Tachycardia and bradycardia are two unique names for heart rate. Specifically, tachycardia and bradycardia mean heart rates above and below the normal range accordingly. You should https://www.webmd.boots.com/heart-disease/features/heart-rate-health>know you heart rate as it is the truest indicator of health. The normal range of heart rate is between 60 beats to 100 beats per minute in a normal rest condition. If the heart rate is more than 100 per minute in a resting condition in adults (age 15 years and above), it is referred to as tachycardia. In the case of newborns, the normal heart rate is 160 beats per minute, and anything above is tachycardia. Some of the common causes of this ailment are atrial flutter, fear, anxiety, pain, infection and nicotine intake. On the other end of monitoring, the heart rate is the slow heart rate condition. The normal resting threshold is 60 beats per minute. However, 50 beats per minute are considered normal. Anything below 50 beats per minute is considered as Bradycardia. However, some marathon athletes have a condition where the heartbeat is around 40 beats per minute. This is called a good condition if the heart rate is dropping during exhalation. Due to higher stroke volume, the heart is able to pump the normal quantity of blood in less number of beats.