White muscle fibres are characterised by the presence of high amount of 

White muscle fibres (fast-twitch fibers): These fibres typically have high sarcoplasmic reticulum, but a lower amount of myoglobin and mitochondria compared to red muscle fibers. They are adapted for quick, powerful contractions, relying more on anaerobic metabolism.

Red muscle fibers (slow-twitch fibers): These fibres generally have a higher amount of myoglobin and mitochondria. They are adapted for sustained, aerobic activities, relying on oxidative metabolism.