Fast-twitch muscles: Twitch and you're gone - all you need to know about developing fast-twitch muscle fibre for speed, power and strength

There are more than 250 million muscle fibres in our bodies and more than 430 muscles that we can control voluntarily. There are two basic types of fast-twitch fibre: Type IIa, aka ‘intermediate’ fast-twitch fibres or ‘fast oxidative glycotic’ (FOG) fibres because of their ability to display, when exposed to the relevant training stimuli, a relatively high capacity to contract under conditions of aerobic or anaerobic energy production; Type IIb fibres, the ‘turbo-chargers’ in our muscles, which swing into action for a highperformance boost when needed. Fast-twitch fibres are thicker than slow ones and it is the former that grow in size (hypertrophy) when activated by the ‘right’ training. Activating fast-twitch motor units is the key to improved strength, speed and power.