Count the Beats
Your pulse, or heartbeat, is just the sound of the valves in the heart closing. This happens as they push the blood throughout the chambers. If you listen to it through a stethoscope it sounds like, "lub-dub, lub-dub."
The beats are from the heart muscle contracting and pumping blood out of the heart. First the right and left atria contract, pumping blood to the right and left ventricles, then the ventricles contract and work together to push blood out of the heart.
The pause in between is when the heart fills up with blood again to start the process over.
Take your pulse, write down, now run in place or jump rope for one minute and check your pulse again. Your pulse will increase in order to get more oxygen to your body quicker.
Over your life time, your average pulse rate changes.
Newborns - 130
3 months - 140
6 months - 130
1 year - 120
2 years - 115
3 to 6 years- 100
8 years - 90
12 years - 80
Adults - 60 to 100 beats per minute.