ABSTRACT
Physical activity can be hazardous as well as beneficial to health. Jogging, walking and cycling inevitably increase exposure to the risk of injury through collisions with vehicles and falls due to uneven surfaces in pavements. Cycling is particularly hazardous. Around 500,000 injuries per year incurred during this activity are treated in US departments of emergency medicine and 800 people die; about one-third of injuries are to the head and these account for three quarters of deaths among cyclists. In the UK, 158 cyclists were killed on the roads in 1999 which was 5% of all fatalities.
