Balance! The first thing you probably think of trying to stand on one leg with the other bottom of the opposite foot resting on the medial portion of your knee. That’s right. The stork stance. The next is trying to move across a balance beam at lightning speed as a 10-year old child, and then making the most incredible dismount EVER! Next thing you know, you look like Mary Katherine Gallagher, screeching out “Superstar” at the end of your balance beam routine.
 
Ultimately, we are not going to try to become the most popular private school student ever, and we definitely do not need to be standing like a wild bird for some reason. We are talking about balance from right-to-left or left-to-right, otherwise known as asymmetry.
 
According to Brown et al. (2017), asymmetry is the interlimb differences prevalent in an array of important metrics and potentially increase the risk of injury as the strong limb begins to work at the upper limit of its physical capacity and the weak limb is unable to endure such effort. What this is saying in another perspective is that in the measurement of different limbs, there is more of a risk if the stronger limb is drastically different than the weaker limb in overall strength. An example of this is to go to your local big box gym, hang out with all the “bruhs” and begin doing some single-arm, dumbbell bicep curls.
 
Instead of reaching a specific point of the same weight with both hands, you would continue to complete a single rep until you achieved the highest weight you could for both hands separately, regardless if one weight lifted is higher than the other.
 
Now I know this sounds absolutely ridiculous because weightlifters do not complete bicep curls in the squat rack, but it does serve a point about trying to see how one side is stronger than the other. Obviously, bicep curls are just a really poor example, but you get the point. Make the decision to lift one side of the body and then complete the lift for the other side. The question then becomes, “What do these weights lifted per side mean, and why does this comparison even matter?”
 
Instead of the curls, let us use two lifts more relevant to weightlifters: the single-arm push press and the barbell split squat. These are common motions than can be completed with equipment that is readily available at local gyms and at weightlifting facilities. Also, they have carryover to movement patterns a weightlifter would complete. These lifts will be two of many lifts that you could compare, but let us use these as the prime examples.
 
Now, to put this in perspective, let us have Lifter A and Lifter B. They have been training at your facility for a while and have been competing regionally, looking to potentially move to the national stage if they can improve from their current status. Based on visual inspection, you feel that there may be some imbalance the lifter has, so you decide to take matters into your own hands and throw an assessment at them on a Saturday morning instead of their normal lifting routine. Lifter A and Lifter B showed the following scores for their lifts respectively: A – left arm – 75 lbs., right arm – 85 lbs., left leg 90 kg, right leg, 97 kg; B – left arm – 95 lbs., right arm – 100 lbs., left leg – 107 kg, and right leg – 113 kg.
 
There has been some research on a system of measurement that has shown positive changes when put into assessment and then showing improvement after training has taken place. Maximum voluntary contraction and muscular torque have been improved greatly during this testing in multiple situations. Using the Limb Symmetry Index (LSI) scoring method is easy and really is not some algorithm that is challenging to following. Very easily put, the equation is as follows:
 
 
 
Lifter A would have two scores: Upper body = 88.23%, Lower body = 92.78%. Lifter B has two scores as well: Upper body = 95%, Lower body = 94.69%. What this truly tells us is that Lifter A has a 11.77% and 7.22% imbalance throughout their body. Lifter B has a 5% and 5.31% imbalance throughout their body. So, this answers the first question. It means that the numbers show the percent difference lifted between sides for both the upper and lower body, but there is more to this than meets the eye. You would also want to assess the competition lifts as well to have a baseline of all assessment numbers. This means that both lifters should be assessed in the Snatch and Clean & Jerk, as well as a Squat variation.
 
We can then decipher the second question. What does the comparison mean? In current research, a percentage difference that is between 10-15% can begin to show signs of diminished maximal power output. Anything above 15%, lifters and coaches must start to think about how to minimize the side to side difference so power output can be optimized for them, but also how can it be decreased to lower injury risk. With our examples, we can see that Lifter A is showing signs of increased diminishment of power and potential injury risk for their upper body, but not with their lower body. Lifter B is in a common area of dominant to non-dominant because we understand that all humans are never going to be completely symmetrical (both sides are equal in strength) due to one side being used more than the other.
 
Great! We have some assessment data that can help our lifters. But how do we put these into practice, or how will it be applied? This question is the most challenging because asymmetry may be smaller like Lifter B, and slightly larger like Lifter A for all your lifters. In all honesty, we could actually have lifters who could go over the 15% danger zone and can still lift very well, but that does not mean they are in a healthy state to move for general movement pattern. It also could indicate they are more prone to have a non-contact/non-lifting injury present itself. This means we must figure out how to potentially help Lifter A some more because there may be some potential missing from their lifting, but also not give up different unilateral training modalities for Lifter B.
 
Currently in my dissertation work, we are looking at how unilateral work mixed into bilateral work will help weightlifters to maintain symmetry versus solely bilateral work. In most of the current research, unilateral work is showing to help asymmetries shrink in size to help the lifter be more well-rounded versus favoring one side.
 
While lifting unilaterally, we may start to see our lifters not have dramatic weight shifts or uneven limb distributions while going from first pull to recovery. Does it mean it will clear up all the way? No, and that could be due to years of imbalance that lead to distorted movement patterns of the joints themselves compensating for such long periods of time. Ultimately, we want our athletes to be as symmetrical as possible to keep strength and power as high as possible and diminish injury risk, because athlete health is imperative.
 
In addition to completing the main competition lifts, pulls, squats, presses, etc. using barbells and bilaterally technique, we can complete lifts in unilateral formats along with other motions that will still enhance athletes. According to Zult and colleagues (2016), there is something termed cross education which is “the phenomenon by which strength or skill development achieved during the training of a single limb is transferred to the contralateral untrained limb.” What this is referring to is although we may be training with a single-limb during a specific set/reps/etc., the body recognizes there is a stimulus and can potentially transfer that strength to the other limb, which would enhance that side as well as the lifting side. Through the use of unilateral training, this cross education can occur when using single-limb work at a moderate to moderately-high training intensity. This then leads to the best unilateral motions that will help an athlete to diminish asymmetries or to maintain a more symmetrical state of their system.
 
If you were to peruse the Catalyst Athletics exercise video archive website for unilateral lifting motions, you would find exercises such as: Single-Leg Dumbbell RDLs, Bulgarian Split Squats (and other variations of split squats), Lateral Lunges (and all other lunge variations, Rear Leg Elevated (RLE) Good Mornings, RLE Stiff-Legged Deadlifts, Single-Arm Push Press (and any other single-arm press), Single-Arm Clean & Jerks and Snatches, and also the more convention “Beach Body” style lifts that can still have direct carryover to any weightlifter.
 
This is obviously a very small list and by no means exhaustive, but understand that the main factor here is developing a proper unilateral plan that coordinates well with the bilateral motions of the competition lifts and their accessories. As coaches and athletes, we do not want to overwhelm the complete system during a training session, but rather provide enough stimuli to minimize the increase of asymmetry and still provide some strengthening accessories to the working muscles.
 
We all know that we have a dominant side to our system. Whether you are right- or left-handed, dominant in strength on your right or left side, or neither, you will still have one side that may be slightly different than the other. Do not be afraid to assess! As coaches, you should not hesitate to assess or reassess because it can give vital feedback to improvements of diminishing asymmetries.
 
Lastly, make sure to check whether diminished asymmetries are actually showing improvements with the competition lifts because this can be one of those moments where you keep throwing everything at your programming and recovery, yet it could just be the body telling you it needs to be evened/equaled out just enough to help the whole kinetic chain move more effectively and efficiently. Weightlifters should not be afraid to go one-sided with their lifts as it will not hurt their competition lifts and diminish strength as some may fear. Good luck with this and understand that better mechanics through reduced asymmetries can have positive impact on lifters.