Changes

Resting Heart Rate (HR_rest) is how fast your heart beats when you are not expending any energy beyond simply being alive. Finding your HR_rest is easy; just check your heart rate while sitting still or lying down. Early morning is a good time, before any exercise or taken caffeine[[Caffeine]], both of which will raise your HR_rest. A low HR_rest is normally a sign of fitness, as endurance training tends to increase the size of your heart, and a large heart needs to beat less often to pump the same amount of blood. HR_rest is used to calculate [[Heart Rate Reserve]]. (Sometimes Resting Heart Rate is called Basal Heart Rate or HR_b.)