Many medical studies have shown links between physical exercise and health, and established the physiological and psychological mechanisms explaining these links. People who exercise regularly, about 30 minutes a day and about three times a week, are fitter and less liable to illness, and can perform everyday tasks with less stress and fatigue. However, the fitness of the population in the UK, USA, and other affluent nations is decreasing, because most people are taking insufficient exercise. Cycling and walking are realistic ways in which almost all people can keep fit. They can be used as a travel mode by most people from childhood to old age, and can often be linked to daily travel patterns to school, work, and leisure and other destinations. However, only 3% of the distance travelled in the UK is by walking and only 1% by bicycle. isincentives to walking include: danger from increasing road traffic, poor and unpleasant pavements, and, in many urban areas, fears of assault. Most of these problems could be solved by investing relatively small sums of money. The main deterrent to cycling is public perception of road accident risks, but the fatality rate from accidents to cyclists could be greatly reduced by cycle tracks, and seems to be less than that from heart attacks due to lack of exercise.
Abstract