Running economy: changes with age during childhood and adolescence.

The purpose of this study was to synthesize work directed at describing and understanding changes in running economy (the steady-state demand for oxygen at a set running speed) that occur with increased age during childhood and adolescence. Although the data are limited, a number of tentative conclusions were drawn. Children are less economical than adults. Running economy improves steadily with age in normally active children and adolescents, even in the absence of formal running training. Running economy in later childhood fails to respond to either short-term instruction on the techniques of running or short-term participation in running training. Long-term participation in running training may augment improvements in running economy that occur naturally with age. In a group of heterogeneous subjects of the same age, running economy is not strongly related to performance. Within a subject over a period of years, running economy is strongly related to performance. Children are less economical than adults because when compared with adults, children exhibit (a) higher resting metabolic rates, (b) greater ventilatory equivalents for oxygen, and (c) disadvantageous stride rates and stride lengths.