Reciprocal inhibition, psoas, agonist antagonist

http://blog.corewalking.com/reciprocal-inhibition/  pooas is a back body muscle   pulley

he psoas acts as a pulley system in the body; the hip bone is the pulley and the psoas in the rope. The  pulley system allows the psoas to help the spine stay upright on top of the pelvis. It does this through the magic of reciprocal inhibition which allows the spinal muscles (erector spinea) to extend and lengthen up the back when the psoas tones in the front as it crosses the pelvis.

The back body part is how the psoas manages to work like a pulley. It attaches on the back half of the inner thigh, comes forward to cross over the pelvis before moving backwards again to attach on the outside of the lumbar spine. It attaches at its top and bottom in the back plane of the body. The point where it crosses the pelvis is in the front plane of the body which creates the ability for the psoas to act as a pulley.

http://www.bandhayoga.com/keys_recip.html  agonist antagonist

http://blog.corewalking.com/reciprocal-inhibition/   reciprocal inhibition