Students take each other's pulses
at rest and after exercise to determine recovery times.
Students will be able to:
- same-sized slips of paper, one for each student
- copy of the "Matters of the Heart" student handout
- copy of the "Data Sheet" student handout
- copy of the "Plotting Your Results" student handout
- clock or timer with seconds
fitness can be determined by tests, including those designed to measure heart
rate during exercise, the volume of oxygen consumed while exercising at maximum
capacity (known as VO2 max), body fat percentage, muscle fitness,
flexibility, and heart recovery rate.
recovery rate is the time it takes for the heart to return to its normal
resting beat. A healthy heart will return quickly to its normal beat after
exercising. Heart recovery rates can be improved by making lifestyle changes,
such as eating a healthy diet, not smoking, and exercising regularly.
resting heart rate values for different ages are:
newborn infants: 100 to 160 beats per minute
children 1 to 10 years: 70 to
120 beats per minute
children over 10 and adults
(including seniors): 60 to 100 beats per minute
Athletes can have much lower resting
heart rates, as low as 40 to 60 beats per minute.
this activity, students take each other's pulses at rest and after
exercise to determine recovery times.
Begin by asking students the
question: "What does heart rate have to do with fitness?" (Students
may suggest that a
slower heart rate would indicate that the heart is more efficient and has to
work less to pump blood.)
Organize students into pairs and
distribute the student handouts to each student. Review the activity with
Have students take their resting
pulse rates. It is very
important that students master the technique of taking their pulse and obtain
consistent values before doing the exercises. A slight variation is expected in
pulse rate but readings should be within three to five beats per minute during
the resting rate calculation. (If taking the pulse for 15 seconds is not
generating consistent results, have students take 30-second readings and
multiply their values by two.) If students still have problems, you may want to
show them how to measure the pulse at the carotid artery in the neck. Whatever
method students choose, they should use that method for the entire experiment.
Have students average the three
resting rate trials and multiply the average by four to determine resting heart
rate per minute. Pass out small slips of paper. Have students write their average
resting heart rate per minute on their slip and hand it back in. Write the
heart rates on the board (without identifying the students) and ask students
what might cause any variability in resting heart rates. (Resting heart
rates vary with age, sex, physical shape, and cardiovascular condition. Resting
rates can also vary due to emotional changes, caffeine intake, and medication
side effects. Athletes generally have lower resting pulse rates than
non-athletes.) As a
class, analyze the data set for high, low, average, and median values. (You may
want to have students collect data from a similar number of adults for
Before each team does its jumping
jacks, emphasize to students that when they collect heart-rate data it is
important that they collect their data at exactly one-minute intervals after
the initial pulse measurement (0) is taken at the moment the jumping jacks are
done. Explain to students that each minute includes the time that they are
counting the heartbeats.
Instruct each team to conduct the
exercise and pulse-measuring portion of the activity. If students are having
difficulty measuring a pulse rate, suggest that they find the pulse a few
seconds before they have to start counting.
As a class, determine the range for
the y-axis of the
"Recovery Time" graph. The range should include the highest heart
rate per minute among students as well as the lowest heart rate per minute
(including resting heart rates, which will also be plotted). All students
should use the same range when plotting their results.
Have students do the exercise and
plot their results. Collect the graphing sheets and choose a few of the slopes
from the "Recovery Time" graph (including the highest and lowest)
to plot on the board to show the range of results among class members. Discuss
with students what the different slopes mean and how recovery rate is connected
to fitness. To conclude, discuss what ways recovery rates could be improved.
To illustrate other ways to evaluate fitness, show students the
portion of the program at right (3:55) that presents how doctors measure body
composition and maximum oxygen consumption (VO2 max) and animates
how the body consumes oxygen.
After students have viewed the video,
ask them to explain how someone with an ideal body weight can still be
considered unfit. (Weight is only one measure of fitness. A person with an
ideal body weight may still have a poor lean-to-fat ratio. While fat is
necessary for body metabolism, more than 25 percent fat in men and more than 30
percent in women is considered unhealthful.)
As an extension, have students test
for muscle fatigue. Have students open and close a clothespin for 20 seconds.
Then have them rest for a few seconds and do another 20-second-long set. How
long does it take before muscle fatigue sets in? Have students research and
write a one-page report on what causes muscle fatigue.
Students with heart or respiratory conditions should not do the exercises.
During the recovery period, the heart is pumping blood to the
muscles. Oxygen and carbon dioxide are being exchanged in the lungs and the
muscles. Immediately after exercise, a high demand is placed on the
cardiovascular system to provide oxygen and remove carbon dioxide from the
muscles being exercised. The pulse rate should be highest right after exercise.
As time progresses, more and more blood will be pumped to the muscles
exchanging oxygen and carbon dioxide. Over time, the levels of oxygen in the
muscle will return to normal and the CO2 formed during exercise will
be removed. At this point, a normal resting pulse rate will return.
estimation of the physical fitness of an individual can be made based on the
amount of time required to return to a resting pulse rate. An athlete with an
efficient cardiovascular system will return to resting rate in a shorter period
of time that someone whose heart muscle and pumping volume are inefficient.
Student Handout Questions
What are some of the factors that influence resting pulse rate? Why might an
athlete have a lower pulse rate than a person who does not exercise regularly? A variety of factors can influence pulse rate, including
physical condition, age, weight, heart disease, medications, smoking, and
emotional state such as stress. In general, pulse rates will be lower in those
who exercise and are in good physical condition. (Exercise increases the
strength of the heart muscle. A stronger heart muscle pumps more efficiently,
i.e., more blood pumped per pulse beat. As a result, the number of beats
[pulses] required to move the same amount of blood through the body is
decreased. In addition, exercise increases the number of capillaries in muscle.
This provides more channels to transport oxygen and carbon dioxide during
exercise. The result is that gas exchange in both the lungs and the muscles is
faster. This, in turn, reduces demand on the heart to pump faster.) Weight also
influences pulse rate. The heart must pump harder to move the blood through
more body tissue, in this case mostly fatty tissue. This extra tissue places a
demand on the circulatory system for oxygen and nutrients. To compensate the
heart must pump faster increasing the pulse rate. Additionally, the amount of
blood in the arteries increases, often leading to higher blood pressure.
In the "Recovery Time" graph, describe the changes that occurred to
your heartbeat in minutes 1–7. Use specific numbers from the data table
in your response. Answers will vary.
If you compared the
graph of an extremely fit athlete with the graph of a sedentary 50-year-old
individual, would you expect them to be alike or different? Explain your
reasoning. You would expect the extremely fit athlete to return to resting
heart rate more quickly, as indicated by a steep slope on the graph. This would
likely be due to the athlete having a stronger cardiovascular system.
What effect could a longer pulse recovery period have on a person's
ability to perform certain activities? What effect could a shorter pulse
recovery period have? A longer pulse recovery time
would limit the type of endurance activity a person could undertake. Endurance
events, such as a marathon, provide a continual demand on the cardiovascular
system. If oxygen levels are not replaced and carbon dioxide is not removed in
muscles, the muscle cells will move into anaerobic respiration, an inefficient
state that eventually leads to cramping and muscle fatigue. A shorter pulse
recovery time indicates an efficient cardiovascular system. Gas exchange
between lungs and muscles is efficient and therefore muscles can function for
an extended period of time without moving into anaerobic respiration. This
person likely will not become cramped or fatigued as quickly and will be able
endure more prolonged exercise.
What might a person do to improve his or her recovery period? A person could exercise, which would strengthen the
heart muscle, increase its efficiency, increase elasticity in blood vessels,
and increase capillary supply to muscles.
Features profiles of Team NOVA members, four of the
runners' diaries, a training calendar, information about how exercise affects
the body, tips for rookie runners, and more.
facts on heart rate and the structure of the heart.
Map of the Human Heart
Shows blood flow through the heart and
diagrams heart structures.
Researchers Find Heart Rate
Worth a Thousand Words
Explains heart rate recovery and how it
can be improved.
Essentials of Human Anatomy
by Elaine Nicpon Marieb. Redwood
City, Calif.: Benjamin Cummings Publishing Inc., 1994.
Provides basic chemistry of the human body and an overview of all
Human Body: An Illustrated Guide to Its Structure, Function, and Disorders
by Charles B. Clayman, MD. London,
New York: DK Publishing, 1995.
medical drawings and images from diagnostic technologies to help explain the
body's anatomy, function, and common disorders.
The "Matters of the Heart" activity aligns with the following National
Science Education Standards (see
Science in Personal and Social
Science in Personal and Social
Understanding personal and community
Classroom Activity Author
Fred Sculco taught science for 35
years, including courses in biology, environmental science, genetic
engineering, and alternative energy resources. In addition to his middle- and
high-school teaching experience, Sculco has worked as a consultant for the
National Institutes of Health, the U.S. Department of Energy, and the
Massachusetts Audubon Society.