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Muscle Fiber Type IIx

Fast-Twitch Glycolytic

Anatomy

Short definition

Very fast glycolytic fibres — maximal force, fast fatigue.

Full definition

Type IIx (in humans; IIb in animals) are the fastest, strongest fibres with low mitochondrial density and fast fatigue, recruited at maximal and submaximal efforts (≥85 % 1RM, sprints).

Examples

A 60 m sprint uses IIx fibres.

Related terms

Muscle Fiber Type I Muscle Fiber Type IIa Strength Power