Physical Exercise and Non-Pharmacological Intervention in Autonomic Modulation and Control of Cardiovascular Diseases
Autonomic nervous system (ANS) plays an important role in the regulation of the physiological processes of the human organism during normal and pathological conditions. Among the techniques used in its evaluation, the heart rate variability (HRV) has arising as a simple and non-invasive measure of the autonomic impulses, representing one of the most promising quantitative markers of the autonomic balance. The HRV describes the oscillations in the interval between consecutive heart beats (RR interval), as well as the oscillations between consecutive instantaneous heart rates. These parameters have proved to be good predictors of morbidity and mortality in the clinical sphere, despite the need for scientific deepening, with expressive samples and prolonged follow up. Such studies may be useful in research and treatment of heart disease. Currently, the HRV indexes have been used to understand various conditions, such as coronary artery disease, cardiomyopathy, arterial hypertension, myocardial infarction, sudden death, chronic obstructive pulmonary disease, renal failure, heart failure, diabetes, stroke. A reduced HRV has been identified as a strong indicator of risk related to adverse events in healthy individuals and patients with a large number of diseases, reflecting the vital role that ANS plays in maintaining health. In diseases such as hypertension, acute myocardial infarction, coronary artery disease and atherosclerosis, HRV indexes are reduced. The assessment of HRV has also been widely used in order to diagnose both physiological and psychological disorders. In sports medicine, for example, is generally used to assess adaptations related to resistance training. The regular practice of physical activity has been reported as a factor in increased vagal tone due to physiological adaptations that have occurred by the increase in cardiac work, since there is a decreased sensitivity of beta receptors. Thus, the increase in parasympathetic modulation induces an electrical stability of the heart, while the high sympathetic activity increases the vulnerability of the heart and the risk of cardiovascular events. Despite the widespread use of HRV analysis in understanding the phenomena involved with the SNA in normal and pathological conditions, studies related to its use in clinical practice are still scarce. However, some studies have shown the great potential that HRV analysis can have in clinical practice. HRV has gained importance today as a technique to explore the ANS, which has an important role in maintaining homeostasis. The widest possible use, the cost-effectiveness in the application of the technique and ease of data acquisition makes the HRV an interesting option for interpretation of the functioning of the ANS and a promising clinical tool to assess and identify impairments on health.