Normalization of maximal cardiovascular variables for body size in premenarcheal girls

Previous studies have indicated the importance of allometric scaling of VO2max for body size. However, no information is available on adjusting maximal cardiac output (Qmax) and stroke volume (SVmax) for body dimensions. The allometric exponent b was determined for the equation Y = aXb (where Y is the physiological outcome and X is the anthropometric variable) for VO2max, Qmax, and SVmax 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 Qmax and SVmax, approximating that of 1.0 using the traditional ratio standard (cardiac index and stroke index). Exponents of body mass relative to VO2max, Qmax, and SVmax (0.55, 0.55, and 0.59, respectively) eliminated the effects of body size, but the ratio standard (M1.0) 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.