The human body consists of primarily two types of muscle fibers: type I and type II. Type II fibers have two subcategories: IIa and IIx. These fibers have different characteristics, capacities, and traits. Fast vs. Slow contractile speeds. Aerobic vs. anaerobic. High vs low mitochondrial density. etc. There are also color variations. 

With that said, the question "Can chickens fly?" may help us better remember the distinctions between the dark meat and relatively smaller muscles of the chicken legs and some other functions versus the white meat and much larger muscles of the chicken breast and how they relate back to type I and II muscle fibers in humans. 

Enjoy the listen.

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