Aging can be characterized by an organic and functional decrease, which is not related to disease, that is, a process that happens naturally over time. One of the markers of the aging process is telomeres, which consist of a complex of DNA sequences located at the ends of the chromosome, composed of protective proteins that have the function of protecting information from the DNA (genome), that is, telomeres are responsible for reconstructing the information lost during cell division due to the wear and tear of the chromosome ends. The telomere length may be shorter in some diseases, such as heart failure with reduced ejection fraction (HFREF) compared with healthy subjects.~The HFREF is a complex clinical syndrome of poor prognosis and high prevalence. Its characteristics include fatigue, dyspnea and intolerance to physical exertion due to reduction in cardiac output, concomitant with respiratory changes, weakness in peripheral muscles and incidence of depression. Exercise as a strategy for the treatment of heart failure (HF) can be effective in improving the quality of life, functional capacity and prognosis of the disease. In sedentary individuals who do not have HF, a natural reduction of telomeres occurs, which is associated with the early development of the aging process. Increasing or maintaining the size of telomeres can be a way to intervene in the aging process and thus slow the progression of HF, since one of its main functions is to protect the chromosome from cellular aging.~One of the most promising strategies for intervening in aging is the practice of physical exercise. However, the effects of physical exercise on the telomere length of individuals with HF are unknown. However, we know that physical exercise for HF shows positive results in relation to functional capacity, as measured by peak oxygen consumption (VO2peak). In addition, the improvement in functional capacity, increase in peak oxygen consumption (VO2peak), is directly related to the increase in telomere length. However, there is a lack of concise results in the literature regarding the chronic effects of aerobic exercise on the telomere length in subjects with HFREF.~Therefore, the aim of the present study will be to analyze and compare the chronic effects of aerobic exercise in subjects with HFREF on telomere length.~The specifics aims of this study are: to analyze and compare the chronic effects of aerobic exercise in individuals with HFREF in the following variables: Functional Capacity (Cardiopulmonary Exercise Testing); Echocardiographic Variables by Doppler echocardiogram; Endothelial Function measured by Flow-Mediated Dilation (FMD) of the Brachial Artery; Walking Ability measured by a Self-Selected Walking Speed Test (SSWST)~This is a randomized clinical trial, with two intervention groups that will be assessed pre and post intervention. The randomization sequence will be generated by REDCap and it will be performed by a participant not involved in the other study phases (principal investigators will be blinded).~For significance level of 5%, power of 80%, difference to be detected equal to the standard deviation of 0.0026, the sample size calculated is 10 patients for each group (20 in total). Considering 20% loss, it will be necessary to include 12 patients per group (24 patients in total).
The present study will analyze and compare the chronic effects of aerobic exercise in subjects with systolic heart failure on telomere length.