“Hey there buddy, what are you doing?” I asked as I walked by a dude doing some pretty crazy looking leg raises.
“Just some abs,” he replies, “I’m really trying to get my core in shape for the summer”.
Not surprised by his response I ask, “Why do you have your hands under your hips?”
“Oh, well, whenever I do these it really makes by back hurt so I put my hands there to make the pain go away.”
“How does that make your back stop hurting?” I ask.
“I don’t know man, it just does!” he barks back.
I know tons of people out there that do this exact same thing. Often people will do an exercise, then modify it to accommodate their strength levels. In the case of the leg raises, people will place their hands under their hips because it makes their back stop hurting. Most of the time, when I ask people why they immediately place their hands in that position, they respond by saying that ‘someone told them to because it keeps their back from hurting’. They don’t know why it helps, they just know that it does. In this post I am going to address the leg raise and explain why it is a great exercise, but that placing your hands under your hips will likely cause some long term low back pain.
Before I get into this, be prepared for a litte nerd trainer talk. I warned you! So let’s get into it. Here are some questions and answers to guide us along. I’m a huge fan of The Office, so we will have some Dwight False action going on.
What kind of exercise is the leg raise?
The leg raise is a super exercise for the lower abs.
False. The leg raise is an okay exercise for lower abs, but a better exercise for the hip flexor muscles.
In reality, the abs are simply stabilizing the trunk while the legs are moving up and down. Because the abdominals do not attach to the femur (the upper leg bone) they aren’t doing any movement at all. In fact, the abdominals are preventing movement! The hip flexor muscles such as the rectus femoris (one of the four quadriceps muscles) and the psoas are the main muscles being used during the leg raise.
So you may be wondering how the hands under the hips keeps the lower back from hurting? Here is why: Placing the hands under the butt rotate the pelvis backwards and prevent the pelvis from rotating forward. Make sense? Try this out:
Lay on your back and place your hands off to the side with your legs straight up into the air. Notice that the small of your back is flattened against the floor (this is what I mean when I say the pelvis is rotated backward). Now, lower your legs slowly and notice how the small of your back wants to move away from the floor (this is what I mean when I say the pelvis is rotated forward). The muscles that prevent this pelvic rotation are the abdominals.
Now, raise your legs in the air and place your hands under your butt. Then, lower your legs towards the floor. Notice how much easier it is to keep your lower back from rotating away from the floor?! The reason it’s easier is because now your hands are doing the job of the abdominals. If you continue to do this, your hip flexors (the muscles that are actually moving the legs) will continue to get stronger while the abdominals get relatively weaker.
Placing your hands under your butt is an external crutch that will lead to internal problems. In this case, strengthening the hip flexors without strengthening the abdominals will likely lead to lower back pain in the future.
If you want to do leg raises, but it hurts your back try it this way:
1) Lay on your back with your hands out to the side.
2) Raise your legs straight up in the air.
3) Lower your legs slowly until you feel your lower back move away from the floor.
4) Once you feel your lower back move away from the floor, lift your legs back to the start position.
Doing the leg raise this way will train the abdominals to stabilize the trunk as the legs are moving up and down. If done correctly, it can be a great exercise. If it is done incorrectly, it may cause some problems in the future.
Look for Part 2 of Internal Crutches Lead to External Problems coming soon!
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