How many repetitions does your back have left?
I was recently listening to a webinar by Stuart McGill PhD, a researcher in Canada who has made it his life’s mission to solve the puzzle of low back pain. He was speaking about recent research that has shown that flexion-type exercises such as sit-ups, crunches or ab machines increase lumbar disc degeneration by overloading the delicate structures of the low back.
For the past year, we have eliminated the use of all flexion exercises in our rehab department and also have been encouraging patients not to do sit-ups and ab machines at the gym — especially if they already have low back pain. Sometimes it’s hard to convince patients that there is inherent risk with these exercises. After all, we all have been doing sit-ups since we were in PE class.
Dr. McGill used an example that I think will help patients better understand why flexion exercises increase risk for low back pain. If you wanted to make a break in a wire hanger, what would you do if you didn’t have wire cutters? You would repetitively bend the hanger at the spot that you wanted it to break. After a few dozen bends, you would have two pieces of wire hanger. Mission accomplished.
The lumbar spine (low back) has the same properties as that wire hanger. Every low back has a limited number of “bends” until something breaks. The number of “bends” each back has in its capacity is predetermined by genetics and other injuries that we may have experienced over the years. Since we all need to flex forward to accomplish certain movements and tasks, the best strategy to avoiding low back pain is to limit flexing to when we need to do it — not burning up thousands of repetitions through sit-ups.
So instead of using up your reserve through sit-ups (which are very ineffective ab exercises, by the way), investigate the use of bridging, planks, bird-dogs and other dynamic floor exercises which have been shown to prevent low back pain by stabilizing the spine — avoiding flexion. And as always, if you have questions on how to add this into your home exercise program, please let us know and we’ll be sure to set aside time to assist you!