Scaling and adjusting growth-related data and sex-differences in the muscle-bone relation: a perspective.

ceptibility. However, the use of percentages of unscaled variables with differing geometric dimensions may lead to erroneous conclusions about the timing of bone growth in length, diameter and mass. Using small and large cuboids (with similar relationship [isometry] between length and width) as examples for a growing human long bone, it is evident that increments in one-dimensional length or width result in much greater increments in cross-sectional areas and even greater increments in volume and mass, simply as a mathematical necessity (see Figure 1). Therefore, it is not surprising that the weight (mass, kg) and height (cm) of a normally growing 8-year-old child correspond to ~30% and ~70% of the respective adult values. Any percentage comparison of variables with different dimensions therefore requires dimensional/geometric scaling.