Sweaty Science: How Does Heart Rate Change with Exercise?
Have you ever wondered how many times your heart beats in a year, or will beat throughout your life? Over an average lifetime, the human heart beats more than 2.5 billion times. For a person to keep their heart healthy, they should eat right, not smoke, and get regular exercise. In this science activity, you’ll measure your heart rate during different types of physical activities to find out which give your heart the best workout to help keep it fit.
This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,200 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.
A 150-pound adult has about 5.5 liters of blood in their body on average, which the heart circulates about three times every minute. A person’s heart is constantly beating to keep the blood circulating. Cardiac health experts say that the best ways to keep our hearts healthy are through a balanced diet, avoiding smoking, and regular exercise.
Exercise that is good for your heart should elevate your heart rate. But by how much, for how long and how often should your heart rate be elevated? This has to do with how fit you are and your maximum heart rate, which is 220 beats per minute (bpm) minus your age. For example, if you are 30 years old, your maximum heart rate would be 190 bpm. The American Heart Association (AHA) recommends doing exercise that increases a person’s heart rate to between 50 to 85% of their maximum heart rate. This range is called the target heart rate zone. The AHA recommends a person gets at least 30 minutes of moderate to vigorous exercise (that elevates their heart rate to the target heart rate zone) on most days of the week, or a total of about 150 minutes a week.
Extra: Try this activity again but test different physical exercises. How does your heart rate change when you do other exercises? How are the changes similar, and how are they different?
Extra: Measure your heart rate while lying down, while sitting down, and while standing. How does your heart rate change with body position?
Extra: Repeat this activity with other volunteers. How does their heart rate compare to yours? How does their change in heart rate while exercising compare to how yours changed?
Extra: Try this activity again but vary the intensity of your exercise. What intensity level elevates your heart rate to 50% of its maximum heart rate? What about nearly 85% of its maximum? Be sure not to exceed your recommended target heart rate zone while exercising!
Observations and Results
After just a minute of exercise, did you see your heart rate reach its target heart rate zone? Did it initially jump higher for a more strenuous exercise, like hula-hooping, compared to a more moderately intense exercise, such as walking?
If you did a moderately intense exercise, such as walking, you may have seen an initial jump in your heart rate (such as putting your heart rate within the lower end of your target heart rate zone within about one minute of exercise), but then your heart rate only slowly increased after that. After 15 minutes, you may have reached the middle of your target heart rate zone. To reach the upper end, people usually need to do a moderately intense exercise for a longer amount of time (such as for 30 minutes). If you did a more strenuous exercise, such as hula-hooping, you may have seen a higher initial bump in your heart rate (such as reaching the middle of your target heart rate zone after just one minute of exercise), and then your heart rate stayed about the same for the remaining 14 minutes of exercise. Overall, doing a more strenuous exercise generally raises a person’s heart rate faster compared to doing an exercise that is only moderately intense.
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Teisha Rowland, PhD, Science Buddies
Science Buddies |
The heart, heart rate, health, exercise
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