Spontaneous Muscle Release Technique (SMRT) SMRT is a positional release modality. The principles of SMRT are similar to Strain Counterstrain and PRT. When we use SMRT, we move the tissue or body part into a position of ease or comfort. In other words, if tissue is shortened, we shorten it further. What we believe is happening when we do passively move tissue into its existing pattern is described in a theory called Proprioceptive Theory.