The Guessing Game – Box Squats Part I
By Dan Wagman, Ph.D., C.S.C.S.
THE GUESSING GAME – BOX SQUATS
Part I: Two Guesses
Like most guys and gals that got bit by the iron bug, I used to read all sorts of stuff about training. Once I came across something that seemed promising, I couldn’t wait to put it to practice in the gym, not to mention the torture I went through trying to manage the anticipation of huge gains. Of course those huge gains never happened, not until I learned about an area of scientific investigation called exercise physiology and started to apply what I learned. You see, that stuff isn’t based on guesses and conjecture. What I would like to share with you is a perfect example of why what might seem like really good training advice, when looked at from the perspective of human physiology, it couldn’t deliver as promised. My hope is that you’ll then be able to make more educated decisions about from whom to take training advice and what sort of questions to ask in your assessment of that advice.
The First Guess
It seems beyond obvious; for you to squat a ton of weight you have to be able to descend to below parallel in a controlled manner and once you hit depth you need to explode out of the hole in an effort to complete the movement. Nearly every lifter will tell you that the hardest part of the squat is blasting out of the hole. Naturally, this begs the question: might there be a method of training that’ll enhance your strength and power for getting out of the hole? Decades ago one very passionate powerlifter and coach came up with box squats for that very purpose.
The guess he made is that if you could squat down to a box that’s just the right height to break parallel, and you literally sat on it while rocking back, pausing on the box for one to five seconds or so, then blasted off it with all your might, you’d be able to increase the power you need to get out of the hole in a regular squat. This sounds really good. And so decades after the box squat idea was conceived tons of lifters still use it to increase their overall squat strength (though other purported benefits are said to exist). My guess, however, is that what seems to be such a good idea is far less than that when viewed through the lens of exercise physiology.
The Second Guess
The origin of my guess is based on the physiology of muscle contractions. Therefore, it’s really not a guess, but just humor me and let’s stay with the guessing theme.
When you squat down to depth your quad and glute muscles elongate, this is called an eccentric contraction (note that other muscles are involved, too, but addressing the entirety of functional anatomy and biomechanics is beyond the point of this article). When you reverse direction out of a deep squat, those same muscles shorten in what is termed a concentric contraction. For a very brief moment, as your muscles switch from eccentric to concentric, they contract isometrically. The linking of these contractions is referred to by some scientists as the coupling phase. Now, a fascinating thing occurs in your muscles during the eccentric phase of the squat—your muscles store elastic energy. As you reverse direction that stored elastic energy is released resulting in a powerful completion of the lift. The singular moment of switching directions is called the amortization phase and the entirety of what occurs here is often referred to as the stretch-shortening cycle. And here’s where another fascinating thing occurs; the longer the amortization phase, the more elastic energy is lost for the subsequent concentric contraction. Simply put, the longer the time you spend sitting on a box, the weaker you’d be during the ascent.
The above represents perhaps the most important amortization phase mechanism—reutilization of stored energy. Other proposed mechanisms include a stretch reflex, muscle-tendon interactions allowing muscles to remain at optimal lengths and to shorten at the best velocities, optimized muscle activation patterns, and increasing pre-force before the concentric contraction. Regardless of the mechanism(s) involved, it seems clear to me that the basics of muscle physiology deeply contradict the stated benefit of the box squat; as you sit on the box you’re increasing the amortization phase and ostensibly breaking the coupling phase, thus squandering valuable elastic energy. How could that possibly result in increased squatting abilities?
With that in mind, it’s well and good enough to reject the box squat. But is it possible that there is some component within the neuromuscular system that scientists have as of yet not discovered that would indeed warrant employing the box squat in your training? Could the original guess have accidentally hit on something? The way to get answers is to test the box squat hypothesis via controlled research. That’s what I’ll discuss in Part II.
Reference
Stone, M.H., M. Stone, and W. Sands. Principles and Practice of Resistance Training. Human Kinetics, 2007.
