2011 Volume 15 Issue 1 Pages 25-30
[Objective] To obtain basic information on postural adjustment during swallowing by investigating the effects of the height of tables on which the forearms are placed during swallowing on the activity of the suprahyoid muscles.
[Methods] A total of 10 healthy volunteers swallowed porridge (5 g) under the following three conditions: without a table (both arms hanging by side), and with the forearms resting on a table where the distance between the table surface and sitting surface was either one third of the sitting height (Condition A) or one third of the sitting height plus 15 cm (Condition B). During swallowing, surface electromyography of the suprahyoid muscles was performed, difficulty of swallowing was subjectively assessed, and the elevation angle of the shoulder girdle was measured. The duration of muscle activity during swallowing, muscle activity integral, and the time from the start of swallowing to maximum muscle activity were calculated based on the surface electromyography of the suprahyoid muscles. The assessment and measurement items for the conditions with a table were normalized using the condition without a table as a standard, and the rates of change from the condition without a table were calculated (% muscle activity time, % muscle activity integral, % time to maximum muscle activity, and % subjective difficulty of swallowing). Comparisons of assessment and measurement items among the three conditions, the elevation angle of the shoulder girdle between the two conditions with a table, and the rates of change in assessment and measurement items from the condition without a table were performed using the Wilcoxon signed rank sum test.
[Results] Compared to the condition without a table, Condition A had a significantly shorter muscle activity time and time to maximum muscle activity of the suprahyoid muscles and a significantly lower muscle activity integral and subjective difficulty of swallowing, but no significant differences were observed for Condition B. Compared to Condition B, Condition A had a significantly higher elevation angle of the shoulder girdle and a significantly lower % muscle activity time, % muscle activity integral, % time to maximum muscle activity, and % subjective difficulty of swallowing.
[Conclusion] The present findings suggest that the height of the table on which the forearms are placed during swallowing affects the activity of the suprahyoid muscles. Appropriate adjustment of this height, along with postural adjustment of the neck and trunk, may therefore be a useful component of postural adjustment during swallowing.
