Is leg muscle mass decisive in reaching a plateau in oxygen uptake during maximal treadmill running? Analysis of data from the Amsterdam growth and health study.

Within the framework of a longitudinal study, the Amsterdam Growth and Health Study followed a group of males and females from their teens into early adulthood. Directly measured maximal oxygen uptake (VO max) was determined five times in 97 males and 103 females between 13 and 21 years of age during a constant speed (8 km/hr) and variable slope treadmill run to exhaustion. A change in oxygen uptake (VO ) of < 150 ml between the second last and final minute of the test was used as the criterion to determine the attainment of a plateau or leveling-off (LO) in VO . The purpose of this study was to investigate the relationship between VO max and the leveling-off criterion and other factors associated with the plateau phenomenon in this sample with increasing age. The VO max measurements over the years showed that 44-57% of males and 24-42% of females did not show a plateau. Moreover, subjects who did not reach leveling-off (no-LOs) showed slightly higher VO max values than subjects who reached the leveling-off criterion (LOs). These differences are significant (P < 0.05) in males from age 14.5 on, and in females only at age 21.5. Males who did not demonstrate a plateau in VO had a significantly higher total fat-free mass and lean leg volume (LLV) than males who demonstrated a plateau, but were not different in stature and weight. However, in females these differences were not significant. The apparent sex difference can be explained by the much smaller increase (25%) in LLV in females than in males. These results can be explained by the limitations of VO max by central and/or peripheral circulating factors. One possibility could be that during maximal uphill running, relatively less vasoconstriction occurs in the arterioles of larger exercising leg muscles, which permits an upward shift in VO and an increased demand on central oxygen transport mediated by increased peripheral metabolism. © 1994 Wiley-Liss, Inc.