Formulas are presented which establish a meaningful interrelationship between blood pressure and heart rate during exericse, describing both of them as functions of one variable and a set of common parameters, namely, a quantity interpreted as a no-load effort, and the rest values of heart rate and of systolic and diastolic blood pressure. The formulas can be used, in the place of graphic representations, to define the ranges of normal blood pressure and heart rate quite generally, or for specific populations. They can also be used to define the degree of hypertension of individuals or groups of individuals. The specific formulas and the ranges of normal values presented here, apply to men aged 20–50 years; they may have to be modified for other age groups.