“No. This is incorrect. The bottom is larger but because of the shape of its articulating facets and the resulting increased mobility….It isn’t the strongest/most stable. Just the opposite. The lumbar spine is highly unstable when compared to the thoracic spine.”

No shit. You already explained that, but since you said “I don`t follow your logic,” I basically had to walk you through our conversation again. I didn`t write that so you could correct me again.

“When doing a horizontal leg press, the force from the leg press travels axially through the lumbar spine. A hip belt squat also applies an axial force on the lumbar spine although it is more of a traction force. The Barbell back squat applies shear forces at an angle increasing the risk for disc herniation ONLY if performed incorrectly with enough weight. It’s not necessarily or inherently bad. By the way, the force doesn’t just stop at the lumbar spine, it continues it’s way down the pelvis, and lower extremities. My point is that there is ALWAYS a force being stressed through lumbar spine no matter which variation you use.”

Let me quote myself: “There’s more weight pressing down during a barbell squat then there would be pushing up or sideways during other exercises.”

Gravity means more force from certain exercises then others. Barbell squats don`t create the same stress as a hip belt squat on the spine.

“It does matter. The thoracic spine along with the muscles of the upper back (principally the trapezius) create a stable scaffold for the barbell which will allow you to perform the movement safely. A thoracic spine that is unstable or lacking in thoracic extension will cause problems further down the chain in the lumbar spine, which could predispose you to injury.”

No it doesn`t matter when it comes to the point I was making. Taking it out of context, then of course it matters.

“No you can’t. And You CAN NOT bend 90 degrees at your low back either.

The 90 degree bend that you are talking about actually occurs at the iliofemoral joint (ie at the hip)”

I´m glad you did know what I was talking about. I was calling the hip, the waist, by mistake. Because we have to be able to bend at the hip, the lumbar doesn´t have the surrounding structure of your middle back. If we had to bend at the middle back like we do at the hip, then you´d probably hear about mid-back pain more often was my point.

No. This is incorrect. The bottom is larger but because of the shape of its articulating facets and the resulting increased mobility….It isn’t the strongest/most stable. Just the opposite. The lumbar spine is highly unstable when compared to the thoracic spine.

“The top is also more mobile, so more prone to injury. Then you said it’s not loaded at the top, but middle, which is stable, while lumbar isn’t. Then I said, the weight from a barbell endangers the lumbar because the pressure travels downward so your lumbar spine is dealing with that weight, and since you yourself said it’s unstable, that’s not good.”

When doing a horizontal leg press, the force from the leg press travels axially through the lumbar spine. A hip belt squat also applies an axial force on the lumbar spine although it is more of a traction force. The Barbell back squat applies shear forces at an angle increasing the risk for disc herniation ONLY if performed incorrectly with enough weight. It’s not necessarily or inherently bad. By the way, the force doesn’t just stop at the lumbar spine, it continues it’s way down the pelvis, and lower extremities. My point is that there is ALWAYS a force being stressed through lumbar spine no matter which variation you use.

“Regardless, pyramid or no pyramid, your spine is in trouble from a barbell on your back. It doesn’t matter how stable your thoracic spine is.”

It does matter. The thoracic spine along with the muscles of the upper back (principally the trapezius) create a stable scaffold for the barbell which will allow you to perform the movement safely. A thoracic spine that is unstable or lacking in thoracic extension will cause problems further down the chain in the lumbar spine, which could predispose you to injury.

“A multi-hundred pound barbell pressing down on my spine sounds dangerous, especially if I have to bend downward to squat with it.”

Only dangerous if you can not maintain proper form. Lower the weight, simple as that.

“My spine would be much better off, not going through that, since the purpose is to workout my legs.”

If you prefer leg press, have at it hoss. Exercise choice is your call/personal preference. I don’t have an issue with that. I only take issue with the perpetuation of false information regarding the human spine and biomechanics which this post is chock-full of.

“So you can bend forward at a 90 degree angle from your middle back? If no, then you know what I was getting at.”

No you can’t. And You CAN NOT bend 90 degrees at your low back either.

Normal flexion active range of motion values for the spine are as follows:

Thoracic: 20-45
Lumbar: 40-60

These ranges account for individual differences as well as different ranges between veretbrae.

The 90 degree bend that you are talking about actually occurs at the iliofemoral joint (ie at the hip)

There’s more weight pressing down during a barbell squat then there would be pushing up or sideways during other exercises. It’s called gravity.

The rest of what you said is nonsense.