Another cause of lower back pain is found in the alignment of the left and right sides of the body, some bodies are structurally asymmetrical: one leg is shorter than the other, or the pelvic halves are different sizes, people can be born that way, or their structure can be altered by bone fractures. Weakness on one side of the body can also be caused by operations, serious muscle injury, nerve injury in the spine or a stroke.
Asymmetry is also normal for everyone, because we have dominance in the eyes, hands or feet: we favour a particular side during all activities, and the favoured side is always stronger. The body is stabilised in spiral patterns, thus the left hip stabilises the right hand and the right hip stabilises the left hand, and relative differences in strength will then occur in the right and left hips. This can be enough to cause lower back pain for some, because the pelvis begins to tilt sideways – called lateral pelvic tilt. The pelvis is higher on the side of the weaker hip and lower on the stronger hip. The Iliac bones also rotate slightly forwards on one side and backwards on the other, twisting the pelvis and Scoliosis can be caused by the pelvis tilting sideways. Pain occurs without any past history of injury, leaving sufferers baffled about the causes
Left-Right imbalances need careful assessment and treatment, as well as constant monitoring- they have a tendency to come back, because movement habits can be deeply ingrained in every part of the body.
In Yoga, any asymmetrical asanas can adversely affect existing imbalances, but this is especially true of any form of lunge asanas. Because lunges are strength building they can reinforce existing strengths and weaknesses.
After treatment by a Physiotherapist or Biokineticist, Ashtangis and Vinyasa practitioners may benefit from small classes with a very strict Iyengar teacher, correct alignment needs to be taught and reinforced until it is internalised.
Kendall, McCreary, Provance, 1993, Muscles, Testing and Function
De Franca 1996, Pelvic Locomotor Dysfunction