Which fibre type is best suited to short explosive bursts?

• A. Type 1
• B. Type 2x
• C. Type 2a
• D. Type 2b

Answer: (D)

For very short, powerful efforts you need muscles that can generate a lot of force quickly and then fatigue quickly. The fastest, most powerful fibres are the fast glycolytic ones. They have high myosin ATPase activity, contract rapidly, and rely mainly on anaerobic processes to provide energy, which allows them to produce peak power in a matter of seconds before fatigue sets in. That makes Type 2b fibres the best match for brief explosive bursts like sprint starts or vertical jumps. In contrast, slow-twitch Type 1 fibres contract slowly and resist fatigue but can't produce high force quickly, and Type 2a fibres are fast and more fatigue-resistant than 2b but don't reach the same explosive power.