Oh My Aching Back
It could it be caused by the SI Joint

The sacroiliac joints (SI) link your pelvis and lower spine. They're made up of the sacrum - the bony structure above your tailbone and below your lower vertebrae - and the top part (ilium) of your pelvis. There are sacroiliac joints in both the right and left sides of your lower back. Strong ligaments hold these joints in place. The sacroiliac joints support the weight of your upper body when you stand. 

While it is not clear how the pain is caused, it is thought that an alteration in the normal joint motion may be the culprit that causes sacroiliac pain. This source of pain can be caused by either:

1.  Too much movement - hypermobility or instability. The pain is typically felt in the lower back and/or hip and may radiate into the groin area.

2.  Too little movement - hypomobility or fixation. The pain is typically felt on one side of the low back or buttocks, and can radiate down the leg. The pain usually remains above the knee, but at times pain can extend to the ankle or foot. The pain is similar to sciatica, or pain that radiates down the sciatic nerve and is caused by a radiculopathy.

This condition is generally more common in young and middle age women.

Pilates Tips for Strengthening the SI Joint and Psoas Muscles.

Pilates is a fantastic way to learn how to deal with SI Joint pain as it works to correct muscle imbalances that we have inflicted on our body through years of abuse. Twisting incorrectly, poor posture, trauma, injuries, etc. can all wreak havoc on our bodies over time.

Pilates exercises for SI Joint and psoas pain should include both the stretching of the muscles in the lower back and strengthening the muscles that support the pelvic floor, deep, and lower abdominal. In other words, we need to help them learn stabilization, as these muscles are our "powerhouse", providing stability for the SI Joint and the whole lumbar-pelvic girdle.

The first focus for SI Joint pain - a neutral spine

Work to stabilize your pelvis (hips), including the sacrum in proper alignment. It is important not to do these exercises in poor pelvic alignment, as you will be trying to stabilize the faulty posture which may have caused the problem in the first place! Try practicing some of the exercises below (which can be done anywhere) to help improve your posture:

1.  Sitting: When sitting in a chair press your bottom right up against the back of the chair then stack the rest of your spine up over it. Feel your ears over shoulders, over your hip bones and your breastbone should be right over the pubic bone. Navel drawn in gently. Feel space between your ribs and pelvis (lumbar spine). Proper posture is the best way to reduce tension from sitting at work all day, on computers, driving, etc.

2.  Lying down: A pelvic tilt or spine articulation is a great way to stretch, lengthen, and strengthen your core. Lying on a mat with your knees bent and feet hip width apart. Begin by taking an inhale and then exhale and roll off your tailbone, imprint your back, and roll all the way up to the base of your shoulder blades. Take another inhale and exhale and slowly, lay your spine back down on the mat, one vertebra at a time.

3.  Standing: With your back up against a wall stand with your buttocks and shoulder blades leaning into the wall. Notice whether your lower back is against the wall or if there is an excessive arch there. The latter is more common. To achieve neutral keep the buttocks and shoulders against the wall and then draw (or imprint) the lower back into the wall. You should feel the abdominal muscles engage and/or the ribs drawing in. Release and repeat to flex your lumbar spine.

Always consult your doctor to assess sacroiliac joint pain and choose appropriate exercises for you.