Allometric relationship between body size and peak VO2 relative to age at menarche

The present study examined allometric coefficients relating peak VO2 and bo dy size relative to the time of menarche. Peak oxygen uptake (peak VO2) dur ing exercise on a bicycle ergometer, stature and body mass were measured at annual intervals in a mixed-longitudinal sample of 40 active girls from 11 to 14 years of age. The girls were interviewed about their menarcheal stat us at each examination. The data were treated relative to the time before a nd after menarche: 2 years before (n = 18), 1 year before (n = 26), during the year of menarche (+/-6 months, n = 32), 1 year after (n = 35) and 2 yea rs after menarche (n = 22). Allometric coefficients were calculated fur eac h of the five menarcheal groups based on logarithmic transformations of pea k VO2 and body mass and peak VO2 and stature. The major axis of VO2 and bod y mass or stature (log transformed) was also calculated. This is the most a ppropriate slops for comparison with theoretical allometry coefficients. Me an peak VO2 increases from 2.1 +/- 0.19 L 2 years before menarche to 2.3 +/ - 0.25 L 2 years after menarche. The slope of the major axis for body mass is always higher (0.508-0.926) than that for the allometric coefficient (0. 323-0.591) in each of the menarcheal groups. The major axis slope and allom etric coefficient are lowest between body mass and peak VO2 during the year of menarche. The slope of the major axis is below the theoretical allometr ic coefficients assuming geometric or elastic similarity, 2/3 or 3/4, befor e and at menarche and increases after menarche. Although the differences ar e not statistically significant, the results suggest that the relationship between body mass and peak VO2 at menarche is lower compared with relations hips before and after this maturational landmark, Allometric coefficients f or stature relative to peak VO2 show a similar pattern.