Squat Report: Lower Back
Now this is where things really start to get interesting. The lower back.
It is one of the most (in my opinion) flimsiest parts of the body, next to the shoulder. Which is why it is one of the most susceptible areas to get hurt.
I am not going to get into much detail on anatomy as I will exhaust this subject a couple months down the road so please keep an eye out for that. What I will do this month is sum up the anatomy and muscle part, so I can explain, or at least try to explain what is going on during the plantar flexion and dorsiflexion phases of the squat.
The lower back consists of 5 lumbar vertebrae (L1-L5) and the sacrum (S1-S5) I went into great detail about the sacrum a couple of weeks ago, so I won’t touch that one just refers back to it when you get a chance. There are also about 8 muscles that help the low back stay strong and keep you upright. We will get into those in a bit, but for now we are going to briefly explain the structure of the bones of the lumbar vertebrae.
The lumbar vertebrae are the largest and most condensed bones we have in our spinal column. And they need to be! They take huge amount of force from the upper body and must transfer that to your hips all the while keeping the ever-precious nervous system protected. The picture below shows the difference between the three areas of the spine.
For now, I think it might be a good idea to leave the anatomy lesson until we really get into the anatomy part of the lower back so, let’s move on to the muscles and briefly go over them.
The muscle constitutes of about two layers (inner and outer) and 8 exclusive and a ton of supporting “staff”. We will focus on the 8 exclusive muscles and then mention the supporting guys.
The 8-exclusive staff of the lower back are:
- Psoas Major
- Intertransversarii Lateralis
- Quadratus Lumborum
- Intertransversarii Medialis
- Longissimus Lumborum
- Iliocostalis Lumborum
The supporting staff can consist of but is not limited to:
- Rectus Abdominus
- External Obliques
- Internal Obliques
- Latissimus Dorsi
- Serratus Posterior Inferior
Again, I am not going to go into this in detail just give you guys a quick overview of how the low back is made up. Now onto how the low back plays an integral role while you squat.
Your lower back actually flexes, this causes the front part of your spine to “open up” and the back part of your spine to “close” when this happens the muscles on the back side, the 8-exclusive guys, have to fire to keep tension on the spine so that you can control the mass that is on your shoulders (assuming that you are performing a squat with the bar on your shoulders) from crushing your lower back into five separate bits.
Conversely, the supporting cast must fire as well. The rectus abdominus, external/internal oblique must fire because the moment arm that has been created (red arrow) and with the combination of the lower part of the trapezius, lower part of the latissimus dorsi, serratus posterior inferior creates an inter abdominal pressure.
During Plantar Flexion
Ironically, the same pretty much applies during the plantar flexion phase of squat. The difference is very miniscule with the supporting staff as they slowly (or supposed to be slowly) ease off. The main workers still must be “on” because of the downward force of the bar but as the spine “straightens” the forces slowly allow the muscles to elongate once again. The biggest difference here happens that instead of using your muscles as a “breaking effect” against gravity, they are engaging their efforts to get you back into a standing position which is where we like to be.
One of the biggest mistakes I consistently see on the gym floor is that people completely relax their legs and “shake off” the pain from their legs with the load still on their shoulders. Doing something like this can cause your lower back to explode (I’m not exaggerating, it can actually explode) so please do this “shaking off” when you rack the weight.