Name
-------------------.----------
Date
How Does Exercise
Affect Heart Rate?
-
39-1
LAB
INVESTIGATION
~
The heart pumps blood to all the cells of the body. As you exercise,
the muscle cells use more oxygen and food, which must be
replenished. The cells also produce more wastes, which must be
removed. The heart responds to the changing needs of body cells
by pumping harder.
OBJECTIVES
• Determine your heart rate by taking your
pulse.
• Hypothesize the effect of exercise on heart
rate.
• Compare your heart rate during rest and
during exercise.
MATERIALS
stopwatch or clock with second hand
ROCEDURE
Part A. Resting Pulse
Figure 1.
1. Locate your pulse by placing your index and
middle fingers on the carotid artery. This artery
is located in your neck, under the corner of
your jaw. Figure 1 shows the position your
fingers should be in.
2. Press your fingers lightly against your neck fo
feel the pulse. Each pulse of blood is caused by
one beat of the heart.
3. Work in pairs. Your partner will be the
timekeeper. You will be the experimental
subject.
4. Sit quietly for 2 minutes.
5. Count your pulse for 15 seconds, and record
this number in Table 1.
6. Repeat step 5 twice more.
7. Calculate your heart rate per minute by
multiplying each of the 15-second counts by 4.
8. Calculate your average resting heart rate per
minute.
9. Make a hypothesis to explain how exercise will
affect heart rate. Write your hypothesis in the
space provided
Part B. Exercise
1. Follow your teacher's instructions for
exercising. Remember that whatever exercise
you do should be done at a steady rate
throughout all exercise periods.
2. You will exercise for 30 seconds of each minute
for 10 minutes. In between exercise periods,
you will count your pulse for 15 seconds and
record ,this count in Table 2. Figure 2 shows
that each minute should be divided as follows.
a. 30 seconds--exercise
b. 5 seconds--Iocate the pulse
c. 15 seconds--count the pulse
d. 10 seconds--record the count and prepare
to exercise again
. ""
245
figure 3.
Figure 2.
I
Exercise
I
Part C. Recovery
Recovery
Part D. Graphing
1. Immediately after you finish the exercise
period, sit down and begin the procedure for
counting your pulse as you recover from
exercising.
2. You will count your pulse twice each minute
for 10 minutes. Each count lasts 15 seconds.
Figure 3 shows that each minute should be
divided as follows.
a. 15 seconds--count the pulse
b. 15 seconds--record the count and prepare
for the next count
c. 15 secondsncount the pulse
d. 15 seconds--record the count and prepare
for the next count
All counts should be recorded in Table 2.
1. Look at the grid provided in Data and Observations. The minutes are on the horizontal axis.
The heart rates are on the verticle axis.
Plot your average resting heart rate on the first
vertical line.
2. Plot your heart rates during exercise for
minutes 1 through 10.
3. Plot your recovery pulse rates for minutes 11to
20. NOTE: There are data for every thirty
seconds in this time period Be sure to plot the
heart rate data against the correct times.
HYPOTHESIS
3. Calculate the number of beats per minute for all
counts recorded in Table 2.
DATA AND OBSERVATIONS
Table 1.
Condition
Trial
Pulse
Beats/15 seconds
Rest
Beats/minute
1
2
3
Average
.
246
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Name
_
Date
_
Table 2.
Condition
Minutes
1 20:00
11:00
,
Pulse
Beats/minute
~
.
10
2345678912:30
17:30
19:30
11:30
18:00
17:00
16:30
16:00
14:00
13:30
13:00
18:30
15:30
15:00
14:30
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100
120
140
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180
20
200
220
40
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Rest 1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20
Exercise
Return to Rest
Minutes
ANALYSIS
1. What was your average resting
heart rate?
_
_ When did this rate occur?
2. What was your highest heart rate?
3. Did you return
to your resting
4. Why do some classmates
5. Describe
return
rate during
Part C?
If so, how many minutes
to their resting rates more rapidly
did it take?
than others?
the shape of your graph.
6. What factors,
other than exercise,
would
increase heart rate?
_
CHECKING YOUR HYPOTHESIS
Was your hypothesis
supported
by your data? Why or why not?
FURTHER INVESTIGATIONS
1. Compare the average heart rate of the males with that of the
females in your class.
2. Test the effect of lying down, standing
resting heart rate.
248
up, and sitting
on your
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