Great looking abs are desired by both men and women, but lying or hanging leg raises are probably the worst exercise you can instruct someone to do. Unless you are a chiropractor, or physical therapist and hope to make money from their rehabilitation.

 

 

To understand why this movement is bad, you need to understand the basic bio-mechanics of how muscles contract to move the body. Anatomy and Physiology taught us that a muscle attaches at two ends. When those two endpoints come closer together we get muscle contraction. It is the contraction of the muscle that pulls the endpoints closer. When the two end points move further apart, the muscle relaxes and stretches.

 

For example, look at the bicep muscle. It attaches at the top of your shoulder and just below the crease of your elbow. When you bend your arm, or do a bicep curl, the two endpoints move closer together. When you straighten your arm the two points move further apart. 

 

Every muscle in the body works by this same “pulley” principle, including our eye muscles.  Look at the chest muscles. The pec’s attach along the side of your sternum and run diagonally into the top of your shoulder. As you lower the bar when doing bench press, the two end points move further apart. The pec muscles are stretching. As you push the bar off your chest, the two endpoints move closer together. This causes the pec muscles to contract.

 

 

The muscles responsible for raising the legs are the psoas muscles, NOT the abdominal muscle. The common name for the psoas muscle is the ‘hip flexor.’   The hip flexor attaches at the upper portion of your thigh muscle and sits beneath your abs and intestines and runs up and attaches to your spinal column, more specifically your lumbar vertebra and disc. These muscles are notoriously known for being the primary cause of back pain.

 

The abdominal muscles sit on top of your intestines and attach at the bottom of your ribs and run down past your belly button and attach to the pubic bone. Remember a muscle contracts when the two endpoints come closer together. 

 

To prove to you that lying/hanging leg raises don’t specifically work the abdominal muscles, let me get you to lie flat on your back as if you were preparing to do a leg raise. Place your right hand at the top of your pubic bone and your left hand on the bottom of your rib cage. Now slowly raise your legs up to the ceiling, to 90 degrees. Did your hands come closer together? I don’t think so!

 

If you keep your legs in that vertical position (90 degrees) and now pull them closer to your head, you will notice that your pelvis will begin to rock up towards your head. You should begin to feel your hands come closer together. Now you are doing a “reverse crunch” and your abdominal muscles are actually being exercised.

 

Lower your legs…keep your hands on the same positions…legs bent….feet flat on the floor….and do a regular crunch. Your hands should come closer together, which tells us that your abdominal are going through their full range of motion and are contracting and stretching the same way we contract all the other muscles on our body.

 

Hopefully, this will explain why crunches and reverse crunches are the best exercises to do for your abs. All you have to do is raise your shoulders a few inches off the ground or raise your pelvis towards your shoulders and you’ll get a great isolation movement that targets the abs. Doing leg raises, or holding your feet six inches off the ground or having someone throw your legs back down after your raise them is only going to make your hip flexors tighter and put you at risk for  back pain.

 

I see it so often; patients come to my office complaining of back pain. I ask them if they sit all day. Sleep in the fetal position? Take long trips? Or, what kind of ab workout do they do? If they say, lying or hanging leg raises or some other type of similar movement…..I gently apply slow, deep pressure (with my fingers) into their hip flexors, which are  found about two inches to the side of their belly button….and nine times out of ten….they come screaming off my table. This tells me their hip flexors are in spasm and the continual contraction from doing leg raises is only making matters worse.

 

Leg raises are OK, as long as your starting point begins with your legs bent at the waist (90 degrees) and pull your legs up about twenty degrees and than back down to 90 degrees. You don’t want to lower it past that starting point, otherwise you are using your hip flexors to pull them back up to 90 degrees and we don’t need to be making those muscles any tighter.

 

 

When you do a leg raise the first 90 degrees of the leg raise is activating the hip flexors….when you go past 90 degrees, the abdominal muscles begin to contract and are responsible for raising the legs any further. Unfortunately most people do there leg raises within that first 90 degrees of range of motion, which is only going to make them susceptible to low back pain. 

 

It doesn’t matter if you bend your knees, or put your hands behind your back. The muscles responsible for raising your legs those first 90 degrees are your hip flexors, NOT your abs. So don’t put your client’s health or your financial security at risk by making them do an exercise that could injure them and prevent them from continuing as a client.

 

I know people have been promoting leg raises for years, but when you look and understand the basic bio-mechanics of how the muscles work, you will see why they don’t target the muscles we think. Go grab you’re A & P book and take a look at where these muscles attach to better see what we are talking about. 

 

Next time we’ll talk about some great aerobic exercises that are weak for adding shape and tone.