Trappe says regular folks have 1% to 2% superfast-twitch skeletal muscle mass, but in a sprinter like Bolt, that figure may be up to 25%.

• 特拉佩说一般人在骨架肌肉群中有1%25到2%25的超快缩肌肉，但是像博尔特这样的短跑运动员，这个比例将达到25%25。