What is the type of muscle that most resistant to fatigue?

The type of muscle that is most resistant to fatigue is the slow-twitch muscle fiber, also known as type I muscle fibers. These muscle fibers are characterized by their slow contraction and relaxation times, as well as their high oxidative capacity. This means that they are able to generate energy aerobically, using oxygen, for a sustained period of time. As a result, slow-twitch muscle fibers are primarily used for activities that require endurance, such as long-distance running or cycling.

Conversely, fast-twitch muscle fibers, or type II muscle fibers, are more powerful but fatigue more easily. These muscle fibers are characterized by their fast contraction and relaxation times, as well as their lower oxidative capacity. They are primarily used for activities that require power and speed, such as sprinting or weightlifting.

The relative proportion of slow-twitch and fast-twitch muscle fibers in a person's muscles is largely determined by genetics. However, training can influence the fiber composition of muscles, with endurance training increasing the proportion of slow-twitch fibers and power training increasing the proportion of fast-twitch fibers.