There is a strong action of nutation at the sacroiliac joint, as the top of the sacrum “nods” forward, while leaving the iliac bones behind.

If the legs roll inward, there can be too much stretch for the inner knee and adductors. For tight students, it’s preferable to bend the knees a bit (with support) so that the stretching sensations are felt more in the bellies of the relevant muscles. Sensations of stretch occurring near the joints and muscles attachments are indicators that nothing useful is likely to result from the stretch.