Contrast fast fibers with slow fibers in terms of diameter, glycogen reserves, myoglobin content, and relative abundance of mitochondria

The skeletal muscle fibres are of two types namely slow-twitch muscle fibres (type I muscle fibre) and fast-twitch muscle fibre (type II muscle fibre).

The slow fibres are slow contracting and help in developing endurance such as long distance running, maintaining posture etc whereas fast fibres are fast contracting and help in movements which require force such as sprinting etc.

Other differences are summarized in a tabular form attached below.