Pistol shooters in competition slow their heart rate. Oddly, to get the sight-picture they need, the weapon is often held at arms length and the pulse can clearly be seen on the tip of the barrel. Minute, but it's there. I could calm mine, but it was claimed one chap stopped his heart during the last fraction of the pull. I seem to remember he was wired as a medical curiosity, not by the shooting fraternity.