Abstract: Background Prolonged sitting can acutely impair peripheral and central vascular function and may further increase the risk of cardiovascular disease. Breaking up prolonged sitting is a low-barrier behavioral intervention strategy that can be readily integrated into daily life and community health management. This approach may attenuate the acute adverse vascular responses induced by prolonged sitting. However, existing evidence has been derived primarily from adults with healthy body weight. Studies examining the acute vascular effects of sitting interruptions in adults with overweight or obesity remain fragmented, and high-quality quantitative synthesis remains limited. Objective This systematic review and meta-analysis aimed to investigate the acute effects of breaking up prolonged sitting on vascular function in adults with overweight or obesity and to explore the potential influence of participant characteristics and intervention parameters on these effects. Methods PubMed, Web of Science, the Cochrane Library, Scopus, Embase, and the China National Knowledge Infrastructure(CNKI) were systematically searched from inception to November 2025. Eligible studies included adults aged ≥ 18 years with overweight or obesity, defined as a body mass index (BMI) ≥ 25.0 kg/m2 , and used randomized crossover controlled designs to assess acute intervention effects. Eligible interventions involved interrupting prolonged sitting with brief bouts of standing, walking, or low-load activities, such as brisk walking or simple resistance activities. Effect sizes were calculated from within-participant comparisons using Hedges' g as the standardized effect size. According to prespecified rules, data from the end of the exposure period, or from the time point closest to the end of exposure, were prioritized. Because individual studies could report multiple vascular outcomes, measurement time points, or effect sizes, a three-level random-effects model was used to pool effect sizes while accounting for within-study dependence among multiple effect sizes. Subgroup analyses and meta-regression were conducted to examine whether participant characteristics and intervention parameters influenced intervention effects and to identify potential sources of between-study heterogeneity. Results Eighteen randomized crossover trials involving 335 participants, including 167 men and 168 women, were included. Individual study sample sizes ranged from 10 to 25 participants, and participant age ranged from 21 to 78 years. Compared with uninterrupted sitting, sitting interruptions acutely reduced mean arterial pressure (MAP; g=-0.45,95%CI=-0.89 to -0.01, P=0.04; very low-certainty evidence), increased peripheral blood flow (g=0.28, 95%CI=0.01 to 0.55, P=0.04; low-certainty evidence), and improved flow-mediated dilation (FMD; g=0.56, 95%CI=0.05 to 1.06, P=0.03; very low certainty evidence). Evidence for acute effects on peripheral shear rate/shear stress (g=0.37, 95%CI=-0.10 to 0.84, P=0.12; very low-certainty evidence) and central vascular function markers (g=0.07, 95%CI=-0.32 to 0.46, P>0.05; low-certainty evidence) was uncertain. For peripheral pulse wave velocity, very low-certainty evidence did not support a definitive conclusion regarding acute improvement. Prespecified subgroup analyses and exploratory meta-regression suggested that MAP reductions were greater in older participants and those with higher BMI, and that more frequent interruptions and longer total interruption duration were associated with greater MAP reductions. Increases in peripheral blood flow were positively associated with the duration of the uninterrupted sitting control period. Improvements in FMD were associated with interruption timing parameters and exercise intensity, with shorter interruption bouts and moderate-intensity activities potentially corresponding to greater FMD improvements (P < 0.05). These exploratory findings mainly indicate potential sources of between-study heterogeneity and may inform future study design; they should be interpreted cautiously. Overall certainty of evidence ranged from low to very low, primarily because of risk of bias, inconsistency, and imprecision. Conclusions Compared with uninterrupted sitting, breaking up prolonged sitting may reduce MAP, increase peripheral blood flow, and improve FMD in adults with overweight or obesity. However, its acute effects on peripheral shear rate/shear stress, central vascular function, and peripheral pulse wave velocity remain uncertain. Because the available evidence is mostly of low to very low certainty and all outcomes were acute surrogate markers of vascular function, the current findings cannot be directly extrapolated to long-term cardiovascular clinical benefits. Results from prespecified subgroup analyses and exploratory meta-regression should be considered hypothesis-generating and used only as reference points for future study design.

Key words: Overweight, Obesity, sitting interruptions, overweight and vascular function, acute effects, three-level meta-analysis

摘要： 背景 持续久坐可在急性层面引发外周及中枢血管功能的不利改变，并可能进一步增加心血管疾病发生风险。久坐间断是一种便于融入日常生活和社区健康管理场景的行为干预策略，有可能缓解持续久坐诱发的急性血管不利反应。然而，既往相关证据多来自健康体重成人，针对超重与肥胖成人血管功能急性效应的研究仍较为零散，尚缺乏系统、高质量的定量综合证据。目的 本系统综述与荟萃分析旨在探讨久坐间断对超重与肥胖成人血管功能的急性影响，并探索受试者特征及干预参数对干预效应的潜在影响。方法 系统检索PubMed、Web of Science、Cochrane Library、Scopus、Embase与中国知网（建库至2025年11月）。纳入≥18岁、BMI≥25.0 kg/m2 的超重与肥胖成人；研究设计为针对急性干预效应的随机交叉对照试验；干预措施为在持续久坐过程中插入短暂站立/步行或低负荷活动（如快走、抗阻）等“久坐间断”方式。效应量基于受试者内对比构建，采用Hedges'g作为标准化效应量指标，并按预设规则优先选取暴露末端或最接近暴露末端的主时间点。考虑到同一研究可能报告多个血管功能结局、多个测量时间点或多个效应量，本研究采用三水平随机效应模型合并效应量，以处理同一研究内多效应量之间的非独立性。通过亚组分析与元回归分析，探索受试者特征及干预方案参数对干预效应的影响，明确研究间异质性的来源。结果 共纳入18项随机交叉试验，共包括335名参与者，其中男167名、女168名。单项研究样本量为10~25名，受试者年龄范围为21~78岁。与持续久坐相比，久坐间断能急性降低平均动脉压（MAP）（g=-0.45，95%CI=-0.89~-0.01，P=0.04；非常低确定性证据），增加外周血流量（g=0.28，95%CI=0.01~0.55，P=0.04；低确定性证据）及改善血流介导的血管舒张（FMD）（g=0.56，95%CI=0.05~1.06，P=0.03；非常低确定性证据）。对外周剪切应力（g=0.37，95%CI=-0.10~0.84，P=0.12；非常低确定性证据）与中枢血管功能指标（g=0.07，95%CI=-0.32~0.46，P>0.05；低确定性证据）的急性影响证据不确定；外周脉搏波速度（非常低确定性证据）总体未形成明确急性改善结论。预设亚组与探索性元回归分析显示，MAP降低幅度在年龄较大、BMI较高的受试者中更明显，且间断次数较多、总间断持续时间较长时MAP降低幅度更大；外周血流量增加幅度与试验期久坐控制时间呈正相关；FMD改善幅度与间断时间参数及运动强度有关，其中较短间断时间和中等强度间断活动可能对应更明显的FMD改善（P<0.05）。上述探索性结果主要用于提示研究间异质性的可能来源，可为后续研究设计提供参考线索，需谨慎解释。总体证据确定性为低至非常低，主要受偏倚风险、不一致性和不精确性影响。结论 久坐间断相较持续久坐可能有利于超重与肥胖成人MAP下降、外周血流量增加及FMD改善，但对外周剪切应力、中枢血管功能和外周脉搏波速度的急性影响仍不确定。由于现有证据多为低至非常低确定性，且结局均为急性血管功能替代指标，当前结果不能直接推断长期心血管临床获益。预设亚组和探索性元回归结果仅可作为后续研究设计的参考线索。

关键词: 超重, 肥胖, 久坐间断, 血管功能, 急性效益, 三水平荟萃分析