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Are squats supposed to hurt your knees? I was in an exercise class yesterday and my left knee was hurting a bit while doing squats. Thankfully, I was able to correct the muscle activation sequence and my knee stopped hurting. But given the fact that squats are a mainstay of every cross fit or exercise class, learning how to squat properly is critical. As a physician who sees knee arthritis patients all day, the advice all over the internet seems to be missing the main point of how to perform a squat that won’t actually fry your knee cartilage.

Most of the squat-related information is centered on the structure of the squat. For example, making sure your knee is aligned with the hip, or making sure your knee is in front of your ankle. While controlling your knee position is important, all of that misses the main problem of poor muscle activation patterns.

The Perfect Squat is Driven by the Hamstrings and Butt

When most of my knee arthritis patients perform a squat, they universally recruit the thigh muscles. So does just about everyone squatting with weights, or as part of the latest cross fit exercise. That’s because we all conceptualize that the reason we’re doing squats is to build up the quadriceps. However, a squat isn’t supposed to work that way. The hamstring and butt muscles are actually supposed to be the main driver of the squat, not the quads, with the front thigh muscles only acting as a secondary helper.

Check out the video to the right. In the first few squats, the concentration is on the quads, while in the last few it’s on the butt and hamstring. When you focus on your quads, the knee cap is pulled into its groove and this puts too much pressure on the cartilage underneath. Any inability to control the knee’s lateral movement, or how muscles are activating, can cause the knee cap to get out of position in its groove, further increasing the pressure on the cartilage. The last few squats on the video shows the focus on the butt and hamstrings, which takes the pressure off the knee cap.

The Long Term Effects of the “Quad Dominant Squat”

It’s no coincidence that the most common knee problem in low back pain patients is arthritis under the knee cap, which fits in with this quad dominant squat. Most of those patients have low level nerve irritation (that they don’t notice) at the L5 and/or S1 nerves. This takes the butt and hamstring muscles off line and makes it harder to unconsciously activate them. All of that leads to a quad dominant squat, which in turn wears down the cartilage under the knees. So paying attention to how you’re doing squats becomes doubly important if you have any kind of back problem.

So how can you protect yourself? My left leg has some very low level issues from an irritated nerve in my back (but my back doesn’t hurt much), so my gluts and hamstring tend to shut off. I practice focusing on my butt and the back of my thigh every time I climb stairs. This becomes a conscious thing to kick those muscles back into action. I also do that in exercise classes or while engaging in cross fit. I literally focus my attention to the back of the leg and butt and away from the quadriceps. Give this a try first.

After you master this part, you can then worry about your hip, knee, and foot position. So the sequence would be:

1. Initially focus on the butt and hamstring and away from the quads
2. Knees shoulder width apart, but you may need to adjust this position as you squat to keep them more inside and prevent them from drifting out
3. Feet are turned out to a comfortable position
4. Push your butt back with a straight back (which sometimes doesn’t apply if you’re squatting as part of a specific exercise)
5. As you go down and up, continue to focus on recruiting the butt and hamstring, they should be driving the power of the squat

The upshot? There’s a ton of advice on how to squat from many sources, but not a lot of information from physicians who see the consequences of a lifetime of bad squats. Learn how to focus your attention on the back of the thigh and butt and away from the quads. Your thighs will still get toned and more powerful, but without the knee cap arthritis!