Prediction of maximal heart rate (HRmax) in healthy children and adolescent boys

Background and Aim: Measuring or estimating maximal heart rate (HRmax) as a physiological indicator is of great importance in adjusting the intensity of exercise training and rehabilitation programs. However, due to the implementation problems of the standard HRmax measurement, sports science experts recommend HRmax estimation equations. Most of these linear/nonlinear regression prediction equations are designed using samples of adult populations (20 to 90 years old), which seems to limit the application of such estimation equations to child and adolescent populations in different geographical regions due to the intervening role of the biological maturation process. Therefore, the purpose of this research is to design a native equation for estimating the HRmax for healthy Iranian children and adolescent boys.
Material and Methods: In the present study, the HRmax was measured in a modified Bruce's test on a treadmill equipped with a respiratory gas analysis device in 349 healthy boys aged 8 to 17 years in Hamedan city. Also, anthropometric and physiological variables of the subjects were measured in resting conditions using standard methods. Pearson's correlation was used in order to investigate the relationship between independent variables and the measured HRmax. Stepwise regression was used to design the native equation for HRmax estimation. The indexes of coefficient of determination (R2), standard error of estimate (SEE), percentage of standard error of estimate (SEE%) and normal distribution of errors were used to evaluate the efficiency of the native model.
Results: The average ergometric HRmax of the subjects was 202.44±6.12 beats per minute. There was a weak and significant correlation between HRmax and the independent variables of age, height and weight (R=-0.131-0.198) (p<0.05). The HRmax of children and adolescent boys could be estimated according to the native equation "maximal heart rate (bpm) = 208.015 - 0.452 × age (years)" (p=0.0002). However, the indicators of the native equation do not have high power. So that the coefficient of determination of the equation was equal to (R2=0.04) and the standard error index was (SEE=6.14 bpm), which was equivalent to 3% of the average measured HRmax.
Conclusions: Considering the low power of the statistical indicators in the native equation of the present study, the use of the number 202 as the upper limit of maximal heart rate for Iranian children and adolescents’ boys is recommended to control the intensity of training in sports and rehabilitation programs. Evaluating the results obtained in the present study for greater confidence and generalization to the child and adolescent community will be very valuable.