This past weekend I did a "mothers boot camp" with my wife. It was a great class. The instructor did a great job of pushing them. My wife had a love, hate relationship for her. She loved the workout, but hated that she pushed them so hard. I participated and found the workout to be a great workout…it was intense enough for all fitness levels….it would have also kicked a lot of men’s rear ends.
The only point I have is that this was a perfect time for me to continue on this series of the biggest or worst workout mistakes.
The trainer had everyone lie on their backs and have their partner stand above them. As the person lying down raised her legs up to the sky, the partner would throw her legs back down. This is supposed to strengthen the abdominals…but in reality the only thing it does is strengthen the wallets of chiropractors and physical therapists.
It is probably the biggest misconception that "lying or hanging leg raises" works the abdominal muscles. The same is true for any exercise that has you raise or hold your feet 6-12 inches off the ground. Because if you look at any anatomy and physiology book or open up a cadaver…you will see that the muscle(s) involved in raising the legs are the hip flexors or appropriately called the psoas muscles. Those are the muscles that raise the legs. The abdominal muscles perform an isometric contraction, which are good but isometric contractions are not nearly as beneficial as concentric and eccentric contractions that occur when you actually move the muscles.
Let’s explain how muscle contractions occur. A muscle is like a rubber band. It attaches at two different points, usually on two different bones. What makes the muscle contract is when the two endpoints come closer together. Take for example the bicep curl. The bicep muscle attaches below the elbow and at the top of the shoulder. When you bend your arm or elbow to do a bicep curl…the two endpoints come closer together. When you extend or stretch your arm….the two endpoints go further away from each other. This lengthens or stretches the muscle.
For contraction to occur the two endpoints need to move closer together. This happens in all muscle contraction, from push-ups, calf raises, squats and of course abdominal crunches and leg raises. The abdominal muscles attach on the lower portion of your ribs and runs down to attach on the top portion of your pubic bone. When these two points come closer together you get contraction of the abdominals. If the points don’t move closer…there is NO muscle contraction.
When you do a correct crunch you are supposed to only pull your upper body a few inches off the floor. You are literally crunching your tummy. You don’t need to do a full sit-up. That slight movement causes the abdominal muscles to contract. Try it…place your fingers at the bottom of your rib cage and at the top of your pubic bone and do a crunch…you can do it while you are sitting reading this. Are you fingers moving closer together? They probably are, which is how you contract your abdominal muscles.
So best advice don’t do any movement like lying leg raises, or holding your feet off the ground, because it is only going to hurt your back. And Don’t think that putting your hands behind your back is going to help. It will lessen the pain, but you are still overworking your hip flexors, which for most people who sit at a desk, work on a computer, sleep in the fetal position, drive or fly… a lot will already have overly tight hip flexors and tighten them further with leg raises is great for my pocket book.
As I said, you could do them, but don’t be surprised if one day you say to your chiropractor or physical therapist…I was just bending over to pick up my workout shoes and my back went out. I have heard that so many times and I can track it back to leg raises, and long hours sitting.
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