Download Muscle Fatigue

Activity 15
PS-2820
Muscle Fatigue
Physiology: Muscle fatigue
Qty
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DataStudio GLX setup file: muscle.glx
Equipment and Materials
PASPORT Xplorer GLX
PASPORT Force Sensor
Timer (stopwatch or equivalent)
Rubber ball, tennis ball, or equivalent (approximately 7 cm diameter)
Part Number
PS-2002
PS-2104
SE-8702B
Purpose
The purpose of the activity is to compare muscle fatigue in hand muscles due to isotonic and
isometric exercise.
Background
Muscles convert chemical energy into a mechanical force that pulls the muscle shorter and
results in movement. All muscles work in pairs by pulling and relaxing; they cannot push.
Skeletal muscles are controlled voluntarily. They are the most
abundant tissue type in humans. Microscopic examination of this
muscle type reveals alternating bands of light and dark stripes,
which is why it is sometimes called striated muscle. These
muscles are usually attached to bones by tendons and contract
when they receive nerve impulses from the brain, allowing bones
or cartilage to move. Muscles can also connect to skin, which can
be demonstrated by executing facial expressions.
Two types of contractions are isotonic and isometric. Most muscle movement involves a
combination of both types of contractions. Isotonic (same tension) contractions are produced
when heavy objects are lifted. Most body movements use this type of contraction because the
muscle must shorten and maintain a constant tension. Isometric (same length) contractions
develop when a muscle is not allowed to shorten and the muscle tension increases. Pushing
against a fixed object and supporting body weight are two examples of isometric contractions.
Muscle fatigue is the consequence of unrelenting work performed by muscles. Under this
condition, the expected force that is necessary to maintain the activity diminishes and muscle
performance is compromised.
Pre-lab Questions
Exercise your hand muscles two different ways for equal amounts of time, and measure the grip
force of the hand after each type of muscular contraction. Compare your ‘dominant’ hand to the
other hand.
1.
How will your grip force after one minute of isotonic (same tension) contraction compare
to your grip force after one minute of isometric (same length) contraction?
2.
How will the grip force of your ‘dominant’ hand after exercise compare to the grip strength
of your other hand after exercise?
Biology with Xplorer GLX
© 2005 PASCO
p. 97
Activity 15
Muscle Fatigue
PS-2820
Safety Precautions
•
Stop data collection if the activity of squeezing becomes painful.
•
Follow all directions for using the equipment.
Procedure
GLX Setup
1.
Connect a PASPORT Force Sensor to the top of the GLX. The
Graph Screen will automatically open with Force (N) versus Time
(s).
2.
Open the GLX setup file labeled muscle.glx (see the appendix at
the end of this activity). The setup file is set so the Force Sensor
records data at 10 measurements per second.
Figure 1: Connect the sensor
Sensor Calibration (Optional)
•
See the appendix at the end of this activity.
Equipment Setup
1.
For the isotonic exercise (same tension), use a tennis ball (or a rubber ball) that you can
squeeze over and over again between the thumb and the middle two fingers of your hand.
2.
For the isometric exercise (same length), squeeze the sides of the PASPORT Force Sensor
between the thumb and the middle two fingers of your hand.
3.
Screw the rubber bumper into the front of the Force Sensor.
4.
Practice using the timer.
Record Data
•
Data recording is easier if one person records data and keeps track of the time while
another person exercises and is measured. There are three parts to data recording for each
hand.
•
Each trial of data recording and exercising will last 60 seconds (one minute).
•
When you squeeze the Force Sensor, try to maintain a force of 40 N (newtons).
Part
A
B
C
Grip Force Measurement
Before exercise, ‘dominant’ hand
After isotonic exercise, ‘dominant’ hand
After isometric exercise, ‘dominant’ hand
Grip Force Measurement
Before exercise, ‘other’ hand
After isotonic exercise, ‘other’ hand
After isometric exercise, ‘other’ hand
Part A: Grip Force Measurement Before Exercise
1.
Put the middle two fingers of your ‘dominant’ hand through the finger
holes on the back end of the PASPORT Force Sensor.
2.
Press the ZERO button on the Force Sensor and then place your thumb on
the rubber bumper.
Figure 2: Squeeze Force Sensor
Biology with Xplorer GLX
© 2005 PASCO
p. 98
Activity 15
Muscle Fatigue
PS-2820
3.
Press the Start key
on the GLX. At the same time, start the timer for 60 seconds and
begin squeezing the Force Sensor.
•
Remember; try to maintain a force of 40 N for the entire time of 60 seconds. DO NOT
squeeze with your index finger or little finger – only with your thumb on the rubber
bumper and the two middle fingers that are in the finger holes of the sensor.
4.
Stop recording data and stop squeezing after 60 seconds.
5.
Switch to your other hand and repeat the procedure.
Part B: Grip Force Measurement After Isotonic Exercise
6.
Grip a tennis ball between the middle two fingers and thumb of your
‘dominant’ hand.
7.
Start the timer for 60 seconds and begin squeezing the ball as rapidly
as possible.
•
Don’t use your index finger or little finger to ‘help’ – just use your
middle two fingers and thumb. Give your thumb a real ‘workout’.
8.
At the end of 60 seconds, quickly put the Force Sensor on
your hand as before. Press the ZERO button on the sensor
and then put your thumb on the rubber bumper.
9.
Press the Start key
on the GLX. At the same time, start the timer for 60 seconds and
begin squeezing the Force Sensor.
•
Try to maintain a force of 40 N for the entire time of 60 seconds. DO NOT squeeze with
your index finger or little finger – only with your thumb and two middle fingers.
10.
Stop recording data and stop squeezing after 60 seconds.
11.
Switch to your other hand and repeat the same procedure.
Figure 3: Isotonic exercise
Part C: Grip Force Measurement After Isometric Exercise
12.
Grip the sides of the Force Sensor between the middle two fingers
and thumb of your ‘dominant’ hand.
13.
Start the timer for 60 seconds and begin squeezing the sensor
between your middle two fingers and thumb as hard as possible.
14.
At the end of 60 seconds, quickly put the Force Sensor on your
hand as before. Press the ZERO button on the sensor and then put
your thumb on the rubber bumper.
15.
Press the Start key
on the GLX. At the same time, start the
timer for 60 seconds and begin squeezing the Force Sensor.
•
Try to maintain a force of 40 N for the entire time of 60 seconds.
16.
Stop recording data and stop squeezing after 60 seconds.
17.
Switch to your other hand and repeat the procedure.
Biology with Xplorer GLX
© 2005 PASCO
Figure 4: Isometric exercise
p. 99
Activity 15
Muscle Fatigue
PS-2820
Analysis
1.
Use the built-in analysis tools in the Graph Screen to determine the beginning grip force,
the final grip force, and the average grip force for each run of data.
2.
Record the beginning, final, and average values of grip force the Data Table.
3.
Determine if there are differences in the changes in grip force (if any) between males and
females.
Record your results in the Lab Report section.
----------------
Appendix
To open a specific GLX file, go to the home screen (press
). In the home screen, select ‘Data
Files’and press ‘Activate’ (
). Use the cursor keys to navigate to the file you want. Press F1
(
) to open the file.
Optional: To calibrate the PASPORT Force Sensor, see the instructions provided by the
instructor.
Biology with Xplorer GLX
© 2005 PASCO
p. 100
Activity 15
Muscle Fatigue
PS-2820
Lab Report - Activity 15: Muscle Fatigue
Name ________________________________ Date ___________
Pre-lab Questions
Exercise your hand muscles two different ways for equal amounts of time, and measure the grip
force of the hand after each type of muscular contraction. Compare your ‘dominant’ hand to the
other hand.
1.
How will your grip force after one minute of isotonic (same tension) contraction compare
to your grip force after one minute of isometric (same length) contraction?
2.
How will the grip force of your ‘dominant’ hand after exercise compare to the grip strength
of your other hand after exercise?
Data
Make a sketch of one run of Force versus Time,
including labels for the y- and x-axes.
Data Table
Part
Grip Force Measurement – Dominant Hand
A
Before exercise, ‘dominant’ hand
B
After isotonic exercise, ‘dominant’ hand
C
After isometric exercise, ‘dominant’ hand
Part
Grip Force Measurement – Other Hand
A
Before exercise, ‘other’ hand
B
After isotonic exercise, ‘other’ hand
C
After isometric exercise, ‘other’ hand
Biology with Xplorer GLX
Beginning
Final
Average
Beginning
43.4 N
45.6 N
52.2 N
Final
37.5 N
28.3 N
23.6 N
Average
38.9 N
34.1 N
35.4 N
© 2005 PASCO
p. 101
Activity 15
Muscle Fatigue
PS-2820
Questions
1.
What happened to your grip force after you did the exercise?
2.
How did your grip force change when you did the isotonic exercise compared to when you
did the isometric exercise?
3.
Were the results different for the dominant and the non-dominant hand after 60 seconds?
Explain.
4.
What can you determine about the rate of muscle fatigue between males and females in
your class data? Explain.
5.
Describe how your thumb and hand felt at the end of each activity.
6.
Name an activity where your body loses the ability to deliver adequate oxygen to the
muscles.
7.
Another word for “without oxygen” is: anaerobic. During this cycle of oxygen debt, what
product accumulates in the muscle tissues?
8.
Do you think that frequently used muscles would tire faster or slower than muscles that are
not used as regularly? Explain.
Biology with Xplorer GLX
© 2005 PASCO
p. 102