Slow/Fast Twitch muscle fibers...

[SayWhuu]

What is the difference between slow and fast twitch muscle fibers?

[Trappy]

White are fast twitch glycolitic fibres, red are slow twitch oxidative fibres. Pink are intermediate oxidative type fibres. White are primarily used in sprinting etc, whereas red are used for endurance. Everyone has different amount which is why some people are naturall good at spinting or long distance, and why some people are okish at both. Pink can adapt to the type of training you do, so purely theoretical, lets say you have 40% white, 40% red and 20% pink, you have upto 20% room for either red or white.