<P> There is an absolute limit on an individual's speed of walking (without special techniques such as those employed in speed walking) due to the upwards acceleration of the centre of mass during a stride--if it's greater than the acceleration due to gravity the person will become airborne as they vault over the leg on the ground . Typically however, animals switch to a run at a lower speed than this due to energy efficiencies . </P> <P> Many people enjoy walking as a recreation in the mainly urban modern world, and it is one of the best forms of exercise . For some, walking is a way to enjoy nature and the outdoors; and for others the physical, sporting and endurance aspect is more important . </P> <P> There are a variety of different kinds of walking, including bushwalking, racewalking, beach walking, hillwalking, volksmarching, Nordic walking, trekking and hiking . Some people prefer to walk indoors on a treadmill, or in a gym, and fitness walkers and others may use a pedometer to count their steps . Hiking is the usual word used in Canada, the United States and South Africa for long vigorous walks; similar walks are called tramps in New Zealand, or hill walking or just walking in Australia, the UK and the Irish Republic . Australians also bushwalk . In English - speaking parts of North America the term walking is used for short walks, especially in towns and cities . Snow shoeing is walking in snow; a slightly different gait is required compared with regular walking . </P> <P> In terms of tourism the possibilities range from guided walking tours in cities, to organized trekking holidays in the Himalayas . In the UK the term walking tour also refers to a multi-day walk or hike undertaken by a group or individual . Well - organized systems of trails exist in many other European counties, as well as Canada, United States, New Zealand, and Nepal . Systems of lengthy waymarked walking trails now stretch across Europe from Norway to Turkey, Portugal to Cyprus . Many also walk the traditional pilgrim routes, of which the most famous is El Camino de Santiago, The Way of St. James . </P>

A person who can not walk is called