4. Discussion
impairment of the HRV, cardiovascular and metabolic diseases, hypertensive, cardiovascular or metabolic pathologies, hypertension
HBP, CARDIOVASCULAR DISEASES, METABOLIC DISEASES, EVENTS, HYPERTENSION, HIGH BLOOD PRESSURE
The interpretations of our results suggest that there was no difference in the autonomic modulation of HR between the elderly participants without cardiovascular and metabolic diseases (the control group), and the hypertensive group. However, there was a reduction in parasympathetic modulation between the pre-exercise moment (rest) and the five mins of recovery in the control group. Although we hypothesized that the autonomic modulation of heart rate in hypertensive participants would be lower than that of participants without cardiovascular or metabolic pathologies, our results show that the elderly in the control group had greater parasympathetic modulation (RMSSD, HF, and SD1) of HR 30 min post-exercise compared to the initial mins of recovery. Furthermore, there was no difference in the global variability of HR between participants without cardiovascular and metabolic diseases and those with hypertension. The aging process causes reductions in the parasympathetic activity of the heart, a fact that promotes a decrease in heart rate variability indices [In our study, elderly participants with hypertension and those without cardiovascular and metabolic diseases had similar global HR variability indices (SDNN, RRTri, TINN, and SD2), with no differences in parasympathetic modulation indices (RMSSD, HF, PNN50, and SD1). Distinct results were described by Andrade et al. [Perhaps the difference between the two study results may be explained by the intensity of physical activity by the elderly with hypertension in each study because physical training can normalize the sympathetic autonomic modulation and balance the sympathovagal system, which may positively affect the prognosis of cardiovascular diseases [Masroor et al. (2018) found that in sedentary hypertensive women, four weeks of combined aerobic training with exercises performed at 50–80% of the maximum heart rate, HR training similar to that in our study, was associated with an increase in HF and RMSSD, and a decrease in LF/HF, demonstrating improvement in cardiac autonomic control. Furthermore, combined aerobic and resistance training promoted significant improvement in HRV parameters, indicating vagal dominance in middle-aged hypertensive women [Within the context of physical activity, it is essential to verify not only the heart rate response at the beginning of exercise, which expresses the integrity of the vagus nerve, but also the recovery of HR in the post-exercise moments, because it provides important prognostic information. After all, individuals who have slow HR recovery in the initial mins post-exercise have a high risk of mortality [We found that during the initial 5 min of recovery (R1), the elderly without high blood pressure and metabolic diseases showed a decrease in parasympathetic modulation (HF and SD1) in relation to rest, but those parameters were restored to levels like those at rest only after 30 min post- exercise. In addition. we observed that the HF interacted between groups and moments (The control group had lower parameters associated with global variability in the five mins of recovery (SDNN, RRTri, and TINN), which remained small even after 30 min of recovery, compared to the rest moment. However, there was an increase in SD1/SD2 indices at 30 min post-exercise. On the other hand, the elderly without hypertension and metabolic diseases did not recover from the increase in sympathovagal balance, with LF/HF indexes higher than at rest, even 30 min after exercise, and had a decrease in cardiac autonomic modulation. Differences found during the post-exercise recovery period were described in a study that evaluated the impact of aerobic exercise on heart rate variability in male adults with a mean age of 20 years. The authors reported that heart rate gradually decreased during recovery without reaching pre-exercise values within 30 min post-training, they also found that there was a gradual increase in HRV and that the time and frequency domain indices continuously increased during recovery but remained at reduced values compared to supine rest for at least 30 min [Regarding the sympathovagal balance, elevation of the LF/HF index in individuals who do not have high blood pressure may be associated with increase in blood pressure during the performance of activities, with impairment of the HRV that indirectly reflect on the system autonomic nervous [The reduction in parasympathetic and autonomic modulation verified in the 5 min post-exercise in the control but not in the HBP group may be related to the specific characteristics of the elderly in the HBP group. The HBP group in our study consisted of physically active elderly who had controlled blood pressure. Thus, it is possible that the use of medication to control blood pressure associated with physical activity and adherence to non-pharmacological therapies contributed to the differences observed between the groups. Lifestyle changes such as a low-sodium diet [Furthermore, differences in heart rate recovery may vary in elderly hypertensive individuals depending on BP control. Amaro-Vicente et al. [Although hypertension causes a delay in heart rate recovery after maximal exercise tests, physical training can normalize HR during the post-exercise period in hypertensive patients. Physical training for a duration of four months can restore the post-exercise decline rate of the recovery heart rate in patients with HBP [Despite the benefits of aerobic exercise in improving cardiac autonomic control, clinical supervision is necessary, even for elderly people who do not have hypertension and cardiovascular diseases. Thus, knowing that there are risks of cardiovascular events during and after exercise, monitoring cardiac autonomic modulation by HR variability in periods after aerobic exercise can be an important tool for the elderly, regardless of the presence of cardiovascular and metabolic diseases, such as systemic arterial hypertension.Knowledge of risks of cardiovascular events during and after exercise and monitoring cardiac autonomic modulation by HR variability in periods after aerobic exercise can be an important tool for the elderly, regardless of the presence of cardiovascular and metabolic diseases, such as systemic arterial hypertension.