"Type IIx<span> are best known as </span>fast-twitch<span> muscle fibers. These are the muscle fibers primarily responsible for fast, </span>explosive<span> movements like sprinting. However, they lack the endurance-boosting ability of </span>slow-twitch fibers<span> and can only be used for </span>short periods of time" <span>running.competitor.com/2014/07/training/the-role-of-muscle-fibers-in-running_82416
Type IIx<span> are best known as </span>fast-twitch muscle<span> fibers. These are the muscle fibers primarily responsible for fast, </span>explosive<span> movements like sprinting. However, they lack the endurance-boosting ability of </span>slow-twitch fibers<span> and can only be used for </span>short<span> periods of time</span>
