The Bilateral Deficit
Let’s start by answering the question, what is the bilateral deficit? The bilateral deficit is the thought that one can produce more force, and power for that matter, on one leg rather than two, when both of the single leg totals are combined. So if that is the case everyone should drop bilateral movements and go with its unilateral counterpart, right? Before we make that leap let’s review the pros and cons of both.
Although you can discuss the bilateral deficit for both the upper and lower body I will be sticking with the lower body and using the squat for comparison. This is the most heavily debated area of the bilateral deficit so I see no reason to stray from the topic.
The bilateral deficit is now an additional part of an argument that has been being made for using unilateral squat variations long before it was even a hotly debated topic in the strength and conditioning world.
Below is my review of both squat variations.
-There is a greater amount of force produced during the movement with both legs pushing equally. Along with a greater amount of force being produced a greater anabolic hormonal response will take place.
-Having both legs working at the same time does not limit one’s ability to produce an equal amount of force on the second leg as with the unilateral squat variation.
-The unilateral squat, and for this discussion, the rear foot elevated split squat (RFESS) is the movement of choice when selecting an exercise from this category. The RFESS avoids the pelvis from going into a posterior tilt. This means your hips do not disappear underneath you. This will protect the vertebrae of the lumbar spine from any flexion taking place. This is my #1 reason for choosing this movement over the bilateral squat if I am only going to choose one version.
- The words “sport specific” gets tossed around like political correctness nowadays, but nonetheless it is worth bringing up. Is a unilateral squat more sport specific than a bilateral squat? That is certainly a possibly, although I think the term is grossly overused and should only be used when mastery of the basics takes place for any athlete. With that being said a split squat is one of the basics that an athlete should master. So is it more sport specific or not? I think if you polled 100 strength and conditioning coaches it would favor saying it is sport specific, maybe 70/30.
-Athletes, especially younger athletes and if we want to get even more specific, younger, male athletes struggle immensely with the bilateral squat. I am not referring to loading weight on the barbell, but a body weight squat. The athlete lacks the mobility and stability to perform a body weight squat in most cases. This is likely due to a number of factors, but a huge one being that puberty is taking place and growth is making things “tight”. At this time the split squat is a much better option.
So at the end of the day it is not necessarily the bilateral deficit that is going to make me choose a bilateral or unilateral squat pattern, but the athlete’s ability to do either movement. I personally include both variations for my athletes based on what I have previously mentioned.
What squat variations are you having your athletes perform?
8/20/2018 08:05:44 am
For my MSc, I researched the bilateral deficit (BLD) with 30 highly-trained participants. In short, it appears that if you train bilaterally, you will be stronger bilaterally. In contrast, if you train unilaterally, you will be stronger unilaterally. I am actually finishing a book on this topic, but for my Ph.D., I am studying high-intensity-interval training. However, I did keep up with the latest BLD research
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