Cardiovascular System Science: Investigating Heart Rate Recovery Time
As Valentine’s Day approaches, we’re increasingly confronted with stylized images of the heart. Real hearts serve very important functions – a person’s heart beats to supply blood to their entire body, and the heart has to work harder when they exercise. Have you ever wondered how quickly your heart beats when you exercise, or how long it takes to recover back to its normal rate after you’re done exercising? In this science activity, you’ll get to do some exercises to explore your own heart rate recovery time.
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.
Your heart is constantly beating – even before birth! – to keep blood circulating through your body. For a person to keep their heart healthy, it’s important to exercise regularly. The American Heart Association recommends that a person does exercise that is vigorous enough to raise their heart rate to their target heart zone for at least 30 minutes on most days, or about 150 minutes a week in total. (A person’s target heart rate zone is 50% to 85% of their maximum heart rate, which is 220 beats per minute [bpm] minus their age.)
After getting some exercise, a person’s heart needs time to recover, or go back down to its normal, resting heart rate. How long it takes for the heart to return to its resting heart rate is referred to as the heart rate recovery time. In general, people who regularly exercise, and therefore are likely to have healthier hearts, have faster heart rate recovery times than people who do not regularly exercise.
Extra: Graph your results. How did your heart rate change over the course of this activity?
Extra: Try repeating this activity but compare a group of athletes to a group of non-athletes. How does the heart rate recovery time of people who are physically fit compare to people who do not regularly exercise?
Extra: Do this activity again but this time include volunteers of different ages. Does heart rate recovery time increase with age? Be sure that the volunteers you recruit can safely do the exercise!
Extra: Design an activity to compare the heart rate recovery time of people who smoke to people who don’t. Do smokers have increased heart rate recovery times compared to non-smokers?
Observations and Results
Did your heart rate quickly drop when you started resting, and then start to level out as it approached your resting heart rate? Did it reach your resting heart rate after one to seven or more minutes when you stopped exercising?
Immediately after exercising, your heart rate was likely in the upper end of its target heart rate zone. As soon as you started resting, your heart rate should have quickly decreased. Specifically, one minute after you started resting, your heart rate likely rapidly dropped, and then continued to drop, but much more slowly, as it approached your resting heart rate over the following minutes. It may have taken about one to seven or more minutes for your heart rate to go back down to your resting heart rate (after you stopped exercising). Generally, the faster a person’s heart rate recovers, or reaches their resting heart rate, the better shape they are in. Specifically, in 1999 a study was published in The New England Journal of Medicine that found that if a person’s heart rate decreases by 12 bpm or less within the first minute after exercising, it is considered abnormal and can be indicative of heart problems and a predictor of mortality. (See the link in the “More to explore” section, below, for entire study.)
More to Explore
Teisha Rowland, PhD, Science Buddies
Science Buddies |
Heart rate, exercising, the heart, cardiovascular system
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