Unlike most workers, the heart never gets time off. Each hour, an average heart pumps about 75 gallons of blood throughout your body. Even more difficult, during exercise the heart must work overtime. The heart is the pump that causes your blood to circulate throughout your body and to all of your cells. The heart makes sure that the oxygen you breathe, the nutrients from the food you eat, and the water you drink, is delivered to your body. Without the heart, each of your organs would not be able to function!
When you exercise, you increase the demands for energy and gas exchange. Therefore, your heart must increase the speed at which the blood delivers the vital nutrients. How hard is your heart willing to work? In this investigation, you will examine how much your heart rate will increase and the amount of time it takes for your heart to return to its normal rate.
Collect Resting Pulse Rate Data
A pulse is the vibrations created each time your heart pumps blood through your arteries. The rate of your pulse indicates the speed of your heart pumping. Find a large tendon on the underside of your wrist. Using your middle and ring finger from your other hand, locate your pulse just below the base of the thumb and on the outside of the large tendon.
1. Find your resting pulse rate before you exercise. Count the beats in your pulse for 30 seconds, then multiply that number by 2 to find the number of beats per minute. Repeat the step two more times, and average your results. Record your results in Table 1.
2. Post your results in the D2L course discussion board and collect data from the discussion board for two other students.
Table 1: Rate of pulse when resting
Student Name
Self
Student 1
Student 2
Trial 1
Trial 2
Trial 3
Average
Collect Pulse Rate Data after Exercise
1. Transfer the average resting pulse rate data to the chart below.
2. Do 100 jumping jacks in a row without stopping. After you stop, immediately take your pulse for 30 seconds. Multiple that number by 2 to get your pulse per minute.
3. Without exercising again, continue to take you pulse for the next ten minutes. This will determine how quickly your heart returns to its resting rate. Record the results after each minute in Table 2
4. Post your results in the D2L course discussion board and collect data from the discussion board from four other students.
Table 2: Rate of pulse after exercise for ten minutes
Student Name
Self
Student 1
Student 2
Resting Rate (Table 1)
Immediately after Exercise
1 minute after
2 minutes after
3 minutes after
4 minutes after
5 minutes after
6 minutes after
7 minutes after
8 minutes after
9 minutes after
10 minutes after
Data Analysis & Conclusions
Set up the information from Table 2 onto a graph. You can either:
· create a graph in Word/Excel
· graph using this site: https://nces.ed.gov/nceskids/createAgraph/.
· draw one by hand (see next page for graph paper).
1. Write the time variable on the x-axis. This is the independent (manipulated) variable.
2. Write the dependent (what you are measuring) variable on the y-axis.
3. Write the title in the format of dependent variable vs. independent variable.
4. You will place the data for all 3 individuals from Table 2 on the same graph.
· Approximately, how many minutes did it take your heart to return to its normal rate?
· Approximately, how many minutes did it take the other students’ hearts to return to their normal rate?
· How did your data compare to other students in the course?
· What might contribute to the differences in resting heart rate and the time it takes to return to resting heat rate between individuals?
· What else, besides exercise, might speed up your heart rate? Give two examples.
· Why does your heart rate increase when you exercise? Be specific (hint: think about what needs to be transported to your muscle cells while they are being used).