Type 1 vs Type 2 Muscle Fibers Everyone is made up of a blend between type one and type two muscle fibers. Type one muscle fibers are the muscle fibers that are predominantly used for endurance type activities. Think about long distance runners, their body types are usually very slender, slim, and don’t carry much mass. But they could run very long distances for a sustained amount of time. Those types of bodies are predominantly type one muscle fiber dominant. Now, if you think about sprinters,