If you're coming off a knee injury, have had a knee injury in the past, or are just hoping to avoid a knee injury, single-leg work should have a place in your training program.
If you didn't pick up on it, that's my sneaky way of saying that everyone should be doing single-leg work in some capacity. And if you've never had a knee injury, consider yourself lucky – and you should do what you can to keep it that way.
I try to avoid making generalizations or sweeping statements about what everyone should do because we're all different and have different goals. But in the case of single-leg work, I'll make an exception. It's just that important, and everyone can benefit from it.
Single-leg work may be especially important in the rehabilitation and/or prevention of knee problems. Research has shown a strong correlation between knee pain and weak hips. One study showed that subjects with patellofemoral pain exhibited 26% less hip abduction strength and 36% less hip external rotation strength than their pain-free counterparts (Ireland, et. al).
Similarly, another study revealed that knee-pain sufferers exhibited weakness in the hip abductors, extensors, and external rotators that manifested in excessive hip adduction, internal rotation, and knee valgus during functional activities (Mascal et. al),
A third study noted that in subjects with only one painful knee, the strength of the gluteus medius and maximus muscles were significantly less on the side of the painful knee as compared to the side without pain (Rowe, et. al).
With that in mind, the goal then becomes to strengthen the hip abductors and external rotators. And that's exactly what we're doing with single-leg work, because the glutes have to kick into overdrive to literally keep the femur in line against unwanted motion in the frontal and transverse planes.
Furthermore, it also helps iron out any imbalances between legs, which will likely be pretty severe after an injury.
To that, here's a picture of my legs just one day after knee surgery (note the awesome purple hospital socks). It looks like my VMO just packed up and left.
Here's the catch – as great as the idea of single-leg work can be for helping knee issues, many of the common single-leg exercises can actually wreak havoc on your knees if you're not careful, especially if you're fresh off a recent injury.
As I'm just a few months out from my knee surgery, I've been forced to tweak some of my favorite single leg standbys to be more knee-friendly. Here's what I've come up with.
1. One-Leg Squat/TKE Combo
I've written extensively about the single-leg squat and consider it to be about the best exercise for building functional stability in the hip and knee stabilizers. It's also a good choice for building up the quads.
If you're dealing with patellofemoral pain, however, it isn't going to be your first choice as it can be unduly stressful on the knee joint, especially in the bottom position.
See the pic to the left.
It's too valuable an exercise to abandon completely though, so I made a few modifications to take some stress off the knees so I could still reap the benefits without causing pain.
Find a box or bench about 16-20 inches high (most standard weight benches will do) and position it a few feet away from a power rack.
Stand on the edge of the box such that one leg is dangling off the side. Affix a small band behind the knee of the leg on the box and attach the other end to the post in front of you so that the band is parallel to the floor.
From there, squat down just as you would for a regular one-leg squat, only instead of reaching the free leg out in front, reach it straight down or even slightly behind you.
This video clip should help clarify.
The addition of the band forces you to sit back into the movement to counteract the forces pulling you forward, thereby increasing the involvement of the hamstrings and glutes. It also allows you to keep a more vertical shin, which dramatically decreases patellofemoral joint stress.
As you approach the top portion of the rep, it shifts from a hip dominant movement pattern into more of a quad dominant terminal knee extension (TKE), giving you the best of both worlds.
There are a few important execution cues to remember.
• Pick a box height that allows you to get as large a range of motion as possible while still being able to touch your non-working leg to the floor at the bottom of the rep. You'll want to end each set on the eccentric lowering phase to avoid having to jump down off the box.
• Hold small dumbbells (5-10 pounds) in each hand to serve as a counterbalance. As you squat down, raise the dumbbells to at least shoulder height and slightly higher if you find yourself struggling to keep an upright torso.
• The tension on the band should be enough that you feel a slight pulling sensation during all phases of the rep, but not so strong that it jerks you off the box. If it's so taut that it feels sketchy to get into position to start the set, either use a lighter band or move the box closer to the rack.
• Keep the non-working leg completely straight with the ankle dorsi-flexed to avoid the urge to cheat and push off at the bottom. Use the leg merely as a depth gauge to ensure you've gone all the way down.
• Although the top portion of the exercise is called a terminal knee extension, you still want to get full hip extension. As such, make sure to stand up completely and squeeze your glutes as you complete each rep.
• If you're unable to do the exercise through a full range of motion, start with a shorter box. I would call this a step-down as opposed to a one-leg squat, but the terminology doesn't really matter. It's essentially the same exercise.
Once you can complete 4 sets of 8-10 reps with good form, gradually increase the box height until the top of the femur is parallel to the floor at the bottom.
2. One-Leg Trap Bar Deadlifts
This one is hard to classify because it's really a hybrid.
It's a mix between a trap bar deadlift, a single-leg squat, and a single-leg deadlift, with a hint of skater squat (or is it a shrimp squat?) thrown in for good measure. How's that?
Now that your head's spinning, here's a video:
You could make a case for this being both hip dominant and/or knee dominant. It's certainly more knee-dominant than a single-leg deadlift, but it's also more hip dominant (and more knee-friendly) than a single-leg squat.
At the end of the day, if it's a good exercise, who cares how it's classified?
All the same form cues that apply for a regular trap bar deadlift apply here: flat back, chest up, push through the heel, squeeze the glutes at the top, etc.
It may not look like much, but it's surprisingly difficult, especially if you pause after each rep (recommended).
If it's too challenging at first, start with split stance trap deadlifts.
The key is to put as much weight as possible on the working leg and use the non-working leg solely to provide a small degree of stability. This could be used as a standalone exercise, but I prefer to use it as a progression to work towards the single-leg variation.
3. "Bottoms Up" Bulgarian Split Squats
This isn't a new exercise at all. It's actually a great way to teach Bulgarian split squats to beginners, so it's more a matter of going back to the basics.
"Bottoms up" just means that you start from the bottom position rather than the typical "top down" approach.
The starting position is extremely important. You want to begin in a position where the shin of the front leg is perpendicular to the floor and the knee of the rear leg is slightly behind the hips.
If you're too far from the bench, it'll create an uncomfortably intense stretch in the hip flexor of the rear leg, but if you're too close, it can cause undue stress on the knee of the front leg.
In people with healthy knees, having the knee travel over the toes isn't a concern if the goal is to target the quads. But for folks with knee pain, it's best to keep a more vertical shin angle to shift stress off of the knee and onto the hips.
Starting each rep from a dead stop ensures that you're set up properly from the start and keeps your form honest.
It also makes the exercise harder, meaning you'll need to use significantly less weight. Any time you're training around pain, less weight is a good thing because it means less stress on the joints. When training around injuries, I always shoot to make an exercise as hard as I can so I can use as little weight as possible and still get the desired training effect.
Don't get me wrong, I'm all about progressive overload and getting strong, but I'm always on the lookout for ways to get more out of less loading.
It may not be the best philosophy for your ego, but I'd rather have a hurt ego than hurt joints.
4. Lateral Band Walks
If you'd told me a few years ago that I'd now be doing lateral band walks before every lower body workout – much less writing about them in an article – I'd have tried to punch my future self in the face.
I used to think all that foo-foo "pre-hab" stuff was a waste of time and anyone that did it was soft. Alas, two knee surgeries later, I guess I've gotten soft, too.
I only wish I'd "gone soft" a couple years ago. Since making lateral band walks a staple in my routine, my knees have felt a whole lot better and my single-leg training has improved as well.
I was skeptical at first that they'd make much of a difference, but after some experimentation I've noticed that on days I do them before my single-leg exercises, I really do feel more stable than when I skip them.
And really, they only take about a minute to complete anyway, and they certainly can't hurt, so you might as well throw them in.
Most of the time you see these done, the bands are placed around the feet or the lower leg. That's an acceptable way to do them and that's how I teach them most of the time. But for people with knee pain, it helps to place the bands on the femurs directly above the knees to reduce lateral shearing on the knee joints.
I like to do about 2 sets of 25 steps in each direction directly before my first single-leg exercise. This isn't meant to be a strength exercise, but rather a means to activate and engage the deep stabilizers in the hips to help you get more out of your actual workout later on.
It shouldn't be too hard, but if you're doing them correctly, you'll feel it in the sides of your hips (i.e., glute medius).
Knee pain sucks, but if you're smart with your training, it doesn't have to stop you dead in your tracks. Hopefully I've given you some ideas to help you beat the knee injury blues and get you moving in the right direction.
Ireland, Mary L., John D. Wilson, Bryon T. Ballantyne, and Irene McClay Davis. "Hip strength in females with and without patellofemoral pain." Journal of Orthopaedic and Sports Physical Therapy (JOSPT). 2003, Volume: 33, Issue: 11, pp. 671-676.
Catherine Mascal, Robert Landel, and Christopher Powers. "Management of patellofemoral pain targeting hip, pelvis, and trunk muscle function: 2 case reports." Journal of Orthopedic and Sports Physical Therapy (JOSPT). 2003, Volume. 33, Issue. 11, pp. 647-660.
Rowe, Jennifer. Lisa Shafer, Kathryn Kelley, Nicole West, Terre Dunning, Robert Smith, and Douglas J. Mattson. "Hip strength and knee pain in females." North American Journal of Physical Therapy. 2007, August; 2(3), pp. 164–169.