Twitch or muscle twitch is a term used for muscle contraction.
Most muscles are made up of two kinds of muscle fibres that help you move your body:
- Slow-twitch muscle fibres move more slowly but help to keep you moving longer
- Fast-twitch muscle fibres, which help you move faster, but for shorter periods
Slow-twitch muscle fibres use an aerobic energy system. Fast-twitch muscle fibres don’t need as much blood because they make their own quick source of energy.