RESUMEN
The aim of this study was to evaluate constants of the Karvonen (k) and heart rate reserve (HRR) (α) formulas that correspond to the anaerobic threshold (AT) to conveniently estimate the intensity of exercise therapy in nonbeta-blocked patients undergoing hemodialysis. Twenty-three patients undergoing hemodialysis performed cardiopulmonary exercise testing (CPX) and their HR at AT was measured. The predictor coefficients for a target HR corresponding to AT were calculated for each patient based on CPX. Interclass correlation coefficients (ICC) and Bland-Altman analysis were used to evaluate the reliability of the formulas. Mean values of coefficient k of the Karvonen formula and α of the HRR formula were 0.24 ± 0.11 and 17.4 ± 8, respectively. The target HR calculated with k = 0.24 and α = 17 had significant ICC between HR at AT (0.74 and 0.77, respectively; P < 0.05). Using the Karvonen and HRR formulas to determine a target HR corresponding to AT is a simple and easy method that can be used to develop exercise programs for hemodialysis patients.