a heart trick

Every man knows ties are uncomfortable. This is because stretch receptors in the carotid bodies in the upper neck sense changes in blood pressure and give false indications when they are pressured by neck ties. 

If you have ever actually experienced high blood pressure, you know its not something you want to deal with for long. Many times high blood pressure can occur after strenuous activity, as the veins are constricted to allow blood to more readily perfuse the active tissues and cardiac output increases as a result of increased heart rate. One way to cope with this is to blow slowly blow on your thumb. The vagus nerve which innervated the heart pacemaker cells is inhibited by slow rhythmic breathing and by thumb sensory.