Skip to main content

Muscle Fiber Type Shifting

Meaning

The physiological adaptation process where skeletal muscle fibers transition their primary characteristics—specifically their metabolic and contractile properties—from one type to another, typically in response to a sustained change in training stimulus or hormonal environment. This “Shifting” primarily occurs between slow-twitch (Type I, oxidative) and fast-twitch (Type II, glycolytic) fibers, altering muscle endurance and power characteristics. This plasticity is a critical target for optimizing athletic performance and combating age-related muscle loss.