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Multiple Choice
Muscle fatigue is caused by ________.
A
the accumulation of lactic acid during anaerobic respiration
B
the direct use of fatty acids as the primary energy source
C
an increase in oxygen supply to muscle cells
D
the breakdown of glucose into carbon dioxide and water
Verified step by step guidance
1
Understand the concept of muscle fatigue: Muscle fatigue occurs when muscles lose their ability to contract effectively after prolonged activity. This is often linked to energy production and waste accumulation during cellular respiration.
Review the process of anaerobic respiration: During intense exercise, oxygen supply to muscle cells may become insufficient, leading to anaerobic respiration. This process generates energy but also produces lactic acid as a byproduct.
Analyze the role of lactic acid: Lactic acid accumulation in muscle cells can lower pH levels, interfere with enzyme activity, and contribute to the sensation of fatigue.
Evaluate the incorrect options: Fatty acids are not the primary energy source during intense exercise; glucose is. An increase in oxygen supply would reduce fatigue, not cause it. The breakdown of glucose into carbon dioxide and water occurs during aerobic respiration, which does not lead to lactic acid buildup.
Conclude that the correct answer is the accumulation of lactic acid during anaerobic respiration, as this directly explains the physiological cause of muscle fatigue.