AI Summary

Muscle strength declines with age because the mitochondria that power muscle fibers become less efficient. Human muscles contain fast‑twitch fibers that generate quick, powerful bursts but fatigue rapidly, and slow‑twitch fibers that support endurance and contain more mitochondria. Aging reduces overall muscle mass and impairs mitochondrial function within both fiber types. The result is weaker, less resilient muscle tissue in older adults.

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