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Heart Health: How Does Heart Rate Change with Exercise?

Difficulty
Time Required Short (2-5 days)
Prerequisites Must be able to exercise vigorously
Material Availability Readily available
Cost Very Low (under $20)
Safety No issues

Abstract

Your heart starts beating before you are born and keeps right on going through your whole life. Over an average lifetime, the human heart beats more than 2.5 billion times. Keeping your heart healthy means eating right, not smoking, and getting regular exercise. Which of your favorite physical activities give your heart the best workout and help keep it fit? Find out with this science project!

Objective

To measure your average heart rate during different types of physical activities.

Credits

Andrew Olson, Ph.D., Science Buddies

Cite This Page

MLA Style

Science Buddies Staff. "Heart Health: How Does Heart Rate Change with Exercise?" Science Buddies. Science Buddies, 30 June 2014. Web. 21 Oct. 2014 <http://www.sciencebuddies.org/science-fair-projects/project_ideas/Sports_p006.shtml>

APA Style

Science Buddies Staff. (2014, June 30). Heart Health: How Does Heart Rate Change with Exercise?. Retrieved October 21, 2014 from http://www.sciencebuddies.org/science-fair-projects/project_ideas/Sports_p006.shtml

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Last edit date: 2014-06-30

Introduction

An average-sized adult has about 5.5 liters of blood in their body, which the heart circulates about three times every minute. Your heart is constantly beating—even before birth!—to keep the blood circulating. The heart of an average 65-year-old person has contracted more than 2.5 billion times. That is a lot of heartbeats! You can see a picture of a real human heart in Figure 1, below.



A human heart (picture taken during an autopsy).
Figure 1. A human heart.


Experts on cardiac health tell us 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. Heart rate is a measure of how many times a person's heart beats in a minute (technically measured in beats per minute, or bpm). 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 bpm minus your age. For example, if you are 30 years old, your maximum heart rate would be 190 bpm (since 220 minus 30 equals 190). The American Heart Association recommends that you do exercise that increases your heart rate to between 50 and 85% of your maximum heart rate. This range is your target heart rate zone. They recommend getting at least 30 minutes of moderate to vigorous exercise most days (or a total of about 150 minutes a week).

What is your resting heart rate? What types of exercises work to elevate your heart rate? How do you feel when your heart is working at 50% of its maximum rate? How about when it is working at 75% of its maximum rate? This science project will help you answer all of these questions, and help you find fun activities that are good for your heart.

Terms and Concepts

  • Heart rate
  • Maximum heart rate
  • Target heart rate zone
  • Pulse
  • Resting heart rate

Questions

  • What is the average maximum heart rate for someone your age?
  • What is the range recommended for heart rate during exercise?
  • How much exercise does your body need each week for good cardiovascular health?
  • As an advanced challenge, do some research on aerobic exercise and anaerobic exercise. What are some examples of activities that provide these types of exercise?

Bibliography

This NOVA website has information on how the heart works and amazing heart facts:

For help creating graphs, try this website:

Materials and Equipment

  • Clock or timer that shows seconds or a helper with a watch
  • Comfortable exercise clothes
  • Simple and fun exercise equipment. You will want to do at least three different types of exercises, but not all of them may require equipment. Some equipment you may need includes:
    • Jump rope
    • Bicycle
    • Hula-hoop
    • 1-kg weight
  • Lab notebook
  • Graph paper or a graphing program

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Experimental Procedure

Measuring Your Heart Rate

  1. Use the first two fingers of one hand to feel your radial pulse on the opposite wrist, as shown in Figure 2. You will find it on the "thumb side" of your wrist, just below the base of your hand. Practice finding your pulse until you can do it quickly. Note: Do not use your thumb, because it has its own pulse, which could throw off your count.


How to find your radial pulse image
Figure 2. The photo shows how to feel your radial pulse.


  1. Your heart rate is the number of beats per minute, but you do not have to count for a full minute to get an accurate heart rate. Counting the number of beats in either 10 or 15 seconds is fine. As practice, right now use a clock or timer to time your count, and write down the number of beats you counted in your lab notebook. Then calculate the number of beats per minute (bpm) to get your heart rate. If you counted for ten seconds what do you need to multiply by to get the number of beats per minute? How about if you counted for 15 seconds? That is it!

Activity and Heart Rate

  1. Do your background research and make sure that you are knowledgeable about the terms, concepts, and questions in the Background section.
  2. Measure your resting heart rate and record it in your lab notebook, along with the date and time of the measurement. Your resting heart rate is your heart rate when you are awake but relaxed, such as when you have been sitting still for several minutes.
    1. Tip: It is best to take your resting heart rate at the beginning of the day, right after you have woken up but before you have gotten out of bed.
    2. It is a good idea to do this several times, and at different times of day, so that you can get a reliable average. You will also get an idea of the normal range of variation for your resting heart rate.
    3. If you want, you can calculate how many times your heart beats during a day, a month, and a year, based on your resting heart rate.
  3. You will be measuring your heart rate during different types of physical activity. Choose at least three different types of activities that you enjoy doing or that you think would be good exercises. You may want to choose at least one activity that you consider to be easy, and one that you think requires more energy to do. You can see some examples in Table 1.
    1. How do you think doing each activity will affect your heart rate? Do you think the activities will affect your heart rate differently?
Activity Time
0 (rest) 1 min 2 min 5 min 10 min 15 min
  beats
10 s
bpm beats
10 s
bpm beats
10 s
bpm beats
10 s
bpm beats
10 s
bpm beats
10 s
bpm
Jumping rope                        
Lifting a 1 kg weight                        
Riding a bicycle                        
Walking                        
etc.                        

Table 1. In your lab notebook, make a data table like this one to record your data. List the activities that you actually choose to do. When you do each activity, record the number of beats you count in 10 seconds (s). Later you will calculate the beats per minute (bpm) from this.

  1. Choose which activity you want to do first. Before starting it, make sure you have been resting for a few minutes and measure your resting heart rate. Your measured resting heart rate should be similar to what you measured in step 2.
  2. Perform the activity for 15 minutes. In your data table, write down the number of beats you count in 10 seconds at the times indicated in Table 1 (after 1, 2, 5, 10, and 15 minutes of activity).
    1. Once you are done with the activity, also record in your lab notebook how you felt when you finished.
  3. Calculate your heart rate after 1, 2, 5, 10, and 15 minutes of activity by multiplying the number of beats you counted (in 10 seconds) by six. This is your heart rate in beats per minute (bpm).
  4. Repeat steps 4–6 for at least two more different activities.
    1. Leave enough time between activities so that your heart rate returns to around its normal resting level.
    2. It may take more than one day to make measurements for all of the activities you want to try, so be sure to plan ahead so that you have enough time to collect data.
  5. Make line graphs of heart rate (on the y-axis, in bpm) vs. time (on the x-axis, in minutes) for each activity. Use graph paper, a spreadsheet program (like Excel), or Create a Graph. Compare the graphs.

Questions

  1. Which activity increased your heart rate the most (highest peak)?
  2. Which activity increased your heart rate the fastest (greatest slope)?
  3. Which activities elevated your heart rate to the target heart rate zone (50-85% of maximum heart rate, where your maximum heart rate is 220 bpm minus your age)?
  4. Do you notice any consistent patterns in your heart rate graphs?

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Variations

  • How does heart rate change with body position? Measure your heart rate while lying down, while sitting down, and while standing. What happens to your heart rate when standing on your hands?! (Rest your feet against a wall for balance, and have a helper find your pulse and measure your heart rate.)
  • Repeat this experiment with more volunteers. How much variation is there among heart rates of different people? How do their heart rates generally change with different types of exercise?
  • How does your heart rate change when you vary the intensity of your exercise? For this study, you will need to figure out ways to measure the intensity of your workout for the different activities. For many activities, you could use a helper with a timer to count your exercise rate. For example, your helper could count the number of jumps (or lifts, or steps) per minute (a metronome, if you have one, could also help you to keep time). If your bike has a speedometer, you can keep track of your speed. If you have access to a gym, most aerobic fitness equipment has a readout of intensity in either kcal/hour or watts, and indicators to let you see how much effort you are making as you work out. Pick two or three different levels (easy, medium, and challenging) and measure your heart rate after 5, 10, and 15 minutes of working out at that level. Do not exceed your recommended target heart rate zone while exercising (nearly 85% of your maximum heart rate). What intensity level elevates your heart rate to 50% of its maximum heart rate for each type of exercise? What intensity level elevates your heart rate to 85% of maximum?
  • For another Science Buddies project on exercise physiology, see: Effects of Exercise: Changes in Carbon Dioxide Output.

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