Recovery of Heart Rate Variability After Exercise Under Hot Conditions: The Effect of Relative Humidity

Abstract

Introduction-The aim of this study was to analyze changes in heart rate variability (HRV) during exercise in hot environments and recovery to baseline values depending on relative humidity. Methods-Ten recreational runners participated in this study. Each participant performed 2 trials consisting of 30 min of continuous running under hot and dry (HD) (38˚C and 28% relative humidity) and hot and humid (HH) conditions (38˚C and 64% relative humidity) at their common 10 km race-running rhythm. HRV and body mass were assessed pre-and post-trial; the rating of perceived exertion and HRV were assessed during the trial; and HRV measurements were repeated 2, 4, 8, and 24 h postexercise. Primary HRV outcomes were root mean square of the successive differences, high frequency power, stress score, and sympathetic/parasympathetic ratio. One-way analysis of variance testing was used to analyze differences. Results-No significant difference in body mass occurred across the different conditions or distances covered (P>0.05). Rating of perceived exertion presented the highest correlation values with stress score (r=0.729 for HD; r=0.568 for HH) and sympathetic/parasympathetic ratio (r=0.621 for HD; r=0.519 for HH) during exercise. HRV recovered to baseline values more quickly after exercising under dry conditions (4 h) than under humid conditions (between 8 and 24 h). Conclusions-Stress score and sympathetic/parasympathetic ratio seem to be the best HRV predictors of internal load. Although there are no differences in HRV during recovery at the same time points in both conditions, the recovery is slower after exercise in HH than in HD.

Baroreflex Modulation During Acute High-Altitude Exposure in Rats

“…Other potential limitation of our study, was the different relative air humidity during the two experimental conditions. Nevertheless, it is important to mention that the experiments were carried out in typical environmental condition to which it is subjected when a person is exposed to High-Altitude (Bruce-Low et al, 2006;Abellán-Aynés et al, 2019). Finally, we did not use pharmacological approaches to characterize sympathetic and parasympathetic contributions to cardiac BR control after high-altitude exposure.…”

Comportamiento de las colinesterasas tras condiciones de fatiga en corredores de fondo

“…El LnRMSSD, como era de esperar, desciende después del ejercicio y el SS aumenta inmediatamente en la toma FINAL respecto a la toma BASAL, por la suspensión casi total de la actividad parasimpática y elevación simpática, tal como lo han reportado varios estudios [31][32][33][34]. Se ha descrito dentro de la literatura que esto se pudiera deber a que cuanto mayor es la intensidad relativa del ejercicio, mayor es la carga metabólica (H + , fosfato inorgánico, liberación de epinefrina), que tendrá un efecto sobre la estimulación barorrefleja y metabolorrefleja que estaría relacionado con una baja actividad parasimpática y una alta actividad simpática [10,[35][36][37].…”

A Study of Influence of Mental and Physical Load on the Indicators of Heart Rate Variability in Students With Different Dominant Types of Autonomic Regulation

“…In particular, heart rate variability (HRV) has become a useful tool for analyzing the cardiovascular system in both research and clinical fields [14]. The assessment of stress and the sympathetic/parasympathetic balance is the best prognostic indicator of HRV regarding internal load [15].…”