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.
â¢ A fast muscle like an eye muscle will have more fast-twitch motor units than slow ones â¢ A support muscle in the back will have more slow-twitch units â¢ A leg muscle that can be involved in both support and spurts of fast activity generally has a fairly equal mix of both.