One may use Padahastasana (the hands-to-feet pose) in scope of working with strained muscles of the legs’ rear surface and the lower back. Very often people coming to practice yoga suffer from this problem, and hence comes the value of this asana for many of those practicing.
Subject to the asana correct performance – i.e., the smooth, even stretch of the entire rear surface of the body, from the tailbone to the crown – the following muscles shall be worked out through stretching: the lumbar extensors and the knee-bending muscles (the biceps muscle of the thigh, on the figure below it is shown as the rear thigh muscles group); the quadriceps thigh muscle involved in the knee unbending shall be toned. The relations between these groups of muscles shall come to harmony. It is interesting that this effect complies with the concept of A.G. Safronov, the authority in yoga and philosophy, concerning the energetic mechanism of the asanas’ influence upon human organism (“Yoga: Philosophy, Psychosomatics, Bioenergetics”) and with the concept on muscles’ coordination developed by N. A. Bernstein, an outstanding Soviet neurophysiologist (“On Coordination and Regulation of Movements”, “Essays On Physiology of Movements and Physiology of Human Activity”).
The effect resulting from the asana is the profound workout of the said zone and the reflex therapeutic influence upon the urogenital system.
However the complete downward bending shall be impossible if one has a very stiff lower back and pelvic zone.
Sometimes fitness instructors recommend that in order to reduce the tension from the asana one should have one’s knees bent, without stretching the legs and slightly stretching the lower back zone. This shall entail a completely opposite result – the lower back muscles shall become even more constrained.
Why does it happen this way?
Because in scope of such performance mode the muscles that were supposed to be worked out through stretching (here you can read more about the mechanism of the muscles’ workout in asanas), that is, the biceps muscles of the thigh, shall be now actively working and thus subject to excess tension.
In terms of this the muscle tension of the lower back extensors and iliac-psoas muscle shall reflexory increase, and it will aggravate the problem even further.
In addition to this, the antagonist muscles shall also contract due to their incomplete flexion. The performance of asana in such a mode does not provide for harmonization of the listed muscles group.
In order to approach the performance of Padahastasana correctly it would be wise to supplement one’s complex with preparatory asanas – the Vakrasana, the twisted Vakrasana (the body is twisted towards the knee lying on the floor), the Ardha Uttanasana (the standing half forward bend).
The pumping postures should be applied after the stretching ones, and in scope of this the following asanas shall be proper from physiological and energetic points: Chaturanga dandasana, Purvottanasana, Kandharasana, Parivrtta Chaturangasana.