20 Things from Dr. McGill (2 of 4)

About the Author: Eric Cressey

I’ve seen Dr. McGill in seminar before, and by my own admission, I’ve always been more of a “listen and watch” guy than a note-taker. However, that’s not to say that I didn’t hear a lot of great points that went right to my notepad. Here were some highlights along with (in some cases) my commentaries on their applicability to what we do:

6. Shear forces are far more of a concern than compressive forces; our spines actually handle compressive forces really well. You can’t buttress shear effectively in flexion, so it’s important to avoid it – especially at the most commonly injured lumbar spine segments – at all costs. The spine doesn’t buckle until 12,000-15,000N of pressure are applied in compression, but as little as 1,800-2,8000N in shear will get the job done.

7. The rectus abdominus is not about trunk flexion; it’s an anti-rotator that is responsible for transferring hoop stresses. If it was about trunk flexion, it wouldn’t have the lateral tendinous inscriptions; we’d have hamstrings there instead!

8. Don’t just train the glutes in hip extension; really pay attention to their role as external rotators. Once you’ve mastered linear movements (e.g. supine bridges), you need to get into single-leg and emphasis movements like bowler squats and lunges with reaches to various positions. These are great inclusions in the warm-up.

9. Contrary to popular belief, the vertebral bodies – and not the discs – are the shock absorbers of the spine. Amazingly, the elasticity we see is actually in the bone; blood is responsible for pressurizing the bone.

10. End-plate fractures are the most common injury with compression; they almost always are accompanied by a “pop” sound.

Eric Cressey

P.S. As an interesting aside to all of this, Dr. McGill and I actually spoke at length about the importance of hip mobility – something that obviously is closely related to all twenty of these points. If you lack mobility at the hips, you’re forced to go to the lumbar spine to get it, and that is a serious limitation to building stability. On several occasions, Dr. McGill alluded to Mike Robertson and my Magnificent Mobility DVD, so if you’re looking to protect your back, improve performance, and feel better than you ever thought possible, check it out..