There is no such position as Mayor of the United States (US). A  Mayor is typically a political position for cities and towns. The  United States is led by a president. Curr â¦ ently, the president is  Barack Obama.
Fast-twitch muscles. Fast-twitch muscles use an 'anaerobic' metabolism to create fuel and need more oxygen, and they are much better at generating short bursts of strength or speed than slow muscles, such as a 100 metre sprint or weightlifting, but they tire more quickly.
Muscle fiber types can be broken down into two main types: slow twitch (Type I) muscle fibers and fast twitch (Type II) muscle fibers. Type I fibers are used in lower-intensity exercises such as very light resistance work aimed at muscular endurance and long-duration aerobic activities such as 5K and 10K runs.