If a marathon runner experiences localized muscle fatigue primarily in their quadriceps late in a race, which consequence follows from the buildup of metabolic byproducts in these muscles?

💡 Explanation

Muscle fatigue slows cross-bridge cycling because anaerobic metabolism leads to lactate and hydrogen ion accumulation, decreasing pH and interfering with calcium binding to troponin, therefore reducing the number of active cross-bridges, rather than enhancing oxygen binding or ATP production.

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