The airway smooth muscle (ASM) plays an important role in the mechanism of respiratory system. Asthma, a common respiratory disease is associated with ASM hyper-contraction and shortening of airway diameter. This results in occlusion of the airway lumen leading to breathing difficulties. Various studies have shown that ASM can be relaxed by length oscillations. Previous experiments on ASM by applying sinusoidal oscillation at low frequencies and high amplitudes have showed a clear reduction in active force. Similar tests for a larger frequency range on ASM have also shown large reduction in dynamic force. But, it is not well known what parameters induce relaxation the most on ASM. The purpose of our research is to see the degree of relaxation when superimposed oscillations are applied on breathing and see which parameter relaxes smooth muscle the most.

This research also focuses on investigating the effect of pulse oscillation rather than sinusoidal oscillation on contracted ASM. Isolated ASM were tested using pulse oscillations with wide range of frequency, amplitude and duration. Results obtained from these experiments showed that pulse oscillation with short duration had significant effect on the relaxation of ASM compared to sinusoidal oscillations with longer duration.