Normalization of Maximal Cardiovascular Variables for Body Size in Premenarcheal Girls

Abstract.

Previous studies have indicated the importance of allometric scaling of VO_2max for body size. However, no information is available on adjusting maximal cardiac output (Q _max) and stroke volume (SV_max) for body dimensions. The allometric exponent b was determined for the equation Y=aX ^b (where Y is the physiological outcome and X is the anthropometric variable) for VO_2max, Q _max, and SV_max relative to mass, height, and body surface area (BSA) in 24 premenarcheal girls (mean age 12.2 years) during cycle testing. Values for b were 1.08 and 1.05 for BSA relative to Q _max and SV_max, approximating that of 1.0 using the traditional ratio standard (cardiac index and stroke index). Exponents of body mass relative to VO_2max, Q _max, and SV_max (0.55, 0.55, and 0.59, respectively) eliminated the effects of body size, but the ratio standard (M ^1.0) did not. In this group of subjects, use of the ratio standard BSA was an appropriate means of adjusting maximal values of Q and SV for body size.