TWITCHY MUSCLES

Athletes hope for it and train for it. It’s that sudden burst of energy at a critical moment when they can sprint ahead in a competition. At the muscular level, such energy bursts come from fast-twitch muscle fibers. They make and release small amounts of energy quickly, without using oxygen. Fast-twitch muscles fire their energy during rapid movements, such as sprints, fast breaks, and the quick moves we make in daily life. Blinking is one of those fast moves, so eye muscles are made up of fast-twitch fibers. Slow-twitch muscle fibers, on the
other hand, are our everyday workhorses. They make energy slowly and steadily from oxygen. Because oxygen fuels the energy they make, slow-twitch muscles contain many more blood vessels than fast-twitch fibers. Slow-twitch muscles are active during long-distance walking, running, swimming, and other physical

activities that require a constant, steady supply of energy. They do not tire as quickly as fast-twitch muscle fibers do. Many experts believe that people inherit the number of slow-twitch and fasttwitch muscles they have. If that is true, then that means certain individuals are better suited to certain sports that involve more fast-twitch muscle fibers, such as sprinting. However, some scientific studies that show an individual who trains intensively in sports requiring fast motion can develop more fast-twitch muscles.