The Effect of Auricular Vagus Nerve Stimulation and Controlled Breathing Exercises on Performance and Autonomic Nervous System

The sympathetic and parasympathetic divisions of the autonomic nervous system affect the function of many organs, glands, and involuntary muscles in the body. The sympathetic and parasympathetic nervous systems often play opposing roles in the body, one is suppressed when the other increases activity. With the beginning of exercise or sports activity, sympathetic activity in the body increases and after a certain period reaches a plateau value at maximum activity. With the end of sports activity, the suppressed parasympathetic activity increases, and the sympathetic system returns to its resting state over time. Low sympathetic activity and/or high parasympathetic activity and low heart rate before training or exercise can be considered as performance indicators. It also indicates that recovery from the previous training or exercise is adequate. Parasympathetic system activation continues for up to 48 hours after exercise. If the exercise is intense and persistent, parasympathetic system activity can last up to 72 hours. In addition, due to the increase in anaerobic respiratory rate during exercise, there may be decreases in parasympathetic reactivation. Transcutaneous vagus nerve stimulation (VNS) can affect cardiovascular parameters both at rest and during exercise. VNS improves autonomic modulation and positively reduces pain and fatigue associated with cycling exercise. On the other hand, VNS is particularly useful in reducing pain and fatigue during and after competition. Slow breathing modulates the activity of the vagus nerve. Controlled breathing exercises (CBE) directly affect the respiratory rate, which can lead to faster physiological and psychological calming effects by increasing vagal tone during slow expiration. CBE increase heart rate variability in healthy participants. The investigators aim to contribute to the literature by examining the effects of VNS and CBE on performance and the autonomic nervous system in moderately physically active individuals and their superiority over each other.