The spine is comprised of four curves: cervical, thoracic, lumbar and sacral.
The four curves are designed to form the S curve of the spine. If the curve is distorted, the discs take the pressure of misalignment and the nerves extending out from where the distortion occurs are compressed, effecting the body parts attached to that nerve.
Yoga poses are meant to train the body to be healthy and supple. Consistent practice and application will result in improved posture, and an increased sense of balance, with head, shoulders and pelvis in proper alignment. Additionally, unlike many other forms of exercise, yoga for seniors helps stretch and strengthens both sides of the body equally.
Proper body alignment and good posture, which helps maintain the natural curvature of the spine, is an important part of reducing or avoiding back pain.