If a marathon runner experiences prolonged, intense exercise, which consequence concerning muscle function is most likely?

💡 Explanation

Intense exercise increases metabolic rate and reactive oxygen species production. Because antioxidant defenses become overwhelmed, increased oxidative stress then impairs muscle contractility by damaging proteins and lipids within muscle fibers. Therefore, contractility decreases, rather than enhanced protein synthesis or reduced fatigue, because oxidative damage dominates over adaptive responses.

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