| Background and ObjectivesSedentary behavior,which may be defined as “any waking behavior characterized by energy expenditure?1.5 metabolic equivalents(METs)while in a sitting or reclining posture”,exists generally in the modern living.Although studies on characteristic of sedentary behavior and its correlation with cardiovascular risk factors have yielded some good results,there are still many issues that need further exploration.And epidemiological research evidences show sedentarism is a lifestyle of accumulating much sedentary behavior,that jeopardizes the health of human beings,we need to take a new perspective to the study on methods and standards of estimating sedentarism.So far,there are few researches about “the association between sedentary behavior and cardiovascular risk factors”,so that the evidence for developing a health promotion strategy to breaks in sedentary time is limited.Therefore,this purpose of this study is to describe adults' the volume,patterns,and types of sedentary behavior,and determine the most important correlates of sedentary behavior,and examine the independent associations between volume,patterns,and types of sedentary behavior with cardiovascular risk factors.Subjects and Methods(1)Part one: To describe the time distributions of all types sedentary behaviors from 1054 adults who wore ActiGraph GT3 X accelerometers for ?5days and filled in activity log.Analysis of variance was performed to determine significant gender and age difference of sedentary time.Statistic chart were performed to describe the variation characteristics in daily and hourly of sedentary time.(2)Part two: Chi-square test was performed to describe the distributions of correlates variables from 1054 adults.Logistic regression models were used to determine the associations between prolonged sedentary behavior and correlates.(3)Part three: A total of 634 adults who had biological indicators were selected for the study.Chi-square test was performed to describe the distributions of the prevalence of risk factors abnormal between long and short sedentary time group.Logistic regression models were used to determine the associations between prolonged sedentary behavior and cardiovascular risk factors.Results(1)Amount of time spent in sedentary behaviors in adults living in urban areaOn average,participants engaged in 455.9 minutes sedentary behavior per day,sedentary behavior accounted for 48.9% of total wear time,the total number of sedentary bouts per day were 76.7.Time spent on TV viewing and computer use were 93.5minutes and 111.9 minutes,respectively.Time spent in sedentary behaviors did vary across every day,differences was statistically significant between weekend and weekday.Sedentary time was lowest during the morning and highest during the evening,the peak hours of sedentary behavior were in the afternoon(14:00-17:00)and in the evening(21:00-24:00).Sedentary time accumulated in ?1,?5,?10,?20,?30 minutes was significantly higher among men with the greatest difference observed in time spent in ?30 minutes bouts.Whether on weekday or weekend,men spend less TV viewing time than women,women spend less computer use time than men.The participants who was sedentarism,did meet the physical activity guidelines,took part in mainly screen-based sedentary behavior,and did not meet the physical activity guidelines,participant in diversification sedentary activities.(2)Correlates of sedentary behaviors in adults living in urban areaMore than one third of adults was evaluated as participants who participated in long sedentary behavior,long sedentary behavior bout,long TV viewing and long computer use,respectively.Among all potential correlates,age,occupational status,chronic diseases,health self-assessment,education,BMI,levels of PA and the numbers of TV and computer was strongly associated with prolonged sedentary behavior;gender,age,occupational status,chronic diseases,BMI,levels of PA and the numbers of juveniles in family was strongly associated with prolonged sedentary behavior bout;gender,occupational status,chronic diseases,health self-assessment,marital status and the numbers of TV and computer was strongly associated with prolonged TV viewing;occupational status,education,chronic diseases,BMI,levels of PA and the numbers of TV and computer was strongly associated with prolonged computer use.(3)Associations of sedentary behavior and breaks in sedentary time with cardiovascular risk factorsAfter adjustment for moderate-to vigorous-intensity physical activity,body mass index and other potential confounders,prolonged sedentary behavior was not significantly associated with cardiovascular risk factors;Sedentary time accumulated in bout of ?30 minutes was significantly associated with increasing risks of HDL cholesterol among men and diabetes among women.Prolonged TV viewing time was significantly associated with increasing risks of HDL cholesterol among women,Prolonged computer use time was not significantly associated with cardiovascular risk factors.After adjustment for moderate-to vigorous-intensity physical activity,total sedentary time,body mass index and other potential confounders,Prolonged time of interrupting sedentary behavior was significantly associated with reducing risks of HDL cholesterol among men and diabetes among women.Except for HDL cholesterol,the values of other cardiovascular metabolic indicators of SSB?LBSB was lower than other three groups,and the prevalence of risk factors abnormal was lower.ConclusionsSedentary time accumulated in bout of ?1 minutes was significantly higher among men,and women had significantly more ?1 minutes bouts and recreational screen-based time than did men.Adults tend to accumulate more sedentary time in bout of ?30 minutes,on weekdays and in the evening(21:00-24:00).Potential correlates differed according to sedentary behavior(volume,patterns,and types of sedentary behavior).the most importance correlates of sedentary behavior were occupational status,chronic diseases,BMI,and levels of PA,then the numbers of TV and computer.The more sedentary time the adults accumulated in bout of ?30 minutes,the poorer the glucose and lipid metabolism status.TV viewing time also had a negative effect on lipid metabolism for women.The longer time of interrupting sedentary behavior,the higher the HDL cholesterol level in men and the lower blood glucose level in women.In particular,it is more appropriate to the pattern of SSB?LBSB. |
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