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.
Your muscles operate in three basic movements: eccentric, concentric and isometric. Weight training and most cardiovascular exercises incorporate both eccentric and concentric motions. Concentric motions occur when your muscles are shortened and eccentric motions involve the lengthening of your muscles.