Starting Strength

thighs crowd your hip pointers, they tend to trap any soft tissue or muscles that may be in the area in between, making it harder to go deep. (See Figure 2-43 .)

    Figure 2-43. Hip impingement (A, left two panels), the primary factor limiting squat depth. Note that impingement does not occur in B (right panels). This contradicts the conventional wisdom of the hamstring-flexibility theory of squat depth, and it pleases us to do so.

    Squat depth is a function of hip angle, the angle formed between the generalized plane of the torso and the femur. If you try to drop down to get better depth without adjusting the position of your femurs, you’ll get depth at the expense of a rounded lower back because the hip angle cannot become more closed if the femurs are impinged. The pelvis is supposed to be locked in line with the lumbar vertebrae and held rigid by the erector spinae muscles. If the pelvis can’t tilt forward to maintain this position because it rams into an obstruction, the only way to keep going deeper is to round the low back. Everybody, big belly or not, will experience this phenomenon to one degree or another, so if you’re having depth problems, shoving the knees out fixes these problems so often that it is a waste of time to do anything else first.
    Most people won’t do the job of keeping their knees out unless they’re coached; the knees want to track more medially because of the tension felt on the inside of the femurs. This tension is produced by the adductors – the groin muscles. These five muscles (the adductor magnus, adductor brevis, adductor longus, pectineus, and gracilis) attach at various points along the medial and posterior aspects of the femur, and on the ischium and pubis of the pelvis. Tension is produced between these two bones as you squat down and keep your knees out; this is an eccentric action for these muscles because they lengthen on the way down – if the femurs maintain their position parallel to the feet. As you come up out of the squat and the hip angle opens up, the distance between the inside of the femur and the medial pelvis shortens, so the concentric action of the adductor muscles thus produces hip extension. (See Figure 2-44 ).
    Visualize the function of the adductors by imagining a point at the end of the inside of your thigh down by your knee, and another point on your “seat bone,” under your butt and behind your crotch. These points represent the attachments of the adductor magnus. Your spinal erector muscles lock your back in extension and lock your pelvis in line with your back, so as you squat down and make your back more horizontal, your seat bones rotate back and away from your knees. If your knees stay in position, pointed in the same direction as your feet – out at about 30 degrees – the distance between the point on the inside of your thigh and your seat bone increases. And if this distance increases as you go down and decreases as you come up, the muscles that get longer on the way down make the “up” part happen as they get shorter. This is how the adductor muscles function in a correctly performed squat and why they are considered hip extensors, along with the glutes and hamstrings, as part of the posterior chain.
    Since the adductors tend to pull the knees in, what keeps them out when you use your hips correctly? If ad -duction of the thighs means pulling the distal end of the femurs (the knees) toward the midline of the body, it seems like ab -duction would be the movement used to keep the knees out, and that the abductors would be the muscles that did this. But the abductors consist of only the tensor fascia latae (TFL, a small muscle that connects the hip at the anterior iliac crest to the lower leg), the gluteus medius, and the gluteus minimus. Together they create hip abduction if you raise your leg out to the side, away from your body. Since nobody actually does this, except to demonstrate the definition of abduction in biomechanics class, this is probably not what is going on when we squat.
    External rotation occurs when you make your right femur rotate clockwise and your left femur rotate counterclockwise, as when you stand up and pivot on your heels to rotate your toes away from each other. There are at least nine muscles that perform this function: the gluteus medius, minimus, and maximus, the adductor minimus, the quadratus femoris, the inferior gemellus, the obturator internus, the superior gemellus, and the piriformis. (Notice