Motocross (also known as Moto X) is a form of motor cycle racing that originally took place on trails and off road venues. Motocross machines tend to be much lighter with a smaller engine displacement than conventional street motorcycles. The motocross machines are designed to be both maneuverable over rough terrain and constructed to absorb the significant forces created by the motorcycle's contact with the terrain.
Motocross races are organized according to classifications determined by the engine size of the machine. The first motocross races were held in England prior to 1930, in events known as "scrambles." The international motorcycle sports governing body, Federation Internationale Motocycliste (FIM), sanctioned the first ever motocross events in 1947. In the late 1960s, the first North American motocross events were held.
A typical outdoor motocross race course is between 1.0 and 1.5 mi (1.5 km to 2.5 km) in length. Most courses are built from a combination of natural terrain and man made alterations to the track to make it as demanding as desired by the organizer.
A modern variation of motocross is Super Cross, where the riders compete on a circuit artificially constructed inside a sports stadium. The Super Cross course is a series of irregular curves, artificial mounds and straightaways, with the riders seeking to complete a fixed number of laps in the shortest period of time.
Motocross has a similar interest in continuous technological improvement common to all sports where machinery places a key role. The largest of the motocross motorcycles have engines with a displacement of approximately 550 cc, supported by a structure that weighs less than 250 lb (115 kg). This combination of relatively powerful engine, light frame, and very strong suspension permit the machines to operate at high speeds.
Riding an FMX machine in competition is an extremely strenuous and physically demanding activity. The control of the motorcycle, both as it is operated at full speed as well as through jumps and turns requires muscular strength and stamina. The training to participate in FMX riding will include a considerable amount of aerobic fitness, as well as ensuring that the entire body subjected to stretching and flexibility training. The lumbar (low back) of the rider is particularly susceptible to strain due to the impact directed into that region through jump landings.