Influência do nível de atividade física sobre a recuperação autonômica cardíaca após sessão aguda de exercício físico em diabético tipo 2

Abstract

Cardiac Autonomic Neuropathy (CAN) is a disorder in cardiac autonomic control, due to several pathological processes, among them Diabetes Mellitus is one of the most important due to its high prevalence. CAN promotes sympathovagal imbalance at rest, which can also be reflected during periods of post-exercise recovery. It can be evaluated by the analysis of the Heart Rate Variability (HRV), both at rest and in the post-exercise recovery, the latter being evaluated by specific methods for this period. Physical activity provides a change in the sympathetic and parasympathetic influences on the heart, necessitating the return of these autonomic influences on the heart to the rest equilibrium. The slowness in this recovery of the autonomic balance represents a great risk to cardiovascular health due to the high risk of cardiovascular events due to this state of autonomic imbalance. The main objective of this study was to evaluate the influence of the level of physical activity on autonomic recovery after physical effort in type 2 diabetic individuals. In this study 14 diabetic subjects of both sexes were divided into two groups: physically active (DMFA; n = 7; age: 57.57 ± 2.47 years) and insufficiently active (DMIA; n = 7; age: 54.29 ± 2.67). The HRV at rest analysis was performed through the electrocardiographic record, using both time and frequency methods. To evaluate the cardiac autonomic recovery, the volunteers performed a submaximal stress test, following the Bruce protocol. Time-varying methods and HRV-Time-frequency analysis were used, obtaining the RMSSD and HF indexes, from consecutive 30-second and 1-minute windows, respectively. For comparative analysis between groups, the t-test of Student or Mann-Whitney U test was used, according to the presence or absence of normality. For the analysis of the acute effect of exercise on HR during recovery, the One-Way ANOVA test was used and Pearson's correlation analysis was used to assess the association between physical activity level and cardiac vagal activity. The level of significance was 5%. The group of physically active diabetics had a lower resting HR, as well as increased cardiac vagal activity during rest and post-exercise recovery. The HR behavior during the recovery period was similar between the two groups, however, the group DMIA presented higher HR values when compared to their resting levels, even after 30 minutes of recovery. Regarding the analysis of the full vagal reactivation, we showed that only the DMFA group achieved complete full vagal reactivation. We conclude that the regular practice of physical activity is effective in promoting improvements in the autonomic behavior at rest, as well as in the autonomic recovery after exercise.