Higher activity in subjects without competent lips implies a higher muscular effort due to the requirement of lip sealing during functional activities. Hyoid muscular activity was not modified by the presence or absence of lip competence.

Objective: This cross-sectional study evaluates the electromyographic (EMG) activity of lips and anterior temporalis muscles of children with competent or incompetent lips. Study design: Forty children were classified clinically according to their lip competence into two groups of 20 each: 1) competent lips group (CLG), and 2) incompetent lips group (ILG). Surface EMG activity of the superior orbicularis oris (SOO), inferior orbicularis oris (IOO), and anterior temporalis (AT) muscles was recorded with the children seated in the upright position during the following tasks: 1) at rest; 2) speaking; 3) swallowing; 4) puffing out the cheeks. Results: ILG showed lower EMG activity than CLG in the SOO and IOO muscles at rest, similar activity in both muscles during speaking, similar activity in the SOO muscle and lower in the IOO during swallowing. ILG showed significantly higher activity than CLG in both muscles while puffing out the cheeks. In the AT muscle, ILG showed lower activity than CLG at rest, during speaking and swallowing, whereas activity was similar while puffing out the cheeks. Conclusion: The difference in EMG activity recorded in children with incompetent lips and with competent lips suggests that the status of their musculature could affect the position and stability of their upper/lower anterior teeth.

Objective To compare the effect of breathing type on electromyographic (EMG) activity of respiratory muscles during tooth clenching at different decubitus positions. Methods Forty young men participants were included, 11 with upper costal, 9 with mixed, and 20 with costo-diaphragmatic breathing type. EMG recordings of diaphragm (DIA), external intercostal (EIC), sternocleidomastoid (SCM), and latissimus dorsi (LAT) muscles during tooth clenching in the intercuspal position were performed in dorsal, left lateral, and ventral decubitus positions. Results DIA EMG activity was higher in subjects with upper costal or mixed than with costodiaphragmatic breathing type (p = 0.006; 0.021, respectively), whereas it was similar between upper costal and mixed breathing types. EIC, SCM, and LAT activity was similar among breathing types. Conclusion Higher DIA activity would be a risk factor to exceed the adaptive capability of healthy subjects with upper costal or mixed breathing type.

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This study aimed to compare the electromyographic (EMG) activity among participants with costo-diaphragmatic, mixed or upper costal breathing type. Forty male were classified according to their breathing type into three groups: costo-diaphragmatic, upper costal and mixed breathing type. EMG activity of diaphragm (DIA), external intercostal (EIC), sternocleidomastoid (SCM) and latissimus dorsi (LAT) muscles was recorded in the dorsal, left lateral and ventral decubitus positions, during the following tasks: 1) quiet breathing, 2) speaking, 3) swallowing, and 4) sustained maximal inspiration. DIA activity was higher in upper costal than in costo-diaphragmatic breathing in all tasks and body positions; was higher in mixed than in costo-diaphragmatic breathing in all tasks in the dorsal and ventral decubitus positions and only in task 4 in the left lateral decubitus position; was similar between upper costal and mixed breathing in all tasks and body positions. EIC activity was significantly higher in mixed than costodiaphragmatic breathing in all tasks in the dorsal decubitus position and only in task 4 in the left lateral decubitus position. SCM activity did not show significant differences. LAT activity was only higher in upper costal than costodiaphragmatic breathing in task 4 in the dorsal decubitus position, in tasks 1, 2 and 4 in the left lateral decubitus position, and in tasks 2, 3 and 4 in the ventral decubitus position. EMG activity of the DIA was the only muscle that allows to differentiate between upper costal or mixed breathing than costo-diaphragmatic in all tasks in the dorsal and ventral decubitus positions.