Pain in the low back is something that at least 70% of my clients complain about. And it is one of the most misunderstood conditions. It is easier to explain if I use the proper names for the muscles. Please don’t let the names scare you. They just describe where they are, and since all muscle names are in Latin, they look imposing. They aren’t. The muscles are erector spinae, and the iliopsoas, which is called simply the psoas (pronounced “so-as”).
The erector spinae muscles are a large grouping of three separate muscles all closely placed together. Some originate on the ribs, others originate on the entire length of the spine, on each vertebra, and they all cause us to stand up from a bent position, or to be able to twist and turn our trunk. The psoas originates on the lumbar (low back) vertebrae, it goes forward (behind your intestines), goes inside the bowl of your hips, and then inserts into the front of the femur – your thigh bone.
The psoas muscle pulls you down, so you can touch the floor, and the erector spinae pull you back up to standing again. The psoas also is instrumental in you lifting your leg to take a step, or pedal a bike.Let’s spend a few minutes describing the location and action of each of these muscles. Cross your arms so your hands are back-to-back, with your fingers touching and pointing at the ceiling. Your left hand (which is now on your right) will be erector spinae, and your right hand (which is now on your left) will be psoas.
When you bend over to touch the floor the psoas contracts, and you are pulled over. Try it with your hands to demonstrate. Keep the back of the hands together and fold your right fingers down toward your palm. You can imagine the opposing muscle (erector spinae) needing to stretch to be able to do this move. When you stand back up straight, erector spinae contracts and psoas needs to relax. To demonstrate that movement pull the fingers of your left hand up straight, and have your right hand follow.