2002 Volume 6 Issue 1 Pages 49-55
Objectives： The button-pull exercise is one of the strategies employed to stimulate the lip closing function for patients suffering from dysphagia caused by failure of the lip function． The purpose of this study was to examine the relationship between orbicularis oris muscle activity and the peak force of pulling a plate out of the lips in relation to the size of the plate．
Methods： Five normal persons were employed as subjects．Eight plates of different size (two vertical dimensions × four horizontal dimensions) with the same thickness (3 mm) were manufactured on a custom-made basis for each subject with plaster casts secured individually so that each plate could be inserted within the mucolabial folds．Each subject was instructed to hold each plate with the lips closed．The electromyographic activity of the orbicularis oris muscles of the lower and the upper lips was recorded starting with the onset of plate traction until each plate was pulled out． Peak force was also recorded in association with EMG using a tension gauge when the plate was pulled out of the lips． Smoothed peak EMG activity was measured at 0.1 second intervals for 2 seconds until the plate was pulled out．
Results： Peak force was increased in accordance with the increase in plate size irrespective of its vertical or horizontal size．However， the change in muscle activity was variable across subjects．
Conclusion： It was suggested that the button-pull exercise for lip closure training should be intended not to increase the peak traction force by increasing the plate size but to improve proprioception of lip closure． In other words， use of the button-pull exercise to stimulate the lip closure function should be based on electromyography and the direction of muscle contraction．
