Heart rate variability as a marker for stress and cardiovascular risk in assymptomatic adults

Abstract

Heart rate (HR) displays rhythmic fluctuations, which are essential for maintaining homeostasis. The Heart Rate Variability (HRV) can be measured by analyzing RR interval of the electrocardiogram, a noninvasive, accurate and low cost method. This measure reflects the modulation of cardiac activity by the autonomic nervous system. This modulation has great significance in various clinical conditions, reflecting physiological and metabolic changes in the body. Thus, conditions that interfere with the sympatho/vagal balance can cause changes in HRV, which justifies its use as a tool for studying organic changes associated with aging, cardiovascular diseases, obesity and physical training . Stress is a major risk factor for cardiovascular diseases, and other chronic diseases. A major goal of current research on stress is to establish biomarkers that allow identifying it. Some mediators of the stress response coordinate physiological reactions that result in the response of fight or flight. When this is not possible, these same mediators promote adaptation to the new situation. This adaptation is not always successful or achieved by the body, and can lead to the onset of stress-related illnesses. However, there are few studies in the literature addressing the correlation of stress and other risk factors for cardiovascular disease with HRV. Besides, the correlations between HRV and cardiovascular risks in asymptomatic elderly and middle-aged adults have not been investigated. Therefore, the explanation of the physiological factors, environmental and behavioral determinants in the pathogenesis of these diseases is important to establish measures to minimize its installation and its negative effects in this population. The objective of this project is to establish a protocol to evaluate the association between heart rate variability with chronic stress and cardiovascular risk factors in asymptomatic elderly population. One hundred and fifty volunteers between 50 and 70 will be recruited. Individuals with Chagas disease, acute myocardial infarction, coronary artery disease will be excluded from the sample. Evidence of osteoarticular involvement, neuromuscular or metabolic which interfer with the exercises are also exclusion criteria for this study. Anthropometric, body composition and blood concentrations of glucose and lipids will be evaluated. Heart rate data will be collected through Polar frequency counter and then analyzed by software Kubios for determining the heart rate variability (HRV). The use of the ramp protocol during cardiopulmonary exercise test will assess exercise capacity by VO2 Max analysis. The concentration of salivary cortisol and Perceived Stress Questionnaire comprise the assessment of stress. (AU)