[English translation] Maximum heart rate prediction equations fail key external validation test

Maximum heart rate equations (HRmax) have been used due to their easy availability and practicality, as compared to stress tests. However, the best-known equation, “220 – age”, shows low reliability and deviations of up to 12 beats/min. New formulae have been proposed, but they have not been correctly validated. The purpose of this study was to validate 7 prediction equations by using an independent data set. A data base of 634 subjects (474 men and 160 women) 18–85 years of age, obtained within a health service developed at the University of Michigan from 1990–1992, has been used. The subjects performed a VO2max test on a treadmill, following a free protocol. A linear regression technique was used in which the appropriate equations were those that met the two hypotheses: slope = 1 and constant = 0. According to the results, none of the equations analyzed for the full sample accepted both hypotheses. When doing the analysis by sex, six of the equations met the two hypotheses for the women, but none of them for the men; and when the analysis was done by age group, 4 of the equations met the hypotheses for the group 40 years old or younger, but not for those above 40. The HRmax seems to be difficult to predict through a single equation. Therefore, it is recommended that, when a valid measure for this variable is needed, a stress test be used.