Unit Three, Muscle Lab

This lab was a muscle testing. We began by observing our bicep at rest, and then observing changes as it was extended. Next, we repeatedly made a fist with one hand over a period of twenty seconds. Then we introduced ice to the testing to see how change in temperature would effect muscle activity. Following this we introduced a rubber ball--to be held while making the fist. (I chose to use a round pencil sharpener, as that was what I had available). Lastly, we did nine repetitions of the initial exercise (tightening one hand into a fist). This was to gage whether fatigue would have an impact on muscle activity.







These two pictures were taken during the lab. The image on the left shows myself about to make a fist around the pencil sharpener. The image to the right is preparation for the change in temperature testing.


Effect of Temperature on Muscle Action:

Number of fists in 20 seconds
normal temp. = 21 fists
after ice = 17 (very uncomfortable!) fists

Number of fists in 20 seconds *with pencil sharpener
normal temp= 15 fists
after ice = 12 fists

Number of fists per trial
1. 16
2. 16
3. 15
4. 15
5. 15
6. 16
7. 13
8. 12
9. 13
10.13

Analysis of Data:
1. What are the three changes you observed in a muscle while it is working (contracted)? When an activity is repeated the muscle is tired and can not perform the activity at its initial rate of speed. The muscle is tight/hardened when it it working. Also, the muscle appears larger when it is flexed.

2. What effect did the cold temperature have on the action of your hand muscles? Explain. The cold was very uncomfortable for my hand muscles--I had a hard time even keeping them in the ice. The change in temperature made it more difficult to open and close my hand. It was very constricting to the muscle.

3. (graph eliminated)

4.What effect did fatigue have on the action of your hand muscles? Explain. Fatigue slowed the action of the hand muscles. As I progressed through the trials, the longer I had been doing the activity, the lower the number of fists I was able to make.



It seem the contraction of the hand muscle was an attempt to warm the hand. The muscles were contracted in order to break down ATP to regulate the sudden change in temperature. Also, due to the nature of the exercise, the muscle did not have time to relax between fists for the final testing. Calcium was not returned to the muscle and therefore the hand muscles wanted to remain contracted and the action of making a fist was slowed down.