Almost every sport requires athletes to move unilaterally – i.e. emphasizing one leg, arm or side of the body more than the other. It’s rare for any athlete to be generating motion bilaterally using both arms, legs and sides of their body equally. And when they do, it’s not for very long and usually precedes a transition back to unilateral movement. And yet in the gym there can be a temptation to focus most if not all the training we program for our athletes on bilateral exercises.

Whether it’s with the All Blacks or other teams and individual clients of various skill and experience levels, I’ve always been a big believer in training how you need to play on game day. So that they achieve maximum readiness and preparedness to perform at their very best in competition, you have to create a realistic and functional program for your athletes that pertains to real-world demands. Otherwise, what are we really doing with our time?

There are multiple reasons for making unilateral exercises an integral part of your programming, no matter what sport your athletes are competing in (or if they’re non-athletes just wanting to train more effectively), what their goals are and whether they’re used to single-sided work in the gym or not. One of the main ones is injury. If you participate in a sport for long enough, getting hurt to some degree is virtually inevitable. You don’t have to be an international rugby player or NBA pro to get banged up doing your activity of choice – just think about all those pulled hamstrings we see in rec league soccer games and twisted ankles in pickup basketball games!

As such, almost every client you work with will have some kind of injury history – varying from the occasional knock to a long list of sprains, breaks and tears. And as we know, the biggest predictive factor for future injury is a previous one (coupled with the severity of that incident). When someone gets hurt, they inevitably start to change their movement patterns and make compensations for the injury, whether that’s to work around pain, stiffness and swelling during the acute phase or to deal with the lingering effects as they make their full return to activity. The imbalanced body that naturally deemphasizes the injured side will overemphasize the other to make up for it. This tilting in the undercompensation/overcompensation see-saw may not only lead to issues with the injured muscle, joint, ligament or tendon, but also create trouble up and down the kinetic chain from the site of injury. So if someone hurts their ankle, the knee and hip can be adversely affected as well, and vice versa. While the pain resulting from injury can be localized, the biomechanical impact rarely is.

The opposite side can also be adversely affected by alterations in how we run, jump or perform any other movement skill post-injury. When a player injures their left calf, for example, they often end up tweaking their right hamstring if they’re cleared to commence sprinting too soon after the initial incident. Another common compensation-related complication occurs in clients who have one adductor or glute that’s failing to fire in synch and to the same degree as the other. This often manifests itself in the secondary issue of a groin pull on the opposite side. Sometimes it’s a case of a prime mover being required to switch its role to a stabilizer, which will then change the job descriptions of other muscles and tissues as well. The relationship between push and pull and move and stabilize can become quite fundamentally altered as the body tries to adjust to compromised function.

One of the challenges with relying solely on bilateral exercises is that they provide the illusion that both arms and legs are doing equal work. After all, it’s an even load on both sides of the bar, right? If there aren’t any visually obvious warning signs, like one end of the bar dipping down too far on a back squat or an elbow flaring out dramatically during a pull-up, then the issue may well remain hidden unless the athlete complains of pain or gets injured. When you’re training larger groups of athletes it’s difficult if not impossible to keep tabs on every individual’s movement quality throughout each exercise, set and rep. And when athletes are doing workouts away from you and the team facility, you won’t be aware of any warning signs unless they are pronounced enough for the athletes themselves to tell you about them. But as coaches, we can’t just wait until something breaks, or abdicate responsibility to another member of the training staff, such as a PT or massage therapist. Instead, we have a responsibility to be aware, make proactive decisions and step in to take corrective action before such a dramatic wake-up call occurs.

In addition to re-grooving optimal movement patterns so the athlete abandons the potentially harmful ones that they began defaulting to post-injury and tacking any accompanying mobility challenges, it’s important that we start to address the resulting issues in asymmetry and muscle activation. One of the best ways to do so is to incorporate unilateral exercises that help recalibrate the nervous and muscular-skeletal system and iron out any kinks created by injury.

Another reason for putting more stock in single-sided exercises is that most people have anatomical imbalances and asymmetry issues to some degree. I’ve been reading Mike Boyle’s recent posts and he has made the point that even the location of our organs leads to structural discrepancies between the left and right sides of our body. For example, the fact that the heart is positioned on the left of the chest cavity impacts skeletal structure, lung function and more in the trunk. It can even contribute to differences in muscle tone, which can be hidden by bilateral exercises but illuminated by athletes’ varying left/right capacity in unilateral exercises like side planks (more on this movement later). Outside of the anatomical differences that all of us are born with, there are usually individualized ones, too. Some people are born with one arm or leg longer than the other, are asymmetrical in the structure of their joints or have other hereditary left-right imbalances. While performing unilateral exercises is obviously not going to change the formation of bone or alter limb length, it can help the athlete minimize the potential negative performance impact of such anatomical imbalances.

So now that we’ve explored why you should have your athletes do unilateral exercises, how do you go about incorporating them into your daily programming? For me, it’s about keeping it simple. Like most coaches, I have several bilateral “big rocks” in the gym that allow my athletes to generate maximum strength and power in a closed torque environment, using an evenly balanced load on a longer implement such as a barbell. My go-to lifts of this type include deadlifts, back and front squats, weighted pull-ups and bench presses. To complement these, I simply make unilateral exercises the accessory work for my clients on any given day.

These often involve similar movement patterns to their bilateral counterparts, but have greater requirements for obtaining and sustaining trunk stiffness, single-limb stability and mobility, and symmetrical muscle activation. Single-sided exercises also require the client’s body to resist rotation, as well as creating different flexion and extension demands from double-sided versions. Plus, becoming more proficient in unilateral lifts feeds back into bilateral exercises as athletes enhance their competence. So if a client starts addressing some of their movement issues with step-ups and split squats, it can also increase the amount they can back squat, as well as the quality of this exercise.

Sometimes you can add in more than one unilateral load, such as by having a player do a lunge with a kettlebell or dumbbell held in a stable position overhead in just one hand. Weighted step-ups are another good use case. You could also utilize more complex exercises that require athletes to preserve integrity through the transverse plane. Get most clients to perform a Turkish get-up and you’ll usually find that it’s way harder on one side than the other, due to some kind of left-right imbalance or asymmetry.

One more way that I find unilateral exercises to be useful is in cross-education. If an athlete gets hurt on one side, it is tempting to just shut them down completely for a while until they heal. But research by the likes of Ashlee Hendy (strangely I don’t have an aversion to praising an Aussie when they’re doing good work!) have shown that training the healthy side can help preserve strength and prevent atrophy on the injured one. So if you have a player who has hurt their left pec, say, it would be beneficial to have them do single-arm dumbbell or kettlebell presses on their non-injured side as part of their rehab protocol.

Here are a few examples of how I follow bilateral exercises with unilateral ones:

1) Bilateral big rock: Squat

Unilateral accessory exercises: Split squats, step-ups, lunges, lunges with DB/KB overhead in the opposite hand

2) Bilateral big rock: Deadlift

Unilateral accessory exercises: Single-leg Romanian deadlifts (RDL), single-leg glute/ham raises if the equipment is available

3) Bilateral big rock: Weighted pull-ups

Unilateral accessory exercises: Single-arm dumbbell or kettlebell upright rows, bent-over rows, one-arm overhead vertical pulls

4) Bilateral big rock: Barbell bench press

Unilateral accessory exercises: Single-arm push-ups, overhead kettlebell presses and dumbbell bench presses

In addition to using these bilateral and unilateral combinations in the gym with my athletes, I also incorporate single-sided exercises into movement preparation for on-field practices. In the gym, the focus is often on increasing strength, speed and power with unilateral work, but here my aim is to iron out any left-right asymmetry in mobility and stability so that the players aren’t overcompensating on one side while undercompensating on the other during team practices and in games. Some of my go-to options in this setting include single-leg hops, skips and bounds to prepare for dynamic movement, and one-arm push-ups, planks and bridges to activate the trunk, shoulder girdle and back.