Comparación de un índice vagal a la misma frecuencia cardiaca entre los estados de ejercicio dinámico y de recuperación temprana

Abstract

Root mean square of successive differences (rMSSD) is an accurate index of the heart rate variability and it has been associated to autonomic vagal modulation. The aim of this study was to compare the behavior of this index in relation to the heart rate during the states of dynamic exercise and recovery. The heart rate and the rMSSD were obtained in ten subjects during three minutes of dynamic ramp exercise done in a climbing step, form rest to 80% of theoretical maximum heart rate, followed by four minutes of recovery. The rMSSD values were calculated using a ten second window around 55% to 75%, in 5% steps, of maximum heart rate for exercise and recovery. An analysis of variance for repeated measures was used to compare the rMSSD value between exercise and recovery and its values for the different heart rates, finding differences for both factors. The differences between the conditions were present for the heart rate values lower to 65% of the maximum heart rate. For relative heart rate above this value, the rMSSD did not change during exercise, probably due to vagal withdrawal. For recovery, the rMSSD increased noticeably below 65% of maximum heart rate, producing hysteresis.