Unilateral vs. Bilateral Training – Is the Squat Dead?

Do you perform “functional exercise” and laugh at those working on the conventional back squat, or are you on old school weight lifter who thinks the guy doing split-squats is a sissy?

Today, we’re going to talk about unilateral exercises vs. bilateral exercises and figure out which one is the superior form of exercise.

This whole debate was ignited when a strength coach by the name of Mike Boyle came out in 2009 and declared the conventional squat to be dead. He released a video of himself speaking at some lecture or seminar, and makes an interesting argument against bilateral training and in favor of unilateral training.

The big take-home message in his video is that he claims that the back is always the “weak-link” during conventional squats, which prevents the athlete from totally developing leg strength.

I have to give him credit, because he makes a compelling case for his claim of that “the conventional squat is dead.” It takes a lot of cojones to come out and say that one of the training tools that has created strong athletes over the past few decades is obsolete – and of course, Mike Boyle has been met with some backlash, by weekend warriors, athletes,  coaches alike.

In response to an inquiry about Boyle’s statements, Mark Rippetoe (author of Starting Strength: Basic Barbell Trainingone of my favorite training books) had nothing kind to respond with. Rippetoe said this on his forum:

“The likelihood of Mike Boyle’s article causing the wholesale abandonment of the squat is exactly the same as my disapproval of the consumption of soy causing chaos in the commodities markets tomorrow morning. It is irrelevant to the fact that squats, deadlifts, cleans, presses, and bench presses make weak people strong and Coach Boyle’s program does not.

Be calm. Train as if this never happened and everything will be fine.”

Mark Rippetoe cracks me up. He’s great. Jason Ferruggia, another prominent strength coach, wrote a piece on his blog in response to Boyle’s statements. Here’s what Ferruggia said:

“I can imagine nothing worse. Guys love to squat. Most of the guys I have trained LIVE to squat. It’s a big, bad ass, fun exercise that you can pile plates on and get all fired up for with some smelling salts and head butts and just get fucking nuts. When guys squat heavy weights they excited. And when they do it all off-season they develop a chip on their shoulder and a “fuck you” attitude that makes them a force when they walk into camp.

This ain’t happening with lunges.”

Well, you can tell people aren’t happy with Mike Boyle, and the debates rages on. Is the squat really dead? Which kind of training is better? Well, let’s see what unilateral and bilateral exercises offer us, compare them, and see which are better suited for certain situations.

Which Is Better: Unilateral Or Bilateral Training?

With unilateral exercises (such as the Bulgarian split-squat or the lunge), you are getting these advantages:

  • The total load on the spine is reduced, because the weight is cut down roughly by half.
  • The split-stance used in unilateral exercises is more similar to the athletic stance. One foot pushes off the ground, and the other lands on the ground.
  • Technically, one can move more weight PER LEG compared to bilateral exercises (as mentioned in Boyle’s video).
  • Stabilizing muscles are engaged more.

Now, here are the advantages of bilateral exercises (such as back squats):

  • The absolute greatest amount of weight can be used, because the entire body is used, not just one leg.
  • There is less importance for balance and stabilizer muscles, again allowing more weight to be used.
  • Exercises, such as the squat and deadlift, are tried-and-true methods that have created powerful athletes, huge bodybuilders, and all-around strong people for years and years.

Now you can see that BOTH have their own benefits. It is certainly hard to choose one over the other. We do have to look at various aspects of this debate, however, before we even decide which type of training is better.

Carry-Over Between Unilateral And Bilateral Exercises Is Limited

I’d first like to address Mike Boyle’s claim that his athletes can not conventional squat as well as they can split-squat. As with any exercise, when you practice it and train it for weeks and months, your body will adapt to that particular movement and load. People use these exercises to get stronger or faster on the field, but what a particular exercise will have 100% carry-over to is to the same exercise. Basically, back squatting will make you better at back squatting, etc. Yes, these a single exercise will carry-over into other tasks and exercises into varying degrees, but never at 100%.

With that said, the I think reason why Boyle’s athletes couldn’t perform the conventional squat well is because they didn’t train the conventional squat. How can you expect someone to do a particular task well when they’ve never spent time mastering it? If his athletes had backs that were used to loads with unilateral exercises (e.g., what is half the load of a bilateral exercise), had could they possibly handle what is the same load per leg, but twice that their spine’s are adapted to?

The same situation applies vice versa. If you’re used to doing bilateral movements, you’re stabilizers and ability to balance will be less developed. So, if an athlete (who only trains the conventional squat) tries to do half of his squatting weight for a split-squat or lunge, this athlete would probably not be able to perform it. This is despite the fact the weight per leg is the same for both unilateral and bilateral movements.

So, I believe Boyle’s point doesn’t hold much ground.

Bilateral Exercises Allow For The Greatest Strength

Depending on your definition of “strength”, bilateral movements  may or may not be the winner here. If you define it as “a person’s ability to use the ENTIRE body to move the greatest amount of weight possible”, then bilateral exercises allow for the greatest strength. With that said, unilateral exercises will leave you unable to perform traditional measures of strength, AKA bilateral exercises such as the squat. If you can perform a 200 lb lunge per leg, and that is the only leg exercise you use, you cannot in turn perform a 400 lb squat. Thus, you “ability to use the ENTIRE body to move the greatest amount of weight possible”, AKA strength, is limited.

Think of it like this. As you squat, your entire body is used – no questions asked. That is the movement you are becoming an expert at, and every muscle, joint, and bone is being developed accordingly. As you lunge, you are only using one leg at a time. That is the movement you are teaching your body – how to use the strength of one leg at a time. Additionally, your are sparing the spine from load. So, with a unilateral movement, you are not learning how to use the strength of your entire body, and your not fully developing the strength of your spine.

By choosing unilateral exercises over bilateral exercises, your whole-body strength will suffer – and by reducing the load on your spine, you are reducing the risk of back injury, but at the cost of a weaker back. Remember, load = adaptation.

Unilateral vs bilateral exercises.Yay, I’m so strong!

Do All Athletes Need Whole-Body Strength?

While we know that bilateral exercises develop the entire body’s strength more effectively, what needs to be determined is whether or not the athlete or client NEEDS this absolute strength. Who’s going to need to have a stupid-crazy-strong spine, a football player or a basketball player? Who’s the one constantly getting tackled and pounded in his torso?

This video might give you a hint.

If I’m a football coach, you better bet my linemen, receivers, and quarterbacks are do heavy back squats. When you’ve got 400+ lbs on your back, you better bet that the boney vertebrae and spinal disks are getting stronger and more dense. I see it as a higher risk, higher reward exercise that these athletes do to maximize their toughness and ability to take a hit. But is all of this necessary for a limited-contact athlete, like a basketball player?

Sure, the guys in the NBA occasionally crash into each other, fall or get into scuffles, but it’s nowhere NEAR the level of impact that guys in the NFL experience. So why spend time on riskier exercises, such as heavy back squats? I don’t think they need as much back strength. Leg strength, which I’m sure is important for basketball players, can still be achieved with unilateral exercises.

This also applies to people who aren’t athletes. Are you in a physically-demanding job (e.g., military, EMT, fireman) that requires all-around toughness, or do you have a desk job that doesn’t have physical requirements? Understanding your needs and demands will help you decide whether you need to do bilateral training for whole-body strength, or can just give your back a break and stick to unilateral training.

Unilateral Exercises Have Other Benefits

For those with back injuries, the split-squat is an awesome progression to be used when trying to work one’s way back up to the regular back squat, simply because the load on the spine is cut in half. Also, for those with seriously-debilitating back injuries, they may only be able to do unilateral exercises for a long time (or, forever). Sure, whole-body strength is achieved bilaterally, but for those who are crippled or seriously damaged, unilaterally movements are much better than nothing. Not everyone can be a football lineman. With that said, unilateral movements are a great rehabilitation tool or a replacement for the seriously injured.

Like I said before, stabilization and balance is emphasized more during single-leg training, which is particularly useful, for athletes and others, in its own right. Balance is a skill of its own, and allowing stabilizers to become weak can result in various injuries (like rotator cuff impingement or patella-tracking disorder).

Not everything we do in life is performed with both feet at the same time. Most natural movements – running, tackling, crawling, climbing, etc, – involve one leg driving driving the body, while the other plants and follows-up with driving the body, and so on. So, there seems to be an added importance for being able to do things unilaterally, one leg at a time.

Rocky, mossy terrain.
I’ve got a feeling heavy back squats won’t help you keep your balance on this rocky terrain.

So, Which Type Of Training Is Better?

So, in the end, both unilateral training and bilateral training are important. It would make sense to use both in training program for athletes, as strength, balance, and stabilization are all important for performance on the field. It’s up to the athlete, coach, trainee, or whomever to figure out what goals need to be met and which kind of exercises will help reach those goals.

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One Comment

  1. Photo Credits
    Strongman squat. Artur Andrzej. commons.wikimedia.com
    Lunge. Myles Stepp. commons.wikipedia.com
    Rocky terrain. Author: Joshua Mayer. flickr.com

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