The effects of bolus volume and consistency on amplitude and duration of muscle activity during swallowing in adults

Results of this investigation support previous studies which found that bolus volume and consistency significantly affect average duration and amplitude of muscle activity during swallowing m adults. Electromyographic (EMG) activity from submental (SM) and laryngeal strap muscles (LSM) was recorded as participants swallowed boluses that varied m volume and consistency. Participants in this study included ten adult females (mean age=22.6 years). Methodological differences between this study and previous physiological investigations included the use of six different food and barium consistencies (water, pudding, cheese paste, Cheenos®, barium liquid and barium paste)m addition to five different bolus volumes (1, 3, 5, 10, and 20 ml).

Regarding bolus consistency, findings of this investigation indicated that average duration of SM and LSM activity increased significantly when participants swallowed pudding,cheese paste and barium paste and Cheerios® when compared to water For bolus volume, significant increases in average duration ofSM and LSM activity occurred when participants swallowed boluses of 20 ml compared to boluses of1 ml. Similarly,average amplitude of muscle activity during swallowing was significantly affected by bolus volume and consistency,however the effects of bolus consistency depended upon the muscle involved. Average amplitude ofSM activity increased significantly when participants swallowed: 1) pudding, cheese paste, Cheenos®,barium liquid, and barium paste consistencies compared to water, 2) cheese paste only compared to water, and for barium paste compared to barium liquid. Average amplitude of LSM activity increased significantly when participants swallowed pudding, cheese paste and barium paste when compared to water, and for swallows of thick paste compared to barium liquid. Regarding bolus volume, significant increases in the average amplitude of SM and LSM activity occurred when participants swallowed boluses of 20 ml compared to boluses of 1, 3, and 5 ml.

Currently, bolus volume and consistency are not controlled or standardized when performing swallowing evaluations (as in a modified barium swallow study) or during treatment of swallowing disorders. Results of this investigation indicate that muscle activity is not consistent across volumes and consistencies presented in this study These findings support the adoption of standardized measures for bolus volume and consistency for use during swallowing evaluations and treatment of swallowing disorders.