| Objective:In this study,we investigated the association of different patterns,combinations and isotemporal substitutions of physical activity(PA)and sedentary behavior(SEB)with physical health in community-dwelling older women using objective measures,in order to provide theoretical evidence and practical guidance to encourage and guide the active participation of older people in PA.Methods:(1)This is a cross-sectional study.Older women aged 60-70 were recruited based on community centers and questionnaires were used to collect demographic data(age,living alone,education,alcohol use,medication use)and cognitive ability scores.(2)PA and SEB were assessed by 7-day wearing of triaxial accelerometer and were classified as moderate-intensity PA(moderate-to-vigorous PA),light-intensity PA(light intensity PA),sporadic PA(a continuous PA that lasts less than 10 minutes),bouted PA(a continuous PA that lasts equal to or more than 10 minutes),30min-bouted SEB(a continuous SEB that lasts equal to or more than 30 minutes)and 60min-bouted SEB(a continuous SEB that lasts equal to or more than 60 minutes).In addition,different combinations of PA and SEB were classified as low MVP A with high SEB,low MVPA with low SEB,high MVPA with high SEB and high MVPA with low SEB depending on time volume engaging in MVPA and SEB per day.(3)The assessment of physical health was based on Standards Handbook of National Measurement of Physical Health for Older Adult.A total of 6 items were tested to assess physical health,including body mass index,sit-and-reach,vital capacity,hand grip strength,choice reaction time and single-leg standing with eyes closed.Each item was scored from 1 to 5 and the sum score of all items was defined as the overall physical health score.All participants were classified as two groups(overall physical health score less than 15,equal to or more than 15).(4)Non-parametric tests were used to analyze the differences in multiple variables between groups.Pearson correlation analysis was used to explore the univariate correlation between PA,SEB with physical health in older adults.Multivariate-adjusted binary logistic regression was used to examine the association of different patterns and combinations of PA and SEB with physical health.Restricted cubic splines were used to explore the nonlinear relationship between MVPA and physical health levels,and isotemporal substitution models were used to explore the relationship between mutual substitution among LPA,SEB,and MVPA and physical health in older women.Results:(1)Of the 1124 older women included in the analysis,72 have an overall physical health score less than 15.The pass rate of all participants was 93.6%.Significant differences were found in education,MMSE score,daily sporadic LPA,total MVPA,sporadic MVPA,and bouted MVPA between groups(P<0.05),no group differences were found between other variables(P>0.05).(2)In our study,older women spent about 9 hours,5.1 hours and 33 minutes per day engaging in SEB,LPA and MVPA,respectively.About 70%of older women met the WHO recommendation of at least 150 minutes of MVPA per week.Simple correlation analysis revealed that all PA variables except bouted LPA were significantly and positively correlated with physical health scores of older women(P<0.05).In SEB variables,only 30min-bouted SEB was significantly and negatively correlated with physical health scores of older women(p<0.05).(3)Logistic regression analysis of associations between different PA and SEB patterns with physical health found that total MVPA,sporadic MVPA,total LPA,sporadic LPA and bouted LPA were found to be significantly associated with higher physical health level(P<0.05),total SEB and 30min-bouted SEB were significantly associated with lower physical health level(P<0.05),no association was observed between bouted MVPA and 60min-bouted SEB with physical health(P>0.05).(4)Analysis of joint associations of PA and SEB with physical health showed that,the combinations of high MVPA with high SEB,high MVPA with low SEB were both found to be significantly related to higher physical health level(P<0.05),which means that regardless of the amount of SEB,taking a high amount of MVPA can bring physical health benefits.(5)Restricted cubic splines analysis showed that,daily total MVPA time and low physical health level of older women showed a non-linear relationship with an approximate L-shaped curve.When total MVPA reaches 30 min per day,the decline of the curve gradually flattens out.(6)Isotemporal substitution model showed that,reallocating time to SEB,LPA and MVPA from each other were all significantly associated with physical health level.When using SEB to replace the same amount of LPA and MVPA,the OR of low physical health increased significantly(P<0.05).After using MVPA to replace the same amount of SEB and LPA,the OR of low physical health decreased significantly(P<0.05).When using LPA to replace the same amount of SEB and MVPA,the OR of low physical health significantly increased and decreased,respectively(P<0.05).Conclusions:(1)There were significant "dose-response" associations between PA,SEB and physical health in older women.Regardless of intensity(LPA,MVP A)and patterns(sporadic PA,bouted PA),physical health benefits can be gained by engaging in a certain amount of PA;(2)MVPA is high-efficiency in promoting physical health of older women,and engaging in 30 minutes of MVPA per day is most effective to achieve physical health benefits;(3)SEB,especially a prolonged SEB which lasts longer than 30 min,is significantly associated with the physical health decrease of older women;(4)Regardless of the amount of SEB,older women can gain physical health benefit as long as they engage in a high amount of MVPA;(5)Older women can gain significant physical health benefits by replacing the same amount of SEB and LPA with MVPA,but not with SEB.Replacing SEB with LPA can also obtain physical health benefits,but the effect is inferior to MVPA. |
