Muscle Action:
Muscles contract when in use and their length and circumference changes dependent on contraction or relaxation. For example, when you flex your bicep (bicep brachii), the circumference is greater and the muscle itself is shorter; the opposite occurs during relaxation.
http://www.arn.org/docs/glicksman/090104%20fig1biceps.jpg
Stressors affect the ability of muscles to properly function. One such stressor is coldness.
http://www.coolantarctica.com/gallery/scenic/Seaice%20formation/Antarctica_sea_ice_forming2.jpg
For this experiment, I made a certain number of fists in room temperature and shortly thereafter, a certain number number after submerging my hand in ice water for 60 seconds.
http://www.holidaycityflash.com/article%20pix/frostbite.jpg
Ok, maybe a bit dramatic for 60 seconds in ice water, although I almost felt ready for the Polar Bear Club!
Temperature | Number of Fists |
Normal | 45 |
Ice Water | 30 |
The cold definitely affected my ability to make a fist. The muscles were sluggish and tired, however, once the cold wore off toward the end, I felt like the fist were a little quicker. In the next experiment, I will test muscle strain under the stressor fatigue by squeezing a rubber ball a certain number of times within 20 seconds, 10 times.
| Trial | Number of Squeezes |
| 1 | 38 |
| 2 | 36 |
| 3 | 32 |
| 4 | 32 |
| 5 | 28 |
| 6 | 24 |
| 7 | 22 |
| 8 | 20 |
| 9 | 18 |
| 10 | 16 |
Over the course of the repetitions, my strength definitely diminished! Not to mention that is not a common, repetitive movement that is utilized day in and day out.
Conclusion:
Stressors such as cold and fatigue do affect muscles of the human body. Some of the process may be due to possible vasoconstriction and lack of blood flow from cold, along with the body beginning to focus on internal organs as opposed to the extremities. Fatigue possibly utilizes the supply of stored muscle energy at much higher rate with nothing left to replenish the depleted chemicals.
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