Do you suffer from back pain??.. Your Quadrates Lumborum could be the culprit. The function of the QL is to flex the spine laterally, extend the lumbar spine and this muscle also helps us with breathing. If we have weak lower erector spinae muscles the QL will take up the role of stability, but what is happening today due to poor posture, we are creating excessive anterior tilt of our pelvis, (which is often caused by too much sitting in front of the computer) the QL muscles are on constant contraction which leads to overuse and reduced blood flow to the area. If we are repeatedly restricting the movement of these muscles we can develop adhesions in the surrounding fascia, which in turn will lead to muscle spasms. Our posture is so important when it comes to reducing pain and dysfunction, everything we do, we should be considering our posture first.
If you have lower back pain try using a foam roller on the QL to help restore the blood flow but remember to also release the front of the hip. A great exercise to help strengthen the QL is what I call a suitcase walk or lunge as this exercise makes us use the QL to uptake the un-balance created by only having one weight at the side.
A great way to stretch the QL is to lie sideways over a stability ball.
Try some of these suggestions and see if you can start to improve your back health.