Children usually start to walk at about one year of age. During their growth from that age to adulthood, their weight will increase about 6 to 9-times and their height will increase about 2 to 2.6-times. Although the effect of the change in body shape and mass on the mechanics of walking has been studied in children, little data exist on the effect of growth on the energy cost of walking. Furthermore, to the best of our knowledge, no previous study measured the standing energy consumption of the subjects, making calculations of the net cost of locomotion much less secure.

In this study we determine for the first time the standing energy cost and energy cost of walking in children from 3 to 12 years of age and in young adults. The oxygen consumption and carbon dioxide production were measured while standing and walking at different speeds from 0.5 m s^-1 to near their maximum aerobic walking speed.

Standing oxygen consumption decreases with age: on the average from 3.5 W kg^-1 in the 3-4 year-olds to 2 W kg^-1 in young adults.

At all ages the gross cost of transport shows a minimum which decreases on the average from 6 J kg^-1 m^-1 in 3-4 year-olds to 3.5 J kg^-1 m^-1 after 10 years of age. The speed at which this minimum occurs increases from 1.2 m s^-1 to 1.5 m s^-1 over the same age range.

At low and intermediate walking speeds the net cost of transport is similar  in children and adults (about 2 J kg^-1 m^-1). In young children walking at their highest speeds the net cost of transport is 70% (3-4 year-olds) to 40% (5-6 year-olds) greater than in adults.

The differences observed between children and adults for the most part disappear when the speed is normalized (Fig. here under) based on the assumption that the subjects move in a dynamically similar manner (i.e. all lengths, times and forces scale by the same factors). This indicates that people of all ages walk in a dynamically similar way. This finding indicate that after the age of 3-4 years the differences in cost of transport may be explained mostly on the basis of body size alone, and that developmental changes in the neuromuscular system play a relatively minor role.

More information: Dominique Dejaeger

Main publication of lab on that topic : DE JAEGER D., WILLEMS P.A. & HEGLUND N.C. (2001) The energy cost of walking in children. Pflugers Arch. 441: 538-543

Return to the main page

Responsable : Philippe Gérard - Contact : pHg