Since birth to the moment it stops your heart works inexhaustibly. In your life time your heart ticks more than two and a half billion times without a moment of rest. Assessing your heart rate, at which your heart beats, is a useful and easy way to evaluate how hard also your heart works at any given time. Your heart works harder and faster during exercising to cope with muscle demand for blood and oxygen. The faster it beats the more intensive the physical activity is. If you, during physical exercise, chart your heart rate you could have a very good way of monitoring the intensity level of your exercise.
