The influence of body size on measurements of overall cardiac function

The purpose of this study was to determine the best scaling method to account for the effects of body size on measurements of overall cardiac function and subsequently the interpretation of data based on cardiac power output (CPO). CPO was measured at rest (CPOrest) and at maximal exercise (CPOmax) on 88 and 103 healthy but untrained men and women, respectively, over the age range of 20–70 yr. Cardiac reserve (CR) was calculated as CPOmax − CPOrest. CPOrest, CPOmax, and CR were all significantly related to body mass (BM), body surface area (BSA), and lean body mass (LBM). The linear regression model failed to completely normalize these measurements. In contrast, the allometric model produced size-independent values of CPO. Furthermore, all the assumptions associated with the allometric model were achieved. For CPOrest, mean body size exponents were BM0.33, BSA0.60, and LBM0.47. For CPOmax, the exponents were BM0.41, BSA0.81, and LBM0.71. For CR, mean body size exponents were BM0.44, BSA0.87, and LBM0.79. ...