The biomechanics of squat variations matter if you have recently injured your knee and you are in the process of rehabilitating functional movement patterns.
This post is not applicable to acute knee injuries.
Torque and Moment Arms
In order to understand the biomechanics of squat variations, you must first understand the two important concepts of torque and moment arms.
Torque is the rotational force that is required to move a joint. For example, in order to perform a bicep curl with a dumbbell, the biceps must generate enough torque to rotate at the elbow joint (axis) to bring the weight upwards.
A moment arm is the distance between the axis and the force applied. To build on the previous example, the moment arm would be the distance parallel to the floor between the elbow and the dumbbell.
As the moment arm increases, the torque (force) required to move an object increases as well. Below is a diagram to illustrate this relationship between torque and moment arm.
If this all seems too confusing – ask yourself is it easier to hold a weight closer to my body or hold the weight further away from my body? If you can conceptualize that holding a weight further away from your body is more difficult, then we can move forward onto squat variations and the moment arms associated.
Squat Variations and Moment Arms
As you can see, the low bar back squat has a significantly smaller moment arm at the knee joint, especially when compared to the front squat. In other words, the low bar squat places less stress at the knee joint and surrounding musculature. Therefore, the low bar back squat may be a viable option when reintroducing the squat movement pattern into a late stage knee rehabilitation program.1
What if the low bar back squat still provokes my knee pain?
If this is the case, when performing a low bar back squat, you can place a high box behind you to touch lightly down on.
By adding a high box, you are decreasing the range of motion of the movement and ensuring that you will not go past a depth that aggravates your knees. After training at a certain height without knee pain for an extended period of time you can decrease the height of the box to further challenge the movement.
Below is video on how to perform the box squat.
Conclusion
I purposely kept this blog short and sweet. There are many causes of knee pain when squatting and this is by no means a complete guide on this topic.
If you are in the Vancouver area, do not hesitate to contact me to schedule a chiropractic appointment to discuss a functional knee rehabilitation strategy that works for you.
References
- Horschig, A. (2016). The Real Science of the squat. In The Squat Bible (pp. 118–124).
Dr. Brandon Parnham, DC 