Cardiac muscle is also an involuntary muscle. (Do you need to tell your heart to beat?) It is a specialised kind of muscle found only within the heart. This muscle pumps blood through the body. The average person’s heart beats more than 4,000 times in an hour (figuring on an average of 70 beats per minute), so, by time you turn 70, your heart will beat some two-and-a-half billion times. Cardiac muscle, like smooth muscle, does not tire.