Lauren Bozzuto
Mrs. Lynch
Anatomy and Physiology 7
13 November 2014
Muscle Fatigue Lab Activity
Abstract:
The lab was performed in order to compare the fatigue and contraction rate of skeletal muscle
compared to the fatigue and contraction of smooth muscle. In order to do this, the pulse, an
example of smooth muscle, was counted in beats per minute for one minute and a clothes pin
was opened and closed, which shows an example of skeletal muscle. These two examples were
used to show how fast smooth and skeletal muscle fatigue and also how they contract. It was
concluded that smooth muscle does not tire while skeletal muscle does, and that smooth muscle
cannot be contracted as much as skeletal muscle in a set period of time, but if contracting at the
same rate, skeletal will tire quicker.
Hypothesis:
If each muscle is contracted at the same rate, then skeletal muscle would fatigue quicker because
smooth muscle is a slow twitch muscle meaning it will not fatigue.
Materials:
o Stopwatch
o Clothes Pin
Procedure:
Procedure for finding fatigue rate of skeletal and smooth muscle:
1.) Gather all materials.
2.) Count participants pulse for 1 minute, record in data table.
3.) Using the clothes pin, squeeze it continuously at same rate as pulse until unable to
squeeze anymore and hand becomes tired.
4.) Compare rates of skeletal and smooth muscle.
5.) Repeat two more times to make sure results are accurate.
Procedure for finding contraction rate of skeletal and smooth muscle:
1.) Gather all materials.
2.) Count participants pulse for 1 minute, record in data table.
3.) Have participant squeeze clothes pin as fast as possible for 1 minute and record in data
table.
4.) Compare rates of skeletal and smooth muscle.
5.) Repeat experiment two more times to make sure results are accurate.
Data and Results:
During the lab, the participant counted the amount of beats per minute of their pulse in order to
find how much the muscle contracts and how long it takes for it to tire. A similar idea was done
to find the same information of skeletal muscle. A clothes pin was used to represent how skeletal
muscle contracts and fatigues. First, the clothes pin was squeezed at the same rate as the pulse in
order to see how long it took for the skeletal muscle to tire as compared to smooth muscle. Then,
the clothes pin was squeezed as fast as possible for one minute to compare the contraction rate of
skeletal and smooth muscle.
Fatigue Rate of Skeletal and Smooth Muscle
Type of
Contraction Rate
Time Until Fatigue
Muscle
Trials:
Trial 1
Trial 2
Trial 3
Trial 1
Trial 2
Trial 3
Smooth
60 BPM
60 BPM
60 BPM
Never
Never
Never
60/ min
60/min
60/min
1000
800
500
Muscle
Skeletal
Muscle
contractions contractions contractions
Contraction Rate of Skeletal and Smooth Muscle
Types of Muscle
Contraction Rate
Trials:
Trial 1:
Trial 2:
Trial 3:
Smooth Muscle
66 BPM
66 BPM
66 BPM
Skeletal Muscle
134/min
144/min
140/min
Conclusion:
The purpose of this lab was to determine the fatigue and contraction rate of which skeletal and
smooth muscle tire. The hypothesis that was predicted, that if each muscle is contracted at the
same rate, then skeletal muscle would fatigue quicker because smooth muscle is a slow twitch
muscle, was proven to be correct. This can be shown based on the data collected in the lab
because when the skeletal muscle was contracted at the same rate as the smooth muscle, the
smooth muscle was at a constant rate and would never stop pulsing until one is dead, while the
skeletal muscle tired after 1000 contractions at the same rate. It can also be seen based on the
results that while looking at the 1 minute time period in which the skeletal muscle was contracted
as fast as possible, and the smooth muscle was still taken as beats per one minute, the skeletal
muscle was able to get more contractions in that one minute than the smooth muscle. Skeletal
muscle contracted at most 144/min while the smooth was only 66 BPM. However, with this
being said the skeletal muscle also tired much faster because of it working so hard, while the
smooth muscle did not tire at all, proving again that the skeletal muscle will always tire before
the smooth muscle. In the blood vessels, it is smooth muscle while in the hands and fingers there
is skeletal muscle. Skeletal muscle is composed mostly of fast fibers. Fast fibers have a rapid
breakdown of glucose for energy and because of this a buildup of lactic acid can occur and
fatigue occurs much faster. Slow fibers, however, which are contained in smooth muscle, are
fatigue resistant because the oxygen supply is greater due to more perfusion of blood vessels,
myoglobin proteins store oxygen in fibers, and oxygen use is efficient due to large numbers of
mitochondria. All of these help to explain why skeletal muscle tires faster than smooth muscle.
While the results that were gathered conclude the hypothesis was correct, there are a few
ways that the results could have been improved. First, the technique for squeezing the clothes pin
was not always the same. While beginning with only the thumb and pointer finger squeezing the
clothes pin, as the pin got harder to close it was a natural instinct the include the middle finger in
the squeezing process. By doing this, it would allow for more contractions of the skeletal muscle
and would make it appear as though the skeletal muscle did not tire as quickly. Another way to
improve the experiment would to be wait a set period of time during each trial. This would help
to improve the experiment because going straight from one trial to the next while the hand is
already tired would not provide accurate results. The skeletal muscle would most likely fatigue
even quicker because it would not have enough time to regain its strength, oxygen and glucose
levels.