OBJECTIVE:Prolonged sedentary behavior can acutely reduce peripheral and central vascular function,thereby increasing the risk of cardiovascular disease.Interrupting sedentary behavior may be a potential practical strategy to prevent vascular dysfunction caused by prolonged sitting.However,current research findings on its acute effects are inconsistent,and specific application recommendations have not yet been established.This study aims to perform a Meta-analysis on the acute effects of interrupting sedentary behavior on peripheral and central vascular function in adults and to explore its regulatory factors.METHODS:Following PRISMA reporting guidelines,literature search was conducted in March 2024 using the keywords of"interrupting,""sedentary,"and"vascular function"in the Web of Science Core Collection,PubMed,and China National Knowledge Infrastructure(CNKI)databases.Acute randomized crossover trials addressing the acute effects of interrupting sedentary behavior on peripheral and central vascular function in adults were included.Risk of Bias 2 developed by Cochrane was used to assess bias risk,and the Grading of Recommendations Assessment,Development,and Evaluation(GRADE)system was used to evaluate the evidence level.The"meta"and"metaphor"packages in R(version 4.2.0)were used for main effect aggregation(Hedge's g acted as the effect size indicator),publication bias testing,subgroup analysis,and regression analysis.RESULTS:Twenty-two randomized crossover trials involving 364 subjects(aged 21 to 70 years)were included.Meta-analysis results showed that compared with prolonged sitting,interrupting sedentary behavior acutely improved peripheral vascular blood flow volume(Hedge's g=0.48,95%confidence interval:0.14-0.82,P<0.01,I2=63%,low evidence level),shear stress(Hedge's g=0.65,95%confidence interval:0.37-0.93],P<0.01,I2=54%,moderate evidence level),and flow-mediated dilation(Hedge's g=0.43,95%confidence interval:0.15-0.72,P<0.01,I2=61%,moderate evidence level).Disease had a significant moderating effect on the main effect aggregation for blood flow volume(P=0.01 between subgroups),while the mode(P=0.01 between subgroups)and frequency(P=0.02 between subgroups)of interruptions had significant moderating effects on shear stress.Improvements in peripheral vascular shear stress from interrupting sedentary behavior were affected by age(β=-0.02,95%confidence interval:-0.03-0.01,P=0.09)and body mass index(β=-0.10,95%confidence interval:-0.18 to-0.02,P<0.01).Improvements in flow-mediated dilation were influenced by the total number of interruptions(β=-0.09,95%confidence interval:-0.17 to-0.01,P=0.03)and the duration of sitting during the control period(β=-0.21,95%confidence interval:-0.34 to-0.09,P<0.01).Each additional hour of sitting was associated with a 0.67%reduction in the acute improvement effect of flow-mediated dilation from interrupting sedentary behavior(P<0.01),and acute benefits disappeared when sitting control time exceeded 6 hours.A qualitative systematic review found that interrupting sedentary behavior did not significantly affect pulse wave velocity in various populations but could effectively prevent central vascular function decline in older adults due to prolonged sitting.CONCLUSION:Interrupting sedentary behavior acutely improves peripheral vascular blood flow volume(low evidence level),shear stress(moderate evidence level),and flow-mediated dilation(moderate evidence level)in adults and may prevent or protect against central vascular function decline in older adults due to prolonged sitting(very low evidence level).Characteristics of subjects(disease factors,sex,age,and body mass index),interruption intervention schemes(mode,frequency,total number of interruptions),and duration of sitting control all influence the acute improvement effects of interrupting sedentary behavior on vascular function.It is recommended that adults interrupt sedentary behavior with exercises involving large muscle groups,such as stair climbing,at high frequencies(e.g.,once every 40 minutes)with at least 5 minutes of moderate-to low-intensity activity each time,and limit the cumulative duration of prolonged sitting to no more than 6 hours per day.

Objective: To explore the intervention effects of high intensity interval training (HIIT) on glucose metabolism, cortisol (Cor), and sleep quality among college students with comorbid depressive symptoms and obesity, so as to provide a reference for improving sleep quality among college students with comorbid depressive symptoms and obesity. Methods: In March 2023, 45 college students with comorbid depressive symptoms and obesity were recruited and randomly assigned to an exercise group ( n =23) and a control group ( n =22) by random number table method. The exercise group received HIIT intervention for 12 weeks, three times a week, while the control group received no intervention. Blood samples were collected from participants to measure fasting insulin (FINS), fasting blood glucose (FBG), homeostatic model assessment of insulin resistance (HOMA-IR), Cor, and Pittsburgh Sleep Quality Index (PSQI) before and after intervention. Statistical analysis was performed using t-test, repeated measures analysis of variance (ANOVA), simple effect analysis. Results: The repeated measures ANOVA revealed statistically significant time×group interaction effects for body composition (weight, body mass index, percentage of body fat, fat mass, waist to hip ratio), depressive symptoms, PSQI scores and its subdimensions (subjective sleep quality, sleep onset time, sleep efficiency, sleep disorders, daytime dysfunction), as well as FBG, FINS, and HOMA-IR between the exercise group and control group before and after intervention ( F =7.10-53.38, all P <0.05). Simple effect analysis showed that compared to the control group, the exercise group demonstrated significant improvements in body composition (body mass index, fat mass, waist to hip ratio), depressive symptoms, PSQI scores and its sub dimensions (subjective sleep quality, sleep onset time, sleep efficiency, sleep disorders, daytime dysfunction), FBG, FINS, HOMA-IR, and Cor (all P <0.05). Conclusion HIIT can improve the sleep quality of college students with comorbid depressive symptoms and obesity by enhancing glucose metabolism and regulating Cor levels.

OBJECTIVE:Prolonged sedentary behavior can acutely reduce peripheral and central vascular function,thereby increasing the risk of cardiovascular disease.Interrupting sedentary behavior may be a potential practical strategy to prevent vascular dysfunction caused by prolonged sitting.However,current research findings on its acute effects are inconsistent,and specific application recommendations have not yet been established.This study aims to perform a Meta-analysis on the acute effects of interrupting sedentary behavior on peripheral and central vascular function in adults and to explore its regulatory factors.METHODS:Following PRISMA reporting guidelines,literature search was conducted in March 2024 using the keywords of"interrupting,""sedentary,"and"vascular function"in the Web of Science Core Collection,PubMed,and China National Knowledge Infrastructure(CNKI)databases.Acute randomized crossover trials addressing the acute effects of interrupting sedentary behavior on peripheral and central vascular function in adults were included.Risk of Bias 2 developed by Cochrane was used to assess bias risk,and the Grading of Recommendations Assessment,Development,and Evaluation(GRADE)system was used to evaluate the evidence level.The"meta"and"metaphor"packages in R(version 4.2.0)were used for main effect aggregation(Hedge's g acted as the effect size indicator),publication bias testing,subgroup analysis,and regression analysis.RESULTS:Twenty-two randomized crossover trials involving 364 subjects(aged 21 to 70 years)were included.Meta-analysis results showed that compared with prolonged sitting,interrupting sedentary behavior acutely improved peripheral vascular blood flow volume(Hedge's g=0.48,95%confidence interval:0.14-0.82,P<0.01,I2=63%,low evidence level),shear stress(Hedge's g=0.65,95%confidence interval:0.37-0.93],P<0.01,I2=54%,moderate evidence level),and flow-mediated dilation(Hedge's g=0.43,95%confidence interval:0.15-0.72,P<0.01,I2=61%,moderate evidence level).Disease had a significant moderating effect on the main effect aggregation for blood flow volume(P=0.01 between subgroups),while the mode(P=0.01 between subgroups)and frequency(P=0.02 between subgroups)of interruptions had significant moderating effects on shear stress.Improvements in peripheral vascular shear stress from interrupting sedentary behavior were affected by age(β=-0.02,95%confidence interval:-0.03-0.01,P=0.09)and body mass index(β=-0.10,95%confidence interval:-0.18 to-0.02,P<0.01).Improvements in flow-mediated dilation were influenced by the total number of interruptions(β=-0.09,95%confidence interval:-0.17 to-0.01,P=0.03)and the duration of sitting during the control period(β=-0.21,95%confidence interval:-0.34 to-0.09,P<0.01).Each additional hour of sitting was associated with a 0.67%reduction in the acute improvement effect of flow-mediated dilation from interrupting sedentary behavior(P<0.01),and acute benefits disappeared when sitting control time exceeded 6 hours.A qualitative systematic review found that interrupting sedentary behavior did not significantly affect pulse wave velocity in various populations but could effectively prevent central vascular function decline in older adults due to prolonged sitting.CONCLUSION:Interrupting sedentary behavior acutely improves peripheral vascular blood flow volume(low evidence level),shear stress(moderate evidence level),and flow-mediated dilation(moderate evidence level)in adults and may prevent or protect against central vascular function decline in older adults due to prolonged sitting(very low evidence level).Characteristics of subjects(disease factors,sex,age,and body mass index),interruption intervention schemes(mode,frequency,total number of interruptions),and duration of sitting control all influence the acute improvement effects of interrupting sedentary behavior on vascular function.It is recommended that adults interrupt sedentary behavior with exercises involving large muscle groups,such as stair climbing,at high frequencies(e.g.,once every 40 minutes)with at least 5 minutes of moderate-to low-intensity activity each time,and limit the cumulative duration of prolonged sitting to no more than 6 hours per day.