The effect of breathing exercises and auricular vagus nerve stimulation on the autonomic nervous system

Transcutaneous auricular vagus nerve stimulation provides direct vagal modulation. Breathing exercises provide vagal modulation by stimulating arterial baroreceptors. In our study, it was aimed to compare these two methods with similar effects. 88 healthy volunteer participants aged 18-35 years were randomly divided into two groups as breathing exercise (Group S) and vagus stimulation (Group V). Thoracic expansion exercise was performed on the breathing exercise group. In the vagus stimulation group, stimulation was applied to both ears with a pulse width of 300 microseconds, a frequency of 10 Hz, and biphasic stimulation for 20 minutes. Autonomic measurements and pulmonary function tests were completed before and after the 10-session application to both groups. While checking heart rate, systolic blood pressure (SBP), diastolic blood pressure (DBP), RMSSD, PNN50, LF/HF, LF POWER, HF POWER values as autonomic measurements; respiratory functions were evaluated with the variables FEV1, FVC and FEV1/FVC. In the results between the groups, while the heart rate decreased significantly in both groups; Significant superiority was found in the S group compared to the V group. There was a statistically significant decrease in blood pressure values in both groups. While RMSSD, PNN50 and HF values increased significantly more in the V group; LF value decreased significantly more in the S group. When the LF/HF value was examined, a statistically significant decrease was found in the S group. In the pulmonary function test results, FEV1 value increased significantly in both groups. A significant increase in FVC value was observed in both groups, but the S group was superior. There was no significant superiority between the two groups in terms of FEV1/FVC values. As a result of all these, it was concluded that vagus stimulation is superior to respiratory exercise in increasing the parasympathetic system, and respiratory exercises are superior to vagus stimulation in reducing sympathetic activity and partially increasing respiratory functions.