Levels of inactivity are high in virtually all developed and developing countries. In developed countries more than half of adults are insufficiently active. In rapidly growing large cities of the developing world, physical inactivity is an even greater problem. Urbanization has resulted in several environmental factors which may discourage participation in physical activity:

  population over-crowding

  increased poverty

  increased levels of crime

  high-density traffic

  low air quality

  lack of parks, sidewalks and sports / recreation facilities.

Consequently  diseases associated with physical inactivity are the greatest public health problem in most countries around the world. Effective public health measures are urgently needed to improve physical activity behaviors in all populations.