Secular trend in peak oxygen consumption among United States youth in the 20th century

The purpose of this study was to examine secular change in peak oxygen consumption (Vo(2)) in U.S. boys and girls using available data from the 20th century. Studies were primarily identified from review articles and a Medline search. To be included in the analysis, studies must have included direct measurement of peak Vo(2) on healthy (free from overt disease) United States children and youth from the general population separated by sex. Data (mean values) were divided by decade and separated into three age groups: 6-12, 13-15, and 16-18 years for boys, and 6-11, 12-14, and 15-18 years for girls. Peak Vo(2) values were expressed as related to bipedal locomotion; therefore, cycle ergometry values were corrected by a factor of 1.075. Mean values were fit by least squares, goodness-of-fit regression lines. Results indicate that absolute (L x min(-1)) and relative (ml x kg(-1) x min(-1)) peak Vo(2) have remained relatively stable among boys and young girls. In adolescent girls, particularly those 15 years of age and older, peak Vo(2) has decreased by approximately 20% over the past few decades. The available data indicate that aerobic fitness has not decreased in United States youth except in adolescent girls over the past few decades.