There are many corrective exercise experts who extol the virtues of the overhead squat as an assessment of functional and healthy movement. For example, the overhead squat is one of several moves that comprise the popular Functional Movement Screen developed by Gray Cook. The overhead squat ("OHS") is certainly an interesting movement. To do it, you squat all the way down while keeping the feet flat on the ground and supporting a bar directly overhead. So you are basically combining a full squat with an overhead reach.
There are many articles on the internet that set forth the proper form for the OHS, and also identify various common faults. Many of these claim that a specific defect in some aspect of the OHS reveals a general functional problem. For example, if some body part off goes off course in one direction or another, this is interpreted as weakness in one muscle, or tightness in another, or an inability to perform some fundamental movement pattern. Corrective exercises are often prescribed to correct the errors, on the assumption that this will lead to an improvement in general movement skill.
I am open to the idea that a skilled trainer can learn something about a client's movement patterns by watching him perform an overhead squat. But this would also be true for a wide variety of other movements. Which raises the question: is there anything especially useful about using the overhead squat as an assessment tool? It may have some virtues, but in my opinion it also has some drawbacks that I will discuss below.
Most people will never perform an OHS until a trainer tells them to do one. Therefore, if you watch someone perform an OHS and rate their relative performance, a good percentage of your rating is a simple reflection of how many times they have practiced the movement in the past.
When I asked Eric Cobb (the creator of Z-Health) his opinion of using the OHS as an assessment of general movement ability, he said that's like using a tennis serve to test coordination. Well said. Of course it would not make any sense to look at a client's' tennis serve and then start drawing conclusions about their general function and the relative tightness and weakness of particular muscle groups. Although the serve could be used as an assessment of specific and specialized skills, it would not be a fair test of fundamental movement patterns. The OHS is certainly more simple than a tennis serve, but it should be noted that it is also a very specific skill that does not come naturally.
It ain't natural
Unlike squatting or reaching overhead, squatting while reaching overhead is not something that humans are designed to do without specific practice.
The purpose of squatting down is to get the pelvis, hands and eyes closer to the ground, to inspect something, pick something up, or just rest. This is a very basic human function built on the primal pattern of full body flexion. Toddlers don't need to be taught how to squat, and they all squat perfectly before age two.
Reaching overhead is also a very primal movement which involves almost the exact opposite pattern. In this case, the pattern is extension - all the extensors in the body shorten and the legs straighten to create length.
Is there any real life functional purpose to squatting down to the ground and reaching up at the same time? Outside of the gym, no. The movements of squatting and reaching up work at cross purposes to each other, and I can't think of any real world movement that would combine them. Holding up a low ceiling? This is simply not a movement that comes up in real life.
And as such, we are not well designed to do it in the absence of specific practice. The key to proper execution of the OHS is maintaining chest extension while squatting. The reason this is difficult is that activation of the squatting pattern in the lower body will mechanically and neurologically encourage the upper back and shoulders to round forward. Reaching overhead requires the opposite pattern in the upper body, which is easy while standing (big surprise) but takes practice to learn while in a squat.
I should emphasize that none of this means that the OHS is a bad exercise or that it can't be performed safely and effectively. But I do think it suggests that the OHS is a poor way to assess someone's general movement patterns. Chances are, the faults you find in the OHS are due more to a lack of specific skills as opposed to a lack of good general movement patterns.
Of course, a perceptive trainer will pull relevant information from any movement a client makes, including the OHS. But the movements which are more likely to be revealing are the ones that clients have done hundreds of thousands of times and are truly ingrained, such as walking, breathing, getting up and down from a chair, etc. These movements may not allow us to create simple templates or algorithms to match specific faults to specific corrections, but let's face it, the body is more complicated than that anyway.
What do you think? Have you found a good use for the OHS? Let me know in the comments.