One of the benefits of many forward bending Yoga poses is expanding and stretching of the hamstring muscles. Therefore, it is ideal to take time in our Yoga classes to align the sit bones and leg bones so we can target the proper line of stretch of the hamstring muscles. With this alignment, we should understand the basic anatomy and mechanics of the various hamstring muscles.
In Janu Sirsasana and many other Yoga Forward Bend Poses, we explore the expansion of the hamstring muscles. The resistance of the hamstrings against the sit bones (ischial tuberosities) limits the motion of the pelvis structure in relation to the thigh bone, thus reducing the amount of forward bending motion we can generate at the hip joint. By applying the principal of reciprocal inhibition in our Yoga practice, we can manipulate the neural signals of key muscle groups to more effectively relax the hamstrings and to increase our ability to fold into our yoga forward bend poses.