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ECG AND HEART
FUNCTION
ECG AND
EXERCISE
Instructor Terry Wiseth
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Start Your Lab
What Do I Need To
Hand In For This Lab?
1) ECG Tracing Data Table At Rest
2) ECG Tracing Data Table After Exercise
3) Labeled Sketch of ECG Tracing At Rest
4) Labeled Sketch of ECG Tracing After Exercise
5) Answers to Questions 1-8
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You can use the links below to print off the
data tables, graphs and questions you will
need to hand in with this lab.
ECG Data Table
At Rest
After Exercise
ECG Tracing Graph Paper
(You will want 2 copies of this)
Questions 1-8
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Click
on the
The
electrocardiogram
(ECG) can be
blackboard
a
monitoredtoinview
the laboratory
and gives
larger
blackboard.
information
on the electrical activity of the
atria and ventricles during the cardiac
cycle.
mV
sec
sec
sec
Time
DATA
ACQUISITION
UNIT
Power
Monitor
Stimulator
Outputs
Recording
Inputs
+
1
-
2
Start Recording
Stop Recording
ECG
Sensor
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The cardiac cycle consists of a contraction
of the atria and then the ventricles, followed
by a period of rest. An impulse from the
sinoatrial node produces a contraction of
the atria and then excites the ventricles via
the atrioventricular node.
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The currents produced by these impulses
are recorded as the electrocardiogram or
ECG, and the various waves can be
correlated with the contractions of the atria
and ventricles. An ECG is also called an
EKG or electrokardiogram.
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We can summarize an ECG tracing in the
image below. Each of the waves or spikes
on the tracing can be represented with
letters to indicate changes in electrical
actions within the heart.
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It is easy to monitor a subjects
electrocardiogram (ECG) in the lab and
determine any changes provoked by
exercise. In this lab the intervals between
the various components of the ECG are
measured from a volunteer at REST and
immediately after EXERCISE, when the heart
rate is elevated. The results will help to see
how changes in physical activity affect heart
function.
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Exercise increases the cardiac output by
increasing 1) stroke volume and 2) heart
rate. This lab compares the ECG from a
volunteer at rest and during recovery from
exercise. This is achieved by measuring the
P-Q, Q-T and R-R time intervals and the
QRS Complex amplitude to see which are
affected by exercise. Study the image below
to identify the various parts of the ECG
R
tracing.
Click on the
P
PQ
Ventricular
Contraction
Q
S
Atrial
Contraction
QT
QRS Complex
Amplitude
T
Image or here
to view a
printable
image
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The PQ Interval represents the atrial
contraction. The length in time of the PQ
interval can infer the strength of the atrial
contraction. The QT Interval represents the
contraction and relaxation of the ventricles.
The length in time of the QT Interval can
infer the strength of the ventricular
contraciton.
R
P
PQ
Ventricular
Contraction
Q
QRS Complex
Amplitude
T
Click on the
Image or here
to view a
printable
image
S
Atrial
Contraction
QT
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During exercise there is an increase in the
amount of blood circulating around the
body. Activation of the sympathetic nervous
system increases cardiac output by
modifying heart function in two ways:
1) The Stroke Volume Increases
2) The Heart Rate Increases
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1) The Stroke Volume Increases
The volume of blood in the heart before
contraction increases and the volume of the
blood in the heart after contraction
decreases. Thus the Stroke Volume (the
amount of blood ejected from either
ventricle during each cardiac cycle)
increases because there is more blood in
the ventricles before contraction and less
remaining in the ventricles after contraction.
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Comparisons of Stroke Volumes can be
inferred by the relative amplitude of the QRS
complex of an ECG tracing at rest and after
exercise.
Amplitude is measured in millivolts (mV)
and can be found on the vertical axis of the
ECG tracing. A larger amplitude (mV)
reading would indicate a more forceful
ventricular contraction. A more forceful
ventricular contraction causes more blood
to be ejected during a cardiac cycle and
thus an increased Stroke Volume.
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A measure of Stroke Volume can be inferred
by the amplitude of the QRS complex of an
ECG tracing.
Amplitude
mV
sec
sec
sec
Time
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2) The Heart Rate Increases
The number of cardiac cycles (contractions)
per minute increases. The heart rate
increase is a result of the excess CO2
produced by exercising muscles.
AT REST
mV
One contraction each second
would represent a heart rate of 60
beats per minute
sec
sec
Time
sec
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ECG
Spikes
mV
sec
sec
Time
sec
The image to the
left is a tracing of
an ECG reading.
The spikes can
be thought to
represent one
heart beat. From
the tracing given
here we can see
that there is a
spike every
second.
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ECG
Spikes
mV
sec
sec
Time
sec
A spike each
second would
represent a heart
rate of 60 beats
per minute. As
well, a spike
every 0.5
seconds would
represent a heart
rate of 120 beats
per minute.
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mV
sec
sec
sec
Time
DATA
ACQUISITION
UNIT
Power
Monitor
Stimulator
Outputs
Recording
Inputs
+
1
-
2
Start Recording
Stop Recording
ZOOM
PRINT
ECG
Sensor
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During this experiment you will
display an ECG from a
volunteer at rest and during
recovery from exercise. To
Start click the Red power
control button to turn on the
Data Acquisition Unit.
mV
sec
sec
sec
Time
DATA
ACQUISITION
UNIT
Power
Monitor
Stimulator
Outputs
Recording
Inputs
+
1
-
2
Start Recording
Stop Recording
ZOOM
PRINT
ECG
Sensor
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Click on the Blue lead from the
ECG Sensor to plug it into
Recording Input #1. The Red,
Green and Black sensors on
the table are radio telemetry
sensors and will relay signals
to the ECG Sensor.
mV
sec
sec
sec
Time
DATA
ACQUISITION
UNIT
Power
Monitor
Stimulator
Outputs
Recording
Inputs
+
1
-
2
Start Recording
Stop Recording
ZOOM
PRINT
ECG
Sensor
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Click on the Red electrode to
connect it to the left wrist of
the volunteer. Next click on the
Green and Black electrodes to
place them on the right foot
and the right wrist
respectively.
You should click on the
STOP RECORDING
button at this time
mV
sec
sec
sec
Time
DATA
ACQUISITION
UNIT
Power
Monitor
Stimulator
Outputs
Recording
Inputs
+
1
-
2
Start Recording
Stop Recording
ZOOM
PRINT
ECG
Sensor
At Rest
Start Recording the ECG
waves by clicking on the Green
button on the monitor. The ECG
tracings will continue for about
40 seconds and will then stop.
You should click on the Red
button to stop recording.
R
P
QRS Complex
Amplitude
Ventricular
Contraction
PQ
T
Q
S
Atrial
Contraction
mV
QT
sec
sec
sec
Time
DATA
ACQUISITION
UNIT
Power
Monitor
Stimulator
Outputs
Recording
Inputs
+
1
-
2
Start Recording
Stop Recording
ZOOM
PRINT
ECG
Sensor
When you have collected
all of the data for the
subject at rest
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Part 2 of the Lab
Click on the blue ZOOM button
above to see a larger view of the
ECG. Click on the yellow PRINT
button view a printable version.
Enter your data in the Data Table
for At Rest.
mV
sec
sec
sec
Time
Monitor
DATA
ACQUISITION
UNIT
Power
Stimulator
Outputs
Recording
Inputs
+
1
-
2
Start Recording
Stop Recording
ZOOM
PRINT
ECG
Sensor
You will be notified what to do next,
The exercise is now complete.
when the subject has exercised the
Click Here to go to the
prescribed time. Please be patient.
next slide to collect data
We will now have the subject
exercise by running in place for
a prescribed period of time.
Click on the subject above to
begin exercising. When the
exercise is completed we will
monitor the ECG once again.
R
P
Ventricular
Contraction
QRS Complex
Amplitude
T
PQ
Q
S
AtrialYou should
click on the
Contraction
STOP RECORDING
QT
button at this time
mV
sec
sec
sec
Time
DATA
ACQUISITION
UNIT
Power
Monitor
Stimulator
Outputs
Recording
Inputs
+
1
-
2
Start Recording
Stop Recording
ZOOM
PRINT
ECG
Sensor
After Exercise
Start Recording the ECG
waves by clicking on the Green
button on the monitor. The ECG
tracings will continue for about
40 seconds and will then stop.
You should click on the Red
button to stop recording.
PERFORM THE FOLLOWING SKETCHES
1) Sketch an image of the ECG tracing taken from
the subject at Rest. Include at least three cycles
in your sketch. Label the PQRST landmarks of
one of the cycles.
ECG TRACING PAPER
2) Sketch an image of the ECG tracing taken from
the subject after Exercise. Include at least three
cycles in your sketch. Label the PQRST
landmarks of one of the cycles.
ECG TRACING PAPER
Click Here to
View a Printable ECG
Graph Paper
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Answer The Following Questions
1) Which component of the ECG coincides with contraction of the
ventricles?
2) Which component of the ECG coincides with contraction of the
atria?
3) What is the heart rate of the subject at rest?
4) What is the heart rate of the subject after exercise?
5) Describe at least two differences between the ECG tracings of the
subject at rest and after exercise.
6) Why is the amplitude of the ECG tracing of the subject after
exercise higher than when measured at rest?
7) Tachycardia is a term used to indicate a rapid heart rate. Which of
the two ECG tracings performed indicate tachycardia?
8) Sinus rhythm is a term used to describe normal heart rate. Which
of the two ECG tracings performed indicate sinus rhythm?
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View a Printable Version
of the Questions
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You have now collected the data you
need to finish the lab. Be sure that you
include the following in your lab
report. You can click on each of the
following to link to them.
1) ECG Tracing Data Table At Rest
2) ECG Tracing Data Table After Exercise
3) Labeled Sketch of ECG Tracing At Rest
4) Labeled Sketch of ECG Tracing After Exercise
5) Answers to Questions 1-8
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End the Lab
Click to View a
Printable Version
of blank ECG
Tracing Paper
1.5
1.0
Click to View a
Printable Version
of this Image
mV
0.5
0
Click to View
ECG Data
Table at Rest
sec
Time
sec
sec
Monitor
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Return to Last
Slide Viewed
Sketch the ECG tracing above. You can use the red link shown above to print out
a blank ECG tracing graph. Using the time measuring bars and the mV scale on
the left, find the time intervals for the following: R-R Interval, P-Q Interval, Q-T
Interval, Amplitude of QRS Complex.
ECG Tracings
Data Table at REST
Time
Amplitude
seconds
mV
Heart Rate
HR = 60 / RR Interval
RR Interval
PQ Interval
QT Interval
QRS Amplitude
Click to View a Printable
Version of the ECG
Data Table at Rest
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Return to Lab
After entering the data from the ECG tracing calculate
the Heart Rate at REST by using the formula given in the
table.
Click to View a
Printable Version
of ECG
Tracing Paper
1.5
1.0
Click to View a
Printable Version
of this Image
mV
0.5
Click to View
ECG Data
Table After
Exercise
0
sec
Time
sec
sec
Monitor
Click Here to
Return to Last
Slide Viewed
Sketch the ECG tracing above. You can use the link shown above to print
out a blank ECG tracing graph. Using the time measuring bars and the mV
scale on the left, find the time intervals for the following: R-R Interval, P-Q
Interval, Q-T Interval, Amplitude of QRS Complex.
ECG Tracings
Data Table After Exercise
Time
Amplitude
seconds
mV
Heart Rate
HR = 60 / RR Interval
RR Interval
PQ Interval
QT Interval
QRS Amplitude
Click to View a Printable
Version of the ECG
Data Table After Exercise
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Return to Lab
After entering the data from the ECG tracing calculate
the Heart Rate after EXERCISE by using the formula
given in the table.