Which of the following indicators of muscular fatigue is most directly related to glycogen depletion?

• A. Decreased ability to sustain high-intensity exercise
• B. Elevated blood oxygen levels
• C. Increased production of lactic acid
• D. Accumulation of carbon dioxide in muscle tissue

Answer: (A)

Verified step by step guidance

1. Understand the concept of muscular fatigue: Muscular fatigue occurs when muscles lose their ability to generate force or sustain activity. This can be caused by various factors, including energy depletion, accumulation of metabolic byproducts, and reduced oxygen availability.
2. Review the role of glycogen in muscle activity: Glycogen is a stored form of glucose in muscles and serves as a primary energy source during high-intensity exercise. When glycogen stores are depleted, muscles struggle to sustain high-intensity activity.
3. Analyze the options provided: Elevated blood oxygen levels, increased production of lactic acid, and accumulation of carbon dioxide in muscle tissue are all related to metabolic processes during exercise but are not directly caused by glycogen depletion.
4. Connect glycogen depletion to decreased ability to sustain high-intensity exercise: Without sufficient glycogen, muscles cannot produce enough ATP (energy) to maintain high-intensity activity, leading to fatigue and reduced performance.
5. Conclude that the indicator most directly related to glycogen depletion is the decreased ability to sustain high-intensity exercise, as this is a direct consequence of the lack of energy available from glycogen stores.