Heart rate and ventilatory frequency as dimension-dependent variables.

Heart rate (HR) and ventilatory frequency (f) were determined at rest in 79 boys and 91 girls aged 0.07-20 years and with a range in heights from 54-198 cm to establish the relationship between decrease in HR and f during early life with increase in body dimensions. From theoretical considerations it is assumed that frequencies such as HR and f are proportional to a characteristic linear dimension of the subjects in minus first power (approximately equal to rho-1). In the present material resting HR and f decreased with increasing height of the subjects according to the equations HR = 6,408 . height-0.9015 (r = 0.8983) and f = 5,969 . height-1.1691 (r = 0.8471). These results suggest that the decrease in resting HR and f during childhood and adolescence corresponds well with increase in body dimensions. A similar equation was developed for HRmax within the range of heights from 149-198 cm. Only a slight dependency on height was observed (HRmax = rho-0.1642, r = 0.3796).