Way back in the day when I was in PT school, Dr. Stu McGill was a name I kept hearing outside of the curriculum.
Turns out he was the leading spinal expert in the field and was well respected around the world for his knowledge and interpretation for spinal injuries.
One of his topics of interest was the occurrence of disc herniations, and he attributed sit-ups and crunches as one of the main mechanism for such injuries.
He stated “crunches and traditional sit-ups place 3,300 newtons (the equivalent of 340 kg!) of compressive force on the spine when bent in flexion. These forces can squeeze a bent disc’s nucleus to the point that it bulges – pressing on nerves and causing back pain, and potentially leading to a herniated disc.” - “He's Got Our Backs.” Health, 23 Nov. 2011, uwaterloo.ca/health/hes-got-our-backs. Click Here for the full article
Now I have listened to many podcasts and read more of his work as well, and what he does not want people to think is that flexing the spine is bad.
It is the repetitive flexion under increasing loads that cause the breakdown of our discs and ligamentous layers in the spine, which is exactly how most people perform sit-ups and crunches,
You've seen the people that hug a ton of weight and rapidly move back and forth.
Now you may be thinking, “man what am I supposed to do now”
Luckily, there are many, many, many, options for abdominal strengthening aside from situps and crunches.
What you want to be able to achieve is a controlled spinal position by engaging the obliques to help with rotation or maintaining stability.
One of our favorites is below.
This is challenging and provides stability to learn how to rotate and maintain a balanced position the whole time.
To make sure we are clear, I don't think flexing the spine is a bad thing.
This is a normal movement that occurs in sport and under some pretty high loads.
It's when someone increasing the volume and weight of these movements by going from 10 sit ups to 200 situps a day with 50lbs in a matter of 2 weeks is when you are going to be poised for injury.
Plus, when lilting heavier weights, we still need to learn how to control spinal movement to prevent excessive excursions so we can maintain better techniques in deadlifts and squats. A sit up does not really help in this situation.
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Dr. Peter Dionisopoulos is the owner and founder of Dynamic Performance & Rehab. He has a Doctorate in Physical Therapy and enjoys to help active adults maintain their lifestyle and provide natural solutions to their pain.