Impacto de las estrategias de ejercicio físico en la disfunción endotelial inducida por conducta sedentaria

Abstract

Currently, sedentary behavior has gained recognition as a modifiable risk factor of significant importance, to which individuals are exposed in all aspects of their daily lives. Several studies highlight its close association with the risk of overall and cardiovascular mortality, as well as with cardiometabolic diseases and disorders of vascular endothelial function. In this context, it has been demonstrated that sedentary behavior leads to acute endothelial dysfunction, which with repetitive episodes and prolonged exposures can progress to a chronic condition. This situation is particularly significant, given that endothelial dysfunction is regarded as a precursor in the development of atherosclerotic diseases and other cardiovascular conditions. In fact, it has been described that a 1% loss in endothelial function would increase the risk of cardiovascular diseases by 13%. Consequently, measures aimed at preserving endothelial health through the management of sedentary behavior could play a central role in the prevention of these pathologies. Numerous studies have assessed the impact of different physical exercise strategies to counteract the effects of sedentary behavior on endothelial function. These strategies are primarily based on two approaches: interrupting sedentary time and engaging in exercise prior to sedentary behavior. The results of these trials have demonstrated variability in efficacy, effect size, and prescribed exercise modalities, thus becoming subjects of controversy. In this regard, given the methodological characteristics of the studies, it has been both interesting and relevant to undertake a systematic organization of information and conduct effect size stimations for variables primarily linked to endothelial function. This is aimed at contributing to a better understanding of this tool in the preventive context and facilitating the formulation of clinical recommendations or exercise prescription guidelines targeted towards individuals highly exposed to this risk factor. Considering these background facts, the overarching objective of this thesis has been to assess the potential impact of physical exercise on preventing acute endothelial dysfunction induced by sedentary behavior in adults, through two systematic reviews with meta-analyses of studies employing randomized controlled trial design. Within this context and to achieve this aim, three specific objectives were formulated: - To assess the current body of knowledge regarding the potential efficacy of strategies to interrupt sedentary time through physical exercise in the prevention of acute endothelial dysfunction caused by sedentary behavior in adults, through a qualitative and quantitative analysis of flow-mediated vasodilation, shear stress, and blood flow. - To assess the current scientific evidence regarding the potential efficacy of prior aerobic exercise in preventing the acute impairment of endothelial function caused by sedentary behavior in adults, through a qualitative and quantitative analysis of flow-mediated vasodilation, shear stress, and blood flow. - To determine if aerobic physical exercise prior to exposure to sedentary behavior has an effect on hemodynamic parameters, specifically heart rate and blood pressure, in adults. In the two studies conducted to achieve these objectives, a comprehensive analysis was conducted, encompassing both qualitative and quantitative assessments of the information extracted from the selected trials. These trials included adult individuals aged over 18 years who were subjected to either of the two strategic exercise approaches. The results obtained in this doctoral thesis revealed that physical exercise strategies appear to have a preventive impact on endothelial dysfunction induced by sedentary behavior. Specifically, it has been demonstrated that strategies involving interruptions of sedentary time through physical exercise appear to be efficacious in preventing acute endothelial dysfunction caused by sedentary behavior in adults. Additionally, it has been found that prior aerobic exercise was efficacious in preventing acute deterioration of endothelial function induced by sedentary behavior in adult individuals. The findings from both studies have reflected the favorable impact of physical exercise on the three key variables associated with endothelial function, namely flow-mediated vasodilation, shear rate, and blood flow. Furthermore, it has been observed that prior aerobic exercise seems to affect central hemodynamic parameters, resulting in a reduction in mean blood pressure during the first and third hours of sedentary behavior and an increase in heart rate during the first hour. The main conclusions were, firstly, that prior aerobic exercise has a slightly lesser effect than interruption strategies of sedentary behavior; however, it remains equally significant in counteracting the effects of sedentary behavior on endothelial function. Secondly, despite the existence of favorable results in favor of implementing these exercise strategies, the quality of evidence was estimated as moderate. Therefore, further research, including experimental studies and/or high-quality methodological clinical trials, is necessary in this area to reinforce the achieved results and conclusions. Nevertheless, even in its preliminary stages, these findings could potentially be applied to clinical practice guidelines for the prevention of endothelial dysfunction caused by sedentary behavior.