Preferred walking speed

The preferred walking speed is the speed at which humans or animals choose to walk. Many people tend to walk at about . Individuals find slower or faster speeds uncomfortable. Horses have also demonstrated normal, narrow distributions of preferred walking speed within a given gait, which suggests that the process of speed selection may follow similar patterns across species. Preferred walking speed has important clinical applications as an indicator of mobility and independence. For example, elderly people or people suffering from osteoarthritis must walk more slowly. Improving (increasing) people's preferred walking speed is a significant clinical goal in these populations. People have suggested mechanical, energetic, physiological and psychological factors as contributors to speed selection. Probably, individuals face a trade-off between the numerous costs associated with different walking speeds, and select a speed which minimizes these costs. For example, they may trade off time to destination, which is minimized at fast walking speeds, and metabolic rate, muscle force or joint stress. These are minimized at slower walking speeds. Broadly, increasing value of time, motivation, or metabolic efficiency may cause people to walk more quickly. Conversely, aging, joint pain, instability, incline, metabolic rate and visual decline cause people to walk more slowly. Commonly, individuals place some value on their time. Economic theory therefore predicts that value-of-time is a key factor influencing preferred walking speed. Levine and Norenzayan (1999) measured preferred walking speeds of urban pedestrians in 31 countries and found that walking speed is positively correlated with the country's per capita GDP and purchasing power parity, as well as with a measure of individualism in the country's society. It is plausible that affluence correlates with actual value considerations for time spent walking, and this may explain why people in affluent countries tend to walk more quickly. This idea is broadly consistent with common intuition.