Influence of Chewing Process on Respiratory Sinus Arrhythmia

Respiratory sinus arrhythmia (RSA) is a clockwise fluctuation in heart rate at the frequency of the respiratory cycle. RSA is an important homeostatic mechanism, the parameters of which change under various conditions - from stress to physical exercise. However, the direct effect of chewing, the most common form of muscle activity, on RSA has not yet been studied. We studied the dynamic evolution of RSA and the associated heart rate and respiratory rate during the transition from rest to chewing gum in 37 students (15 men). The measure of RSA in this study was the spectral power of high-frequency HF oscillations. Chewing was accompanied by a slight increase in respiratory rate (RR) and a significant increase in heart rate (HR), but a statistically insignificant increase in the HR/HR ratio. Although respiration was an important determinant of RSA in this study, we observed a significant decrease in HF in the presence of relatively stable RR and HR/RR levels, indicating that the main driver of the evolution of RSA during mastication is an increase in sympathetic tone due to the trigeminal reflex.