Throughout development from infancy to adulthood, normal vital signs change. Due to anatomical differences, what is normal for one age group could be abnormal for another. Normal pulse rate changes substantially from infancy to middle childhood. By age 12, the normal pulse rate approximates that of an adult.
Normal Pulse Rates Vary
Pulse rates, like other vital signs, fall within a wide range because they change frequently in response to the body's needs. For example, your child's pulse rate will typically be higher while digesting a meal than while he's asleep. A normal resting pulse rate range for a 12-year-old is 50 to 100 beats per minute. This will remain the normal range throughout adolescence and adulthood.
Regular exercise is important to keep your 12-year-old's heart and body healthy. To benefit the heart, exercise must be vigorous enough to push the pulse into a target range. For example, a 12-year-old with a resting pulse of 75 will derive heart benefits from a pulse rate of approximately 135 to 180 beats per minute during exercise, notes the text "Fitness for Life: Middle School." The range varies slightly according to your child's resting pulse rate. Sometimes, during extremely strenuous activity, the pulse rate may rise even higher.
Cause for Concern
In a 12-year-old, a resting pulse rate greater than 100 or less than 50 could be a cause for concern. Fever, dehydration, accidental medication overdose and many other things can affect the pulse rate. If you are concerned that your child may have an abnormal pulse rate, consult your doctor. If your child has an abnormal pulse rate with breathing difficulty or lightheadedness, call 911.