For this lab, I will be observing how fatigue comes upon a muscle over a given amount of time during a strenuous activity. To observe these effects, we will compare the muscle under different conditions. One condition would be putting the muscle subject to cold temperatures and comparing those results to that same muscle's action during room temperature conditions. Next, I will do repetitions to see the effect on that same muscle. Will fatigue set in? If so and if not, why?
Here are the activities I performed to observe muscle action:
1. Place your fingers along the angle of your jaw just in front of your
ear. Grit your teeth and observe what happens to the hardness of the
muscles in your cheek.
2. With the thumb and little finger of one hand, span the opposite arm's
biceps (front muscle of the upper arm) from the elbow to as close to the
shoulder as possible. Bend the arm and observe the change in the length of
the muscle.
3. Wrap a strip of paper around your upper arm and mark the circumference
of your arm on the paper. Clench your fist tightly and mark the new
circumference on the paper. Observe what happens to the circumference of
the muscle.
Effect of Temperature on Muscle Action
1. Count the number of times you can make a fist in 20 seconds. Start with
Your hands completely outstretched and make a tight fist each time. Do it
as rapidly as you can.
2. Now submerge your hand in a dishpan of water to which has been added
snow or ice so that the temperature is near the freezing point. Leave your
hand in the water for one full minute.
3. Remove your hand and immediately count how many forceful fists you can
make in 20 seconds.
Effect of Fatigue on Muscle Action
1. Count how many times you can tightly squeeze a rubber ball in your hand
in 20 seconds.
2. Repeat the squeezing nine more times and record results. Do not rest
between trials.
(An alternative procedure which works well is to open and close a
clothespin with the thumb and index finger while the other fingers are held
out straight.)
Materials Used
Large bowl
A doll *instead of a ball*
PLenty of ice
Water (that had been in the freezer a long time--almost frozen)
Clock
Measuring Tape
***From doing the activities for the muscle action, placing my fingers close to my ear on the jaw bone allowed me to observe that by gritting my teeth the muscle there contracts. This tightening, contraction, also describes how it gets smaller in length. The calcium in my jaw's skeletal muscle causes the contraction due to the body's central nervous system's response. Same goes for the next activity--placing my fingers along my bicep on my opposite arm. Again my muscle seems to be contracting. The same stiffness and shortening length seems to be occurring. When I gritted my teeth, I did not have a "bulge" in my mouth, rather just a stiff looking face. When I flexed my bicep, however, it got noticeably bigger. For the last muscle action activity (in the first section), I took a tape measure to my upper arm and measured the distance all the way around it. Then I made a strong fist and measured again. The contraction measurement wasn't nearly as big as that of my bicep, this was about a half an inch bigger.
***Now, it is time to see how temperature affects muscles. My hand has been subjected to room temperature (about 72 degrees Fahrenheit). I will submerse my hand into ice cold water (at the freezing point) for one minute. Here are my results:
1. Count the number of times you can make a fist in 20 seconds. Start with
Your hands completely outstretched and make a tight fist each time. Do it
as rapidly as you can.
***I was able to make a tight fist 32 times at room temperature.
2. Now submerge your hand in a dishpan of water to which has been added
snow or ice so that the temperature is near the freezing point. Leave your
hand in the water for one full minute.
***This was freezing. My hand started to burn a little but then it subsided.
3. Remove your hand and immediately count how many forceful fists you can
make in 20 seconds.
***I was able to make a tight fist only 22 times (same hand) after having it in freezing water for a full minute.
***For the last section of the lab, I squeezed a doll in my hand for 20 seconds. I am still using the same hand that went from room temperature to freezing it for an entire minute. I will squeeze the doll for 20 seconds and once I record the amount of squeezes I get, I will repeat it. I will repeat this step a total of 10 times (shown below). I believe from my data, it is clear that fatigue did set in. I went from 32 repetitions in normal room temperature to 22 repetitions in freezing water to 29 and down to 13 with 10 repetitions with a doll.
1st set: 29
2nd set: 28
3rd set: 24
4th set: 22
5th set: 19
6th set: 21
7th set: 19
8th set: 16
9th set: 14
10th set: 13
*Analysis of Data
What are the three changes you observed in a muscle while it is working (contracted)?
***I noticed a reduction in the length, an increase in touch (harder), and it was also larger in measurements around it.
What effect did the cold temperature have on the action of your hand muscles?
***The colder temperature restricted the muscles, making them react slower. The calcium's ability to flow was slowed. The myosin and actin proteins were also slowed down.
Conclusion:
***Calcium, actin, and myosin are all affected at the cellular level during due to temperature differences and fatigue. The cold water would have slowed any metabolic functions, thus slowing the entire process. It is not shocking to see that the number of fists declined with the addition to such cold water. Without calcium, actin, and myosin, the muscle's cells cannot function properly. The contraction dissipates. A fatigued muscle needs time to fuel up on oxygen and blood. This helps the muscles move alongside one another and contract in the way they are needed.
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