Changes

The chart<ref name="selective"/> below shows that muscles do not become glycogen depleted at the same time. At all intensities shown, slow twitch fibers become depleted before fast twitch. The depletion within a fiber type is also not equivalent, with some fibers becoming depleted while others are fully loaded. This pattern implies a pattern of fiber recruitment[[Muscle Recruitment]], where a subset of muscle fibers are recruited until they become exhausted, at which point other fibers are then used. As the slow twitch fibers become exhausted, fast twitch fibers are used in turn.