Have you wondered…..
Q & A: Are crunches bad for your back?
A: In a word – no. They’re quite safe. In more words, I’m eating my words from 10+ years ago when I used to warn people about the “dangers” of crunches (or any exercise where your spine moves).
What about the pig spines?
Dr. Stuart McGill is the primary person who convinced me that crunches (and anything else where the spine moves) are dangerous. He did this with pig spine research. He got pig spines from a meat packing plant, and put them into little “crunch simulation machines” – machines that bend the spines in a crunch-like-manner over and over again. After 80,000+ reps in the machine one of the pig discs would pop. He’s got a PhD, and a killer mustache, so it never occurred to me to give it more thought.
After McGill later said, “Crunches are neither bad nor good” it was like hearing the tooth fairy didn’t exist. Here are the big problems with the pig spine research:
1. Passive and paralyzed: The experiment above tells us what we already know – paralyzing someone and then bending their spines 80,000x is risky. Common sense says “duh.” Common sense also says that “in exercise the living human moves her own body with her own muscles – meaning she can adjust and stop the movement based on how things feel.”
2. Neck vs low back: upon closer reading of McGill’s original paper the rupture was in the neck not the lower back. Our lower spine is 4x the size of our cervical spine (or neck). Given that McGill had the whole spine and was publishing on the lower back, I suspect he avoided using the lower back portion because it was too strong and tough to get it to fail. (For reference, a woman’s spine can handle 1,300 pounds of downward force without failing.)
3. Recovery: This is 2-fold:
o who does 80,000 reps in a single workout? With fast (1sec) reps it would take 22 hours to complete all of these reps.
o Tissues recover between workouts, if you’re alive and all.
Bending = Good
It turns out that moving your spine is both unavoidable and good for you. Our spines have 25 joints in them that go side to side, front to back and even rotate – if the spine was supposed to be motionless then it would just be one big bone similar to the one in your thigh (your femur).
The discs between our spinal bones (vertebrae) need movement to be healthy, heal, do self-maintenance, etc. Our spinal discs are big pieces of cartilage that do not have their own blood supply. Tissues without dedicated blood supply depend on the pumping action of motion instead of the pumping of your heart, and without enough motion they degenerate.
Bottom Line on Crunches
Fearmongering is good for clicks, but bad for people. While we do get plenty of aches and pains, that’s not the same as being fragile. Fragile means something that breaks or fails when stressed. Our bodies are the opposite of fragile – we get stronger, better and more resilient with stress. Furthermore we are harmed by avoiding stress (as in avoiding cognitive challenge or avoiding hard physical activity).
PS – What else have I been wrong about? Carbs…
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