The Beginner’s Guide to Strength Training (Part 7 of 30): Single vs Double

All strength coaches want stronger and healthier athletes — how they get there, however, differs.

There are all types. Some love powerlifts; others don’t. Some love Olympic lifts; others avoid them. And some use newer tools and equipment, while others stick to good-ol’ barbells and dumbbells.

As much as I hate cliches, there really is “more than one way to skin a cat.” With all the options available nowadays, there’s no right or wrong way to train — as long as there’s a theory and an emphasis on safety, clients and athletes can achieve great results.

In this article, I’ll explain another big debate within the strength and conditioning community: should we focus on single-leg or double-leg exercises?

Now, using single-leg (unilateral) exercises aren’t new. But using only single-leg exercises is. Within the last decade, numerous elite strength coaches have shifted in favor of one-leg over two — and since they conflict with strength and conditioning traditions, they’ve also fielded criticism.

Yet the more clients I train, the more I like unilateral training. Why? Well, let’s discuss the differences:

What Is Bilateral?

In bilateral (double-leg) exercises, you spread resistance across both legs; both feet are on the ground – or a machine – at the same time and do equal amounts of work.

These have long been the centerpiece for strength and conditioning programs at all levels. Take the back squat and deadlift, for example: countless schools and teams teach their athletes these for great strength and power development.

Benefits

• More strength

  To develop strong and powerful athletes, there’s no substitue for heavy bilateral leg exercises: front squats, back squats, deadlifts, and Romanian deadlifts are all great for building muscle. And because you can push and pull more weight with double-leg exercises, you’ll benefit from a higher stimulus for muscle growth and hormones too.

  Also, there’s more stability with two feet on the ground than just one. Thus, we do more work with our “prime movers” – powerful muscles like the glutes, hamstrings, and quads – because our stabilizers don’t do as much.

• More power

  Power = Strength / Time

  The more strength you display in less time, the more powerful you are. Thus, bilateral exercises often beat single-leg exercises for power development. A power snatch, for example, generates a lot more power than any explosive single-leg exercise.

• Develop good movement patterns

  Teaching someone a proper squat or deadlift has amazing benefits. They’ll move better because their muscles will fire in the correct sequence, they’ll improve coordination and proprioception, and they’ll increase their mobility. A good deadlift also trains a person to maintain a neutral spine and load their hips safely while bending forward.

What Is Unilateral?

With a “unilateral” or single-leg exercise, almost all of the load is on just one leg. These exercises also divide the body into left and right sides because you’re only training one leg at a time.

Two examples of unilateral exercises are the split squat and step up: in both, one leg is doing most of work and you train each leg separately.

Benefits

• Less weight on your body

  You can’t lift as much with one leg as you can with two.

  More weight builds more muscle, but it also increases stress on your joints, ligaments, and tendons. What if those areas weren’t healthy? If you had disc issues, for example, compressing your spine with heavy weights could worsen those problems.

  But you can still work your legs hard without heavy weights — by manipulating range-of-motion, angles, and your base-of-support, you can make almost any unilateral exercise pretty damn difficult.

  I’ve had clients who – from previous injuries – feared compressive force. “Whenever I hold or carry heavy weights, my back starts hurting,” they’d say. With bodyweight single-leg exercises, however, they still managed to build bigger and stronger legs without any pain.

• Less asymmetries

  One of your legs may be stronger than the other.

  Imagine, for example, that you can do 12 single-leg squats on the right leg, but only 4 on the left. (I’ve actually seen imbalances like this before.) Lets also imagine that you only used bilateral exercises — could you fix that asymmetry?

  Maybe.

  If you tried using more force with the weaker leg during a back squat, you might be able to fix it. But wouldn’t it be easier just to train unilaterally until both legs had equal strength? Instead of putting uneven stress on your muscles and joints with a back squat, you could simply train the weak side directly.

• More stability

  All single-leg exercises target the transverse (rotational) plane. Let’s look at the split squat: if the movement travels up-and-down and front-to-back, how could it be transverse?

  Because the body must resist against rotation — even though you aren’t twisting, those muscles are still working.

  Also, unilateral leg exercises activate and strengthen the smaller, stabilizer muscles of your lower body like the glute medius, tensor fascia latae (TFL), adductor, and quadratus lumborum. This improves movement quality and guards against injury.

Which Should You Do?

Both, if possible.

If you’re injury-free and move well, blending both bilateral and unilateral exercises will help you reach your goals.

If you have no injuries and have clean movement patterns, I would prioritize bilateral training – such as squats and deadlifts – to help you build a solid level of strength. (For almost any fitness goal, you’d benefit just from adding a few pounds of lean muscle mass.) Each workout should also include unilateral training to further build leg strength while fixing asymmetries and developing stability.

But how many people are pain-free and have great mobility? Not many.

What about a person with low back pain or shitty movement patterns?

I’d focus on single-leg exercises.

Don’t burn me at the stake just yet. I still include some double-leg exercises to improve their movements. But the main focus is unilateral training because I can get my clients pretty strong without the risks.

If a client looks awful when squatting (which is common), we can correct that. But if they only train for 1 hour, 2x/week, how long will it take to develop a squat pattern that’s ready to handle weight? Two weeks? Three weeks? Over a month? And what about all their other needs?

Since clients learn the single-leg squat quickly, I start them there to build strength. In the meantime, I’ll still give them plenty of mobility exercises and squat corrections — it’ll just come after. As a great coach taught me, “use a safe range-of-motion and work them hard; don’t get too ‘corrective.'”

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On the next installment, I’ll discuss what could be the most-important part to a great workout: the warmup. Here’s some homework (sorry): think about how you currently warmup. What muscles are you targeting? What’s your goal? Is there a purpose, structure, or order? If not, there could be more to a proper warmup than you think.

Throughout this seres, I’m sure you’ll have a lot of questions, so be sure to ask using the comment section of this post. Feel free to reach out to me via Facebook and Twitter to get your question answered. See you soon!