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.
Rapid, synchronous muscle jerking: Introduction. Rapid, synchronous muscle jerking: also called myoclonus. They are quick, involuntary muscle jerks. See detailed information below for a list of 28 causes of Rapid, synchronous muscle jerking, Symptom Checker, including diseases and drug side effect causes. Â» Review Causes of Rapid, synchronous muscle jerking: Causes | Symptom Checker Â».