Free-living and in-lab effects of sedentary time on cardiac autonomic nervous system function in youth with overweight/obesity

项目摘要 心血管疾病(CVD)是一个重大的公共卫生负担，仍然是导致死亡的主要原因 在美国人口中。心血管疾病的进展可能始于儿童时期，青少年超重和 肥胖(OW/OB)会增加患心血管疾病的风险。一种机制有助于 心血管疾病的发展是心脏自主神经系统(ANS)功能失衡。心脏ANS主治 心脏通过交感和副交感神经调节对日常状况的反应，在这种平衡中 交感神经和副交感神经系统的异常提示心脏ANS功能正常。然而，年轻人与 OW/OB表现为心脏交感神经调制的过度激活，这与 几种不利的健康后果。 对年轻人的研究表明，久坐时间(ST)的增加与心血管疾病风险的增加有关。然而，它是 尚不清楚ST段和心血管疾病之间的联系是否由于从体力活动转移到ST段的时间 或由于ST刺激的潜在生理过程。心脏ANS平衡下降可能在 ST段与心血管疾病风险相关，但很少有研究人员研究ST段与心脏疾病之间的关系 ANS起作用，没有人在一天内或一个人内部检查过关联，也没有在实验中 操纵延长ST段。了解ST与心脏ANS功能的关系可能会提供洞察力 促进缓解心血管疾病发展的方法，特别是在患有OW/OB的年轻人中，他们的病情明显 患心血管疾病的风险更高。 该项目旨在利用美国国立卫生研究院资助的久坐休息研究3(P.I. Britni Belcher博士；R01DK12333)阐明了ST和ST之间的观察和实验关系 在患有OW/OB的年轻人中，心脏ANS通过测量心率变异性来发挥作用。这个项目的第一阶段 将调查在习惯性状态下客观测量的ST段和心脏ANS功能之间的日常联系 条件。在第二阶段，该项目将有一个创新的实验组件来确定 连续7天ST段阻断对心脏ANS功能的急性影响 条件：1)连续坐着(SIT)，2)坐着，中间有3分钟的中等强度步行 30分钟(坐+走)，3)坐着，中间有一次18分钟的中等强度步行(例如)。

PROJECT ABSTRACT Cardiovascular disease (CVD) is a significant public health burden and remains the leading cause of mortality among the U.S population. CVD progression can originate during childhood, and youth with overweight and obesity (OW/OB) have an increased risk for CVD development. One mechanism that contributes to the development of CVD is imbalanced cardiac autonomic nervous system (ANS) function. The cardiac ANS governs the heart’s response to everyday conditions via sympathetic and parasympathetic modulation, in which balance of the sympathetic and parasympathetic systems indicates healthy cardiac ANS function. However, youth with OW/OB present overactivation of the sympathetic modulation of the heart, which is strongly associated with several adverse health outcomes. Studies in youth demonstrated that increased sedentary time (ST) is related to higher CVD risk. However, it is unknown whether the associations between ST and CVD are due to time displaced from physical activity to ST or due to underlying physiological processes stimulated by ST. Reduced cardiac ANS balance may be mediating the ST and CVD risk association, but few researchers have examined the associations between ST and cardiac ANS function, and none have examined associations within a day or within a person, and have not experimentally manipulated prolonged ST. Understanding the relationship of ST to cardiac ANS function may provide insight toward methodologies to alleviate CVD development, especially in youth with OW/OB who are at significantly higher risk for CVD. This project aims to leverage data collection opportunities from the NIH-funded Sedentary Breaks Study 3 (P.I. Dr. Britni Belcher; R01DK12333) to elucidate observational and experimental relationships between ST and cardiac ANS function via measures of heart rate variability in youth with OW/OB. The first phase of this project will investigate daily associations between objectively-measured ST and cardiac ANS function under habitual conditions. In the second phase, this project will have an innovative experimental component to determine the acute effects of interrupting ST on cardiac ANS function in-lab over seven consecutive days among three conditions: 1) continuous sitting (SIT), 2) sitting interrupted by 3-minute bouts of moderate-intensity walking every 30 minutes (SIT+WALK), and 3) sitting interrupted by a single 18-minute bout of moderate-intensity walking (EX).