Is it okay to do deep squats? I’ve heard it can be bad for your knees, but I’ve also heard it’s important for quad and glute development.
If it’s any consolation, you’re not alone in your confusion. In fact, there’s a lot of debate in the fitness industry about how far down you should go in a squat. Some practitioners warn against parallel squats, citing an increased risk of muscle and connective tissue injury. However, based on research, these concerns are largely unfounded for much of the population.
While it’s true that shear and compression forces tend to increase with increasing knee angle, the actual forces absorbed by the anterior and posterior cruciate ligaments are quite small in the full squat. This is due to the fact that the knee is severely restricted at angles greater than 120 degrees, resulting in much less displacement and rotation of the tibia (i.e., tibia) compared to smaller flexion angles. The limitation is attributed to the collision between the upper tibia and the femur (thigh bone) and the compression of various soft tissue structures such as the menisci, hamstrings, fat and skin. The result is better knee stability and greater load tolerance.
It can be argued that the riskiest part of the squat is actually in the earlier stages of the movement. Anterior cruciate ligament (ACL) stress is highest at about 30 degrees of knee flexion, while peak forces on the posterior cruciate ligament (PCL) occur at about 90 degrees of flexion — the point where you reach parallel. But that’s not as threatening as it might sound.
The highest forces recorded in a research study were in powerlifters squatting two and a half times their body weight (over 500 pounds!), and those forces were still well below the strength capacity of the cruciate ligaments and patellar tendon. It’s also important to remember that when you lift weights on a regular basis, connective tissue gets stronger. This means your ligaments and tendons adapt to the regimented squat by increasing their tolerance levels, further reducing the likelihood of injury.
That’s not to say that deep squats are safe for everyone. Those with existing knee problems or who have had knee surgery are generally best served by limiting the depth of the squat to around 50 degrees of flexion (a partial squat). The menisci are particularly sensitive to pressure and absorb the greatest stress at high flexion angles. So be extra careful if you have sustained an injury to this structure. But as long as you have healthy knees, you shouldn’t have any trouble parallel squatting.
In light of these revelations, the question is: is it beneficial to deep squat? The answer to that really depends on your goals. The quadriceps are maximally active at about 80 to 90 degrees of knee flexion. So if your goal is to maximize hamstring development, parallel squats are probably your best bet. On the other hand, the glutes become more and more active in the squat as you descend past 90 degrees and peak near the bottom of the movement. So if your goal is a better butt, a deeper squat is generally preferable.