What kind of muscles do distance runners have?

Slow-twitch muscles: Distance runners rely heavily on slow-twitch muscles, which are also known as type I muscles. These muscles are characterized by their ability to generate force over a long period of time, making them ideal for endurance activities like running. Slow-twitch muscles are also more resistant to fatigue than fast-twitch muscles, allowing distance runners to maintain a steady pace for longer periods of time.

Fast-twitch muscles: While distance runners primarily use slow-twitch muscles, they also have some fast-twitch muscles, which are also known as type II muscles. These muscles are capable of generating more force than slow-twitch muscles, but they fatigue more quickly. Fast-twitch muscles are important for distance runners in certain situations, such as when sprinting or accelerating.

Mixed-fiber muscles: In addition to slow-twitch and fast-twitch muscles, distance runners also have some mixed-fiber muscles, which contain a combination of both slow-twitch and fast-twitch fibers. These muscles are versatile and can be used for a variety of activities, including distance running.

The proportion of slow-twitch to fast-twitch muscles in a distance runner's body can vary depending on their training and genetics. Some runners may have a higher percentage of slow-twitch muscles, which can give them an advantage in endurance events, while others may have a higher percentage of fast-twitch muscles, which can make them better suited for shorter, more explosive events.