less cost, that might mean they get another season or two. They might get another contract, and that’s a big difference in their life.

It reframes the job. The question is not how much load you can pile on today, but the best choice for the person in front of you.

Whenever we build programs, we’re always thinking, what’s the highest reward with the least amount of risk, getting them as strong as they need to be, not necessarily as strong as possible.

Single leg work is really multiplanar training

Ask whether single leg lifts are sagittal plane movements and Carr pushes back. The moment one foot leaves the ground, the demand changes.

Once you pick one foot up off the ground, everything changes. Mixing in single-leg work essentially starts to give you multiplanar stability, because you have to stabilize in much different planes than you do if you’re on two legs.

He still adds dedicated frontal plane work, lateral squats, slide board, and lateral sled drags, plus anti-rotation, anti-extension, and anti-flexion core training, which he sees as essential for the cutting sports where groin and hip injuries pile up. The single leg lifts simply do a lot of that multiplanar work for free, because the body has to control the diagonal and lateral subsystems to keep from twisting out of the bottom.

Beyond the weight room: lateral speed and movement quality

MBSC organizes movement prep into linear and lateral days, and Carr treats change of direction as a teachable skill, not just an output. The detail he hammers is shin angle.

You see a lot of athletes who try to change directions and their body’s going one way, but their shins are pointing the other way. That’s how you get people injured, and you’re going to get beat on the field.

He teaches a basic crossover and stick, then crossover to sprint, then carries that lateral acceleration into conditioning shuttles so the mechanics hold up under fatigue. His movement prep staples, slow crawling and get-ups, do double duty, building shoulder and core stability while exposing where an athlete falls apart once you remove speed. One of his favorite cues is to balance a light object on an athlete’s low back during a crawl.

You’ve got to keep that on your back through the whole 10-yard crawl. That really slows them down, because the goal becomes to keep their hips still.

Frequently asked questions

Why train single leg instead of double leg?
Because sport happens on one leg. Carr trains bilateral lifts as a foundation, but argues single leg exercises better match how athletes actually move, build lateral hip stability, and let you get a strong training effect with less spinal and systemic load.

What are the best single leg exercises for athletes?
Carr’s core menu is the split squat, the rear foot elevated split squat, the single leg squat to a box, and the single leg deadlift. He progresses athletes through them in that order, earning depth and hip control before adding load.

What is the single leg deadlift good for?
It builds the standing hip and glute and trains the lateral hip stability that runners and field athletes often lack. Carr coaches it with a cross-reaching cue so athletes square the hips and sit into the hip instead of rotating open.

Trap bar deadlift versus barbell: which is better for athletes?
For anyone who is not a competitive powerlifter, Carr favors the trap bar. He argues you lose nothing in the movement, it is easier to coach safely across a big group, and it spares the low back compared with a straight bar pulled from the shins.

How do you progress single leg training?
Start with a loaded split squat for a few weeks, move to the rear foot elevated split squat, then to a single leg squat to a box, lowering the box over time. Use a depth marker, avoid valgus and bottoming out, and add load only once the pattern is clean.

About the authors

Kevin Carr is a strength and conditioning coach at Mike Boyle Strength and Conditioning and co-owner of Movement As Medicine, a manual therapy and movement clinic based there. A licensed massage therapist and a lead instructor for the Certified Functional Strength Coach (CFSC) program, he works with athletes from US Olympians to general population clients.

Joel Smith is the host of the Just Fly Performance Podcast and the founder of Just Fly Sports, a former collegiate strength and track and field coach who focuses on speed, power, and athletic development. Listen to the full episode with Kevin Carr on Just Fly Sports.