When the iliopsoas gets into a shortened state, also known as ‘locked short,’ it will take the pelvis into an anterior tilt. The ASIS (the bony bump on the front of your hips) will lower down towards the ground. The hamstrings will get overstretched, or ‘locked long.’ There will be an increase in lordosis in the lumbar spine, which will, in turn, affect the alignment of the whole spine and can cause both forward head posture and pain between the shoulder blades. In this structural pattern, the abdominals are often pushed forward and weak. (Sometimes short piriformis is part of this pattern as well, but more about that some other time.)
Two of the primary causes of a locked short psoas are (a) sitting for long periods of time or (b) over exercising and not stretching properly. Proper core strength is also important for a balanced psoas, so weak abdominal muscles as well as weak back extensor muscles contribute to this dysfunctional low-back pattern. In the following clip we will see the location of psoas and an explanation of why it can cause low back pain.