On “Increasing muscle extensibility…” Weppler CH, Magnusson SP. Phys Ther. 2010;90:438–449.

This perspective article¹ was very interesting and thought provoking; however, I was slightly skeptical about your conclusions in the section on neuromuscular relaxation. Specifically, I am having trouble reconciling my clinical experience with your suggestion that an increase in extensibility during a contract-relax procedure is due to a change in sensation. I acknowledge that an examiner's perception can be misleading; however, I would be surprised if I were unwittingly applying more tension to gain more length (ie, the analog of the postintervention plot in Figure 2 of your article).

In particular, I regularly carry out contract-relax stretching on the piriformis muscle, which as I am sure you are aware, frequently becomes painful to palpation and shows increased tension in many instances of lumbosacral/pelvic dysfunction. Changes in passive medial (internal) rotation of 10 degrees or more can be obtained quite easily and without forcing the situation—most definitely counterproductive for most patients. It seems as though a shift of the tension/length graph must have taken place to the right; to achieve the same degree of thigh medial rotation as before treatment does appear to me to take less effort. Do you think this empirical observation can be rationalized in terms of the fact that the patients were symptomatic, as you note that the cited studies were carried out mostly in patients who were asymptomatic?

• © 2010 American Physical Therapy Association