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.
Slow twitch muscle fibres are good for endurance activities like long distance running or cycling. They can work for a long time without getting tired. Fast twitch muscles are good for rapid movements like jumping to catch a ball or sprinting for the bus.
The fast-twitch muscle fibers are those that have less endurance but have the most strength and power and grow the biggest. When you pick up a weight and do a biceps curl, the slow-twitch muscle fibers in the biceps are recruited first to contract and then lift the weight.