PhysioEx Exercise 2 Activity 7
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Feb 20, 2024
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2/6/24, 1:55 PM
PhysioEx Exercise 2 Activity 7
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PhysioEx Lab Report
Exercise 2: Skeletal Muscle Physiology
Activity 7: Isotonic Contractions and the Load-Velocity Relationship
Name: Sophie Vanderkallen
Date: 6 February 2024
Session ID: session-6c0bdba4-e6eb-a9b4-8538-6e44eaaaa8d7
Pre-lab Quiz Results
You scored 100% by answering 5 out of 5 questions correctly.
Experiment Results
Predict Question
Stop & Think Question
During an isotonic concentric contraction, the
You correctly answered: force generated by the muscle is greater than the weight of the
attached load.
1
During an isotonic concentric contraction
You correctly answered: the latent period increases with heavier loads.
2
During the latent period for an isotonic concentric contraction
You correctly answered: cross bridges cycle and, when muscle tension exceeds the load,
muscle shortening occurs.
3
Muscle shortening velocity
You correctly answered: decreases with heavier loads.
4
An isotonic contraction of a muscle is one in which
You correctly answered: the length of the muscle changes.
5
Predict Question: As the load on the muscle increases
, what will happen to the latent period,
the shortening velocity, the distance that the weight moves, and the contraction duration?
Your answer: The latent period will increase, the shortening velocity will decrease, the
distance will decrease, and the contraction duration will decrease.
1
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PhysioEx Exercise 2 Activity 7
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Experiment Data
Post-lab Quiz Results
You scored 100% by answering 6 out of 6 questions correctly.
Review Sheet Results
What kind of contraction did you observe when you attached the 2.0 gram weight to the
skeletal muscle and stimulated a contraction?
You correctly answered: isometric.
1
Which of the weights allowed the fastest muscle shortening velocity?
You correctly answered: 0.5-g weight.
1
Which of the weights induced the longest latent period of the muscle contraction?
You correctly answered: 1.5-g weight.
2
Which weight did the muscle contraction move the greatest distance?
You correctly answered: 0.5-g weight.
3
Which of the weights allowed the longest duration of muscle contraction?
You correctly answered: 0.5-g weight.
4
An isotonic contraction of a muscle is one in which
You correctly answered: the length of the muscle changes.
5
When lifting a heavy load
You correctly answered: the muscle shortening velocity is decreased in comparison with
lighter loads.
6
If you were using your bicep muscles to curl a 7-kg dumbbell, when would your muscles be
contracting isotonically?
Your answer:
When your arm extends downwards to the point of it being straight (but not while it is straight) & when the arm rises from the down position back to the raised position that would be the time that muscles contract isotonically.
1
Explain why the delay between muscle stimulation and load movement became longer as
the load became heavier in the experiment. How well did the results compare with your
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PhysioEx Exercise 2 Activity 7
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prediction?
Your answer:
correct.
Explain why the shortening velocity became slower as the load became heavier in this
experiment. How well did the results compare with your prediction?
Your answer:
correct.
3
Describe how the shortening distance changed as the load became heavier in this
experiment. How well did the results compare with your prediction?
Your answer:
correct.
4
Explain why it would take you longer to perform 10 repetitions lifting a 10-kg weight than it
would to perform the same number of repetitions with a 5-kg weight.
Your answer:
With a greater load, the pace of shortening reduces, therefore the repetitions will take longer with a 10-kg weight on your shoulders.
5
Describe what would happen in the following experiment: A 2.5-g weight is attached to the
end of the isolated whole skeletal muscle used in these experiments. Simultaneously, the
muscle is maximally stimulated by 8.5 volts and
the platform supporting the weight is
removed. Will the muscle generate force? Will the muscle change length? What is the name
for this type of contraction?
Your answer:
The muscle is still going to generate force constantly as before , the muscle will still change in its length and this is an isotonic contraction type.
When the force or tension in a muscle remains constant as the length of the muscle changes/ varies, this is called an isotonic muscular contraction because muscle length change is not bound by a certain speed, it can occur at any optimal rate.
6
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