Energy cost of treadmill and floor walking at self-selected paces.

Oxygen uptake-velocity regression equations were developed for floor and level treadmill walking by having two groups of men, aged 19-29 years (n = 20) and 55-66 years (n = 22), walk at four self-selected paces, from "rather slowly" to "as fast as possible". A two-variable quadratic model relating VO2 (ml X kg-1 X min-1) to velocity (m X s-1) was adopted for prediction purposes. However, age and fatness significantly (P less than 0.05) interacted with treadmill walking speed, while age alone significantly interacted with floor speed. In addition, a significant difference was found between the energy cost of floor and treadmill walking. For example at the normal walking speed of 1.33 m X s-1, the energy cost for the treadmill (age 55-66 years) was 10.58 ml X kg-1 X min-1 and for the floor, 11.04 ml X kg-1 X min-1 (P less than 0.05). Four quadratic equations are therefore presented, one each for floor and treadmill in each of the two age-groups. The percent variance explained was between 87 and 95% for each of these equations.