Squat Report: Hip Part I (Flexion)
Over the past few months we have put our focus directly on the lower body, and rightly so, it is an integral part of, not only the squat but for, everything that we do.
The next couple of weeks we are going to turn our attention to the transitional forces that happen between upper body and lower body. And I cannot find a better place to start than our hips.
The hips are one of those areas that connects upper body to lower body, its no wonder why it houses the most powerful muscles that we have. This week we will look into how and what happens to our hips during flexion, and why it happens.
Next month I am going to get into the detailed anatomy of the hip so for now here is a simple description and picture of this structure.
As you can see it constitutes of two simple structures, the pelvis, and the femur. Now when we are discussing flexion of this joint (specifically the head of the femur inside the socket of the pelvis) a few interesting things happen.
For one, when the head of the femur rotates backward in the socket of the pelvis flexion at the joint happens (femur comes closer to the pelvis) and a slight depression and external rotation happens at the femur (as you can see in the picture below)
The pelvis anteriorly tilts (the top part of the hip comes forward) causing the sacrum (bottom of the spine) to “tuck” underneath as if you are tucking your tail between your legs as the sacrum is not attached to the pelvis other than muscular attachments. This movement is extremely important as the bones need to move so that it can gain clearance from some of the physical obstacles in that are in the way the “deeper” you go into the squat.
As for the muscles that initiate and control this movement. Everything and anything that is in and around the hip must fire. A group, or a single muscle that does not fire will cause deviation in the tracking of the knee (Key indicator for a trainer that something is not working), or may cause a shift in the hips to the stronger side (indicator that something in the trunk is not working).
Back to the muscles. All of the flexors of the hip mostly have multiple jobs to do. For example:
- Psoas Major, controls spinal flexion, and some internal rotation
- Rectus Femoris, controls knee extension and contradicts the hamstring group
- Illiacus, controls the hip when flexing in a sit-up
- Sartorius, is also a weak knee flexor, and medially rotates the leg
- Tensor Fascia Latae, also helps in lateral rotation of the tibia
- Pectineus, also adducts (brings the leg inward toward the other leg)
- Adductor Longus, also adducts and medially rotates the leg
- Adductor Brevis, can also adduct, laterally and medially rotate the leg depending on the position of the leg
- Gracilis, also assists in medial rotation, adduction, and aids in knee flexion
Alternatively, the extensor muscles of the hip and trunk muscles also have to engage as if they don't, there will be some really massive dislocations in the hip and spine segments. We will discuss them in a few weeks’ time. But for now, just take into heart that the key movers are the ones listed here.
So, whenever we get into hip flexion we have all the medial muscle groups firing to help counter that external, lateral rotation and considering the amount force that is going through that little joint (head of the femur in the socket of the pelvis) these are some extremely powerful muscles.
As for anterior pelvic rotation, all the muscles noted above also engage to keep the pelvis in place. Some other muscles to take into consideration are the rectus abdominus and the erector spinae group but we will get into those when we discuss the pelvic griddle and in more detail in the spine section. For now, just know they do play a part in hip flexion and pelvic rotation.