A runner died of suffocation in one such pile up in 1977.
To minimize the impact of injuries every day 200 people collaborate in the medical attention.
Many runners that want to be seen wear colors other than white, a common alternate color choice is blue.
Others include large logos on their shirt to capture the attention of the bulls.
Though there is no formal dress code, the very common and traditional attire is white pants, white shirt with a red scarf around the waist and a red handkerchief around the neck.
Another common dress practice, seen as a risk by some but as a daring depiction of courage by others is dressing in a conspicuous manner.
The fence is composed of approximately three thousand separate pieces of wood.Some parts of the fence remain in place for the duration of the fiesta, while others are placed and removed each morning.The encierro begins with runners singing a benediction.Spanish tradition says the true origin of the run began in northeastern Spain during the early 14th century.While transporting cattle in order to sell them at the market, men would try to speed the process by hurrying their cattle using tactics of fear and excitement.