Change in heart rate variability threshold after short term aerobic training

Abstract

During incremental tests, there is a consistent reduction in heart rate variability (VFC) until approximately 3 ms value, when calculated through the Poincaré Plotting (STDB). A stabilization of this index is observed in the subsequent intensities. This transition point, called VFC threshold (LiVFC) by Lima and Kiss (1999), can be considered as an indicator of aerobic capacity, because of its high correlation with the lactate and ventilatory thresholds. The aim of this study was to verify the effects of three weeks duration aerobic training program on LiVFC. A 25 non-athlete sample was divided in a Training Group (TR, n = 18) and a Control Group (C, n = 7), submitted to a pre- and post-training incremental test until exhaustion, with an initial power output of 0 W and increments of 14.5 W per minute. The R-R intervals were recorded using a Polar equipment, S810i model, and the VFC was calculated by means of the Polar Precision Performance software. TR underwent nine training sessions (3 times a week) of 30 min duration, with the intensity of approximately 50% of the peak power output (PPico) and that one associated to the LiVFC (PLiVFC) interval. The comparisons were made by a two way repeated measures ANOVA, followed by the Scheffé test (p < 0.05). During the pre-training test there was no significant difference in the VFC responses between the groups. In the post-training measure, the VFC of the TR was greater until the power output of 145.75 W, which caused the increase in PLiVFC. The TR experienced no significant improvement in the PPico and in maximal FC. The submaximal FC of TR in the post-training was lower until the power output of 189.5 W. It was concluded that LiVFC presents sensibility to the short-term aerobic training effects, suggesting its validity as an indicator of aerobic capacity.