PhysioOsteoGram on Instagram: "VAGAL TONE (VAGUS NERVE) STIMULATION & HRV-TRAINING Vagal tone is activity of the vagus nerve, the 10th cranial nerve and a fundamental component of the parasympathetic branch of the autonomic nervous system. This branch of the nervous system is not under conscious control and is largely responsible for the regulation of several body compartments at rest as you know from my previous post. Heart Rate Variability (HRV) Training with the Fascia-ReleaZer® by @Blackroll