Muscle fatigue is often accompanied by muscle pain. What is the most likely explanation for this pain?
A. the myofibrils being torn apart
B. decreased levels of glycogen in the muscle fibers
C. increased levels of Pi in the muscle fibers
D. decreased levels of ATP in the muscle fibers
E. decreased pH in the muscle fibers
Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
Gather Content
· What do you know about muscle fatigue? What other information is related to the question?
Choose Answer
· Given what you now know, what information is most likely to produce the correct answer?
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
E. decreased pH in the muscle fibers
Clarify Question
· What is the key concept addressed by the question?
o The question asks about muscle fatigue.
· What type of thinking is required?
o You are being asked to apply your knowledge about muscle fatigue.
Gather Content
· What do you know about muscle fatigue? What other information is related to the question?
o Muscle fatigue refers to the use-dependent decrease in the ability of a muscle to generate force. Fatigue is highly variable and can arise from a number of causes. The intensity of contraction as well as duration of contraction are involved. In addition, fatigue is affected by cellular metabolism: aerobic or anaerobic. In the case of short-duration maximal exertion, fatigue was long thought to be caused by a buildup of lactic acid from anaerobic metabolism. More recent data also implicate a buildup in inorganic phosphate (Pi ) from the breakdown of creatine phosphate, which also occurs during anaerobic metabolism. Anaerobic metabolism produces lactic acid as a by-product.
Choose Answer
· Given what you now know, what information is most likely to produce the correct answer?
o In fatigue, muscle cells do not receive enough oxygen to meet their needs and switch to anaerobic metabolism. A by-product of anaerobic metabolism is lactic acid production, which increases the H+ ion concentration and decreases the pH in the muscle fibers. This decrease in pH can cause a sensation of pain.
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
o This question asked you to apply your knowledge about muscle fatigue. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you think that low glycogen or ATP would produce pain? Did you think that muscle was being torn in fatigue, as opposed to just not having enough energy for the muscles to contract properly?
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