Unit 3, Lab 2

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This lab is to test the effects of muscle fatigue and how the cold effects the function of muscles. First, i recorded how many times i can make a fist in 20 seconds. Then i submersed my hand in a ice/water mix for 60 seconds. I then recorded how many "fists" i could make in 20 seconds.

NORMAL Temp. # of fists: 45

Ice Water # of fists: 40

Next, I wanted to know the effect of fatigue on muscle action while squeezing a rubber ball. I did this for 20 seconds, with 10 trials. I did not rest between each trial.

1. 50

2. 47

3. 40

4. 35

5. 28

6. 21

7. 19

8. 15

9. 8

10. 3

1. What are the three changes you observed in a muscle while it is working (contracted)? I noticed that the muscle would enlarge, it would also tighten up, and i could not continue with the same rate due to muscle fatigue

2. What effect did the cold temperature have on the action of your hand muscles? Explain. The cold caused my muscles to constrict due to the vasoconstriction secondary to the cold water. This in turn, made my muscle feel stiff. I had a hard time making my fist due to the initial vasoconstriction, and the end result made it hard for me to "catch up" with the demand.

3. What effect did fatigue have on the action of your hand muscles? Explain In the beginning, my body was able to keep up with aerobic demand of my muscles. However, this was a task specific challenge placed on group of muscles. As i continued with the exercise, my muscles had received adequate O2, but because i did not rest between trials,i think it is possible that the O2 demand for that specific group of muscles was greater than available. The end result was anaerobic cellular respiration with possible hypertrophy of those muscles.