“Views on exercise maintenance…” Swärdh E, Biguet G, Opava CH. Phys Ther. 2008;88:1049-1060

Lastly, we are confused by Halili’s suggestion that the type of movement involved in puckering and blowing actions differs in that puckering involves active movement of the orbicularis oris muscle, whereas blowing involves a holding contraction. First, Halili’s classifi cation of the type of movement in blowing—“the orbicularis oris is held in more of an isotonic contraction”—is confusing because the defi nition of an isotonic contraction is a contraction in which tension increases and the muscle changes length (eg, movement). The change in length can either be shortening, as in a concentric contraction in which the tension produced exceeds the resistance, or lengthening, as in an eccentric contraction in which the resistance exceeds the tension produced. The movements that we requested patients to demonstrate and the movements that we recorded from start to full excursion of the action were the usual acts of performing puckering and blowing, in which the orbicularis oris muscle shortens and the lips protrude. Given that blowing involves movement of the lips associated with a shortening contraction of the orbicularis oris muscle, we do not fi nd Halili’s second explanation reasonable in understanding the results reported or an acceptable challenge to our interpretation. The statement that, when treating patients with synkinesis, “...synkinesis is more easily integrated...when the primary mover...is in isotonic contraction rather than actually moving” is inaccurate as written and is not congruent with our clinical and research experience with patients with facial movement disorders. Karen L Schmidt, Rachel L Denlinger, Jessie M VanSwearingen, Jeffrey F Cohn