Is a tight Quadratus Lumborum the reason for your lower back ache? I don't know! What's my Quadratus Lumborum (QL)? is probably your answer to that question.
Well the QL is a muscle that lies deep in your trunk. It is located posteriorly in the lower back and you have one on each side of your spine. It attaches to your bottom rib, the transverse processes of the lumbar spine, and the top edge of the hip (the iliac crest). It's main function is to stabilise and move the spine and pelvis. When both sides contract it extends the spine and when the muscle is only activated on one side, the trunk is bent towards that direction (lateral flexion). When the QL becomes tight or overworked, it can lead to lower back ache or go into spasm.
Stretch for the QL
Take the feet as wide as is comfortable
Flex into a forward fold, taking the hands to the floor. Keep the legs as lengthened as you can without locking out the knees.
Place both hands under your right foot.
Keeping both hands securely under the right foot, take your weight over onto the left leg pushing the hip to the left. Keep the hips facing forward and watch the left hip doesn't rotate round towards the front.
Repeat on the other side.
Please note: the flexion element of this stretch makes it unsuitable for anyone with disc issues or osteoporosis.