In my five years as a CrossFit trainer, I have never taught a back squat without first having to remind someone of the “low-bar” position. The default position on the back, especially for beginners, always seems to be high on the traps, and rightfully so. At the top of a back squat it is much more comfortable for the bar to sit as high as possible. And who doesn’t want to be comfortable? But that doesn’t mean that’s how we want you to back squat. ”High bar” and “low bar” positions offer very different experiences and work very different muscle groups. If you’ve been a regular at CFK for a while now, you’ll know we prefer the low-bar back squat. Here’s why.
Back squats work your legs. Bar positioning changes the part of the legs being worked.
A low-bar back squat is a barbell movement unique in its ability to work the whole of the posterior chain (hamstrings, glutes). The posterior chain consists of the muscles that produce hip extension (the straightening out of the hip joint from its flexed/bent position in the bottom of the squat). During any back squat, the bar must stay over the mid-foot. Any deviation in either direction will cause the lifter to fail, given a heavy enough load. A low-bar position will require the lifter to angle the torso forward more than any other squat in order to keep the load over the mid-foot. A flatter back means a a smaller hip angle. Squatting in this manner will keep your hamstrings tight during your decent and will require their use in ultimately re-opening the small hip angle on the way back up.
A high-bar back squat is more similar to a front squat than a low-bar back squat. In order to keep the bar over the mid-foot, very little (or no) torso lean is required. From the picture above, also notice the greater hip angle at the bottom of both the high-bar back squat and the front squat. Back angle largely determines the hip angle. Because the hips remain open, very little additional hamstring contraction is required/used to open the hips while standing. Instead, the focus is on extending the small knee angle that is produced. The primary knee extensors are the quadriceps muscles, thus the fatigue in your quads you experience when front squatting.
Which Should You Do?
There is a time and a place for each of these. At CFK we get plenty of quadriceps work in when we overhead squat, front squat, snatch and clean. Most of us need extensive posterior chain work. When a back squat appears in a WOD, or you decide to use it as part of your extra lifting, be sure to use the low-bar variation. It is much better at producing overall strength, as well as explosiveness.