Woman performing a yoga pose. If you suffer from regular backache but can’t seem to find any relief from back stretches, the root of the problem could lie elsewhere. According to yoga instructor Imogen Smith, tight hamstrings could be the culprit. “When your hamstrings are tight, they can pull the pelvis down and under, and create a posterior tilt to the pelvis,” says Smith. This change in pelvis position puts extra stress on the spine.