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Deep Squatting – Page 3

by Anders Hansson

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The reason for the difference in load

We are all aware of the fact that a deeper position requires more of your muscles. It is harder to get up from a low sofa than from a high chair. But why, exactly, is this so? Why do you perceive a deep squat as much heavier than a shallow squat? It is true that you work a longer distance, and thus perform more work per repetition, but that is a factor that makes itself felt only after several repetitions. The reason for the deep squat being tougher from the start, must be due to the muscles having to operate more closely to their potential maximum.

One reason for this is that the force, i.e. the weight of the bar, is acting on hip and knee joints through a longer lever arm. This increases torque, and since muscles apply their force on rotating joints, it is torque and not the weight alone, that decides the magnitude of the load.

To help you understand how torque is affected by depth, execution, and body proportions, we offer yet another interactive application.

But whereas the lever arms of the external force increase with increasing depth, the lever arms of the muscles at the same time decrease. And since it is the lever arms of the muscles along with their force which decide the opposing torque of the muscles, you have to compensate shorter lever with more force as you go deeper inch by inch. This relationship holds true for both the lever arms of the hamstrings and gluteus acting on the hip joint, and for the lever arms of the quadriceps acting on the knee joint. We are talking about dramatic differences here – in a deep position, the lever arm can be as little as one fourth of what it is in a shallow position.

To help you understand how the lever arms of the muscles depend on joint flexion, the interactive application below is very useful.

The relationship between the lever arms of the weight and the lever arms of the muscles is the main explanation for the fact that a much lower weight is enough – perhaps less than half of what would be required for a shallower squat – and still it stresses the muscles just as much.

Implications of the difference in load

A lower weight on the bar means less stress on the rest of the body, since you can maintain stress on the muscles of the hip and the knee by simultaneously increasing the depth. Put reversely: if you choose to do shallow squats, you may need to load the bar with perhaps 100 additional kilos to maintain the same muscular stress. That means 100 surplus kilos of completely unnecessary stress on the bones and, crucially, the joints.

This is not unique to the squat: In all strength training you'd do well to minimize the external load by maximizing the lever arm of the weight, while minimizing the lever arm of the muscle. This is the preferred modus operandi in almost all barbell exercises. Your chest muscles can handle much heavier weights in bench press if you lower the bar only halfway to the chest. They are, however, not better exercised (on the contrary, worse) and you expose your elbow and shoulder joints to unnecessary stress. Moreover, the risk of accident – with severe consequences – is obvious!

Like the weight’s lever arm acting on the hip joint, the weight’s lever arm acting on the lower back vertebra depends on the forward bending of the back. It increases down to parallel and then decreases slightly. Unlike the leg muscles, however, the lever arm length of these back muscles is constant throughout the movement as they only do static work. Accordingly, the stress on the back muscles depends only on the weight of the bar and the angle of the back. While it’s true that you attain the maximum angle of the back in a parallel squat, the load is so much lighter than in a half squat that the stress on the back muscles is less all the same. At a lower depth than parallel the stress is even smaller as you don’t lean forward as much and the weight inevitably is lighter.

As a matter of fact, a full-depth squat is normally the only squat variant where the legs are stressed more than the back. To stimulate the leg muscles satisfactorily with shallow squats calls for a greater load than the back can handle without support from a firmly tightened belt. Even with far from maximum loads, the weights during shallow squats are large enough to cause enormous torque on the lower back vertebrae when staggering or swaying sideways just a little. To avoid accidents a supporting belt is therefore mandatory but not always sufficient.

With deep squats, however, the load on your back tends to be just right so that you can make do without a belt and as an additional benefit get a very effective workout for the lumbar extensors without losing emphasis on the leg muscles. Anxious complaints of back pain are to be expected from deep squatting neophytes as they recall all the horror stories they have heard about the exercise. But they are in fact only suffering common “delayed onset muscle soreness” in the muscles of the lower back.

We noted earlier that it can be difficult to achieve consistent depth when you are not going rock bottom. Since the load on the muscles is rapidly changing for every extra inch in depth, we now realize why you run such a large risk of getting into a position too deep for you to handle when doing shallow squats. To make it even worse, you are also in a relatively high position, and can therefore easily lose balance. Furthermore, you have a lot of weight on the bar and the height of fall is large. To avoid serious accidents, you therefore need two or more “spotters” or access to a power cage with horizontal bar catchers on each side. Because of this it is common, especially among girls, to stick with weights far below maximum load to avoid the risk of failure.This makes the training more or less meaningless.

Note: Of course you can find yourself in a spot where the load gets the better of you even in a deep squat. But you are then in a low, stable position and can simply let the significantly lighter weight roll down and drop behind your back. There are always risks with squats no matter how you do them, and for that reason you should stop the set as soon as you feel your power waning as you otherwise might begin to compensate lack of leg strength with a strong forward lean of the torso and/or inward rotation of the knees.

Finally a purely practical implication deserves mention. Deep squats require less weight plates which make it possible for more people to train simultaneously and reduce time spent loading and unloading plates. Rather important factors when training a team of young hobby athletes who have to manage both sprint, jumps and barbell training in one session and then hurry home to homework and meals.

Athletic Design, 31 March 2009

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