Isotemporal Substitution Models Research Articles

The effect of replacing sedentary behavior with different intensities of physical activity on depression and anxiety in Chinese university students: an isotemporal substitution model

BackgroundPrevious research has suggested that engaging in regular physical activity (PA) can help to reduce symptoms of depression and anxiety in university students. However, there is a lack of evidence regarding the impact of reducing sedentary behavior (SB) and increasing light-intensity PA (LPA) on these symptoms. This study aims to address this gap by using isotemporal substitution (IS) models to explore how substituting SB with LPA or moderate-to-vigorous PA (MVPA) affects depression and anxiety symptoms among university students.MethodsThe study recruited 318 university students with a mean age of 21.13 years. Accelerometers were used to objectively measure the time spent on SB, LPA, and MVPA, while depression and anxiety symptoms were assessed using the Center for Epidemiologic Studies Depression Scale (CES-D) and the Self-rating Anxiety Scale (SAS). IS models using multivariable linear regression were employed to estimate the associations between different behaviors and depression and anxiety symptoms when 30 min of one behavior was substituted with another.ResultsIn the single-activity model, less SB (β = 0.321, 95% CI: 0.089, 1.297) and more MVPA (β = −0.142, 95% CI: −1.496, − 0.071) were found to be significantly and negatively associated with depression scores, while less SB (β = 0.343, 95% CI: 0.057, 1.014), LPA (β = 0.132, 95% CI: 0.049, 1.023), and more MVPA (β = −0.077, 95% CI: −1.446, − 0.052) were significantly and negatively correlated with anxiety scores. The IS analysis revealed that substituting 30 min of SB with LPA (β = −0.202, 95% CI: −1.371, − 0.146) or MVPA (β = −0.308, 95% CI: −0.970, − 0.073) was associated with improvements in depressive symptoms. Substituting 30 min of SB with MVPA (β = −0.147, 95% CI: −1.863, − 0.034) was associated with reduced anxiety symptoms.ConclusionReplacing 30 min of SB with MVPA may alleviate depression and anxiety symptoms in university students. Further research is needed to explore the long-term effects of PA interventions on the mental health disorders of this population.

Accelerometer-Measured Physical Activity, Fitness and Indicators of Cardiometabolic Risk among Rural Adolescents: A Cross-Sectional Study at 15-Year Follow-up of the MINIMat Cohort.

Little is known about the relationship of physical activity (PA) and fitness with cardiometabolic risk among rural adolescents in low- and middle-income countries. Thus, we examined the associations of PA and fitness with selected cardiometabolic indicators along with potential gender-based differences in a birth cohort of rural adolescents from southeast Bangladesh. We utilized data from the 15-year follow-up of Maternal and Infant Nutrition Interventions in Matlab (MINIMat) cohort (n = 2253). Wrist-worn ActiGraph wGT3x-BT accelerometers were used to estimate sedentary time (ST) and PA. Fitness was assessed using: handgrip strength, standing long jump, and Chester Step Test. Anthropometric parameters, systolic blood pressure (SBP), and fasting lipid, insulin and glucose levels were measured. We calculated insulin resistance using the Homeostasis Model Assessment equation (HOMA-IR). Linear regression and isotemporal substitution models were fitted. The adolescents spent 64min/day (inter-quartile range: 50-81) in moderate-to-vigorous physical activity (MVPA). A 10-minute-per-day higher vigorous PA (VPA) was associated with: 4.9% (95% confidence interval (CI): 2.9-6.8%) lower waist circumference (WC), 3.2 mmHg (95% CI: 1.5-4.8) lower SBP, 10.4% (95% CI: 2.9-17.3%) lower TG, and 24.4% (95% CI: 11.3-34.9%) lower HOMA-IR. MVPA showed similar associations of notably smaller magnitude. Except for WC, the associations were more pronounced among the boys. Substituting ST with VPA of equal duration was associated with lower WC, SBP, triglyceride and HOMA-IR. Grip strength was favorably associated with all indicators, displaying considerably large effect sizes. Our findings indicated beneficial roles of PA- particularly VPA- and muscular fitness in shaping cardiometabolic profile in mid-adolescence. VPA and grip strength may represent potential targets for preventive strategies tailored to adolescents in resource-limited settings.

Associations between back pain incidence, and physical activity and sedentary behaviours: A prospective cohort study with data from over 365,000 participants.

OBJECTIVE: To examine the associations between (i) various types of physical activity and the risk of back pain incidence, and (ii) the influence of substituting sedentary behaviours with physical activities on back pain incidence. DESIGN: A prospective cohort study. METHODS: We analyzed UK Biobank data collected from 365,307 participants who were free of back pain at baseline. The exposures were total, light, moderate and vigorous physical activity, and sedentary behaviours. The outcome was back pain incidence. The main statistical models were the Cox proportional hazard model and the isotemporal substitution model. RESULTS: In the follow-up time (median, 12.97 years; inter-quartile range, 12.10-13.71), 25,189 individuals developed back pain. The associations between all types of physical activity and incident back pain were significantly non-linear (p < 0.001) among the general population and other subgroups. High physical activity was associated with a decreased risk of back pain compared with no physical activity. The lowest risk occurred in the 1801-2400 MET-min/week subgroup of total physical activity (HR 0.64, 95% CI 0.59-0.69), approximately consisting of 1200, 600, and 600 MET-min/week of light, moderate and vigorous physical activity, respectively. Extremely high vigorous physical activity was related to high risk, specifically in males (HR 1.13, 95% CI 1.02-1.25). Replacing 1 hour/day of sedentary behaviours with an equal time of physical activity reduced the risk of incident back pain by 2%-8% (p < 0.05). CONCLUSION: Physical activity was related to a reduced risk of back pain incidence (except over-high vigorous physical activity). Substituting sedentary behaviours with physical activities reduced the risk of future back pain.

Relationship between 24-h activity behavior and body fat percentage in preschool children: based on compositional data and isotemporal substitution analysis

ObjectiveThis study aims to elucidate the dose‒response relationship between 24-h activity behaviors and body fat percentage (BFP) in Chinese preschool children using a compositional isotemporal substitution model (ISM).MethodsIn a cross-sectional design, 881 children aged 3–6 from urban and rural areas of Jiangxi Province were sampled. Activity behaviors, including sedentary behavior (SB), low-intensity physical activity (LPA), and moderate- to high-intensity physical activity (MVPA), were measured using accelerometers. Sleep patterns were assessed through questionnaires, and BFP was determined by bioelectrical impedance analysis (BIA). The study employed compositional data analysis (CoDA) and ISM to estimate the impact of reallocating durations of different activity behaviors on BFP.ResultsHigher BFP was found in urban vs. rural children, decreasing with age. Overweight and obesity rates were 10.6% and 7.6%, respectively, above national averages. MVPA and LPA were negatively correlated with BFP, while SB was positively correlated.A 30-min MVPA reduction significantly increased zBFR, particularly in overweight children. Gender-specific nuances revealed that boys' MVPA negatively influenced zBFP (β = -0.155), P < 0.05), while girls' SB positively impacted zBFP (β = 0.636, P < 0.01). Isotemporal simulations emphasized amplified effects in overweight children, with boys' zBFR rising rapidly when MVPA was substituted and girls displaying a notable substitution effect between SB and LPA.ConclusionBFP is closely linked to 24-h activity behaviors, notably in overweight and obese preschoolers. ISM identified MVPA as a critical influencer, with a 30-min reduction substantially increasing BFP. Gender disparities were evident, implicating MVPA in boys and LPA and SB in girls.

Longitudinal associations of screen time, physical activity, and sleep duration with body mass index in U.S. youth

BackgroundYouth use different forms of screen time (e.g., streaming, gaming) that may be related to body mass index (BMI). Screen time is non-independent from other behaviors, including physical activity and sleep duration. Statistical approaches such as isotemporal substitution or compositional data analysis (CoDA) can model associations between these non-independent behaviors and health outcomes. Few studies have examined different types of screen time, physical activity, and sleep duration simultaneously in relation to BMI.MethodsData were baseline (2017–2018) and one-year follow-up (2018–2019) from the Adolescent Brain Cognitive Development Study, a multi-site study of a nationally representative sample of U.S. youth (N = 10,544, mean [SE] baseline age = 9.9 [0.03] years, 48.9% female, 45.4% non-White). Participants reported daily minutes of screen time (streaming, gaming, socializing), physical activity, and sleep. Sex-stratified models estimated the association between baseline behaviors and follow-up BMI z-score, controlling for demographic characteristics, internalizing symptoms, and BMI z-score at baseline.ResultsIn females, isotemporal substitution models estimated that replacing 30 min of socializing (β [95% CI] = -0.03 [-0.05, -0.002]), streaming (-0.03 [-0.05, -0.01]), or gaming (-0.03 [-0.06, -0.01]) with 30 min of physical activity was associated with a lower follow-up BMI z-score. In males, replacing 30 min of socializing (-0.03 [-0.05, -0.01]), streaming (-0.02 [-0.03, -0.01]), or gaming (-0.02 [-0.03, -0.01]) with 30 min of sleep was associated with a lower follow-up BMI z-score. In males, replacing 30 min of socializing with 30 min of gaming was associated with a lower follow-up BMI z-score (-0.01 [-0.03, -0.0001]). CoDA estimated that in males, a greater proportion of time spent in baseline socializing, relative to the remaining behaviors, was associated with a higher follow-up BMI z-score (0.05 [0.02, 0.08]). In females, no associations between screen time and BMI were observed using CoDA.ConclusionsOne-year longitudinal associations between screen time and BMI may depend on form of screen time, what behavior it replaces (physical activity or sleep), and participant sex. The alternative statistical approaches yielded somewhat different results. Experimental manipulation of screen time and investigation of biopsychosocial mechanisms underlying the observed sex differences will allow for causal inference and can inform interventions.

Effects of substituting sedentary time with physical activity on body mass index in Japanese adults with Down syndrome: A cross-sectional study

Objectiveand Rationale: Obesity is a health challenge for adults with Down syndrome. Therefore, a physical activity promotion program is required to prevent or reduce obesity in adults with this condition. However, there is a lack of evidence of useful risk reduction initiatives. The objective of this study was to suggest a rationale for behaviors that should replace time of inactivity to reduce obesity in Japanese adults with Down syndrome. MethodsThe participants were adults with Down syndrome, aged 18–48 years, living in Japan. The snowball sampling method was used. To detect an effect size of 0.20 for body mass index using an F-test, 80 participants were required, generating a statistical power of 0.8 and a risk level of 0.05. Survey items included sex, age, height, weight, body mass index, and physical activity (min/d). Physical activity was categorized by intensity and further divided into ambulatory and non-ambulatory activities. The body mass index categories were compared using analysis of covariance. An isotemporal substitution model was used to confirm the interdependence of behaviors. ResultsHalf of the participants were obese, with a body mass index of 25 kg/m2 or higher. The obese group had significantly fewer light physical activity, moderate-to-vigorous physical activity, and ambulatory moderate-to-vigorous physical activity times than the non-obese group. Replacing 10 min of sedentary behavior with ambulatory moderate-to-vigorous physical activity was significantly associated with a lower body mass index. ConclusionsThis study suggests a rationale for behaviors that should replace time of inactivity to reduce obesity in adults with Down syndrome. Specifically, replacing 10 min of sedentary behavior with ambulatory moderate-to-vigorous physical activity time may contribute to obesity reduction.

Association between accelerometer-derived physical activity and depression: a cross-sectional study using isotemporal substitution analysis

ObjectivesDepression is a significant public health concern, and physical activity has been identified as a non-pharmacological intervention. Understanding the dose–response relationship between physical activity and depression is crucial for designing...

The influence of habitual physical activity and sedentary behavior on objective and subjective hot flashes at midlife.

The purpose of this study was to evaluate relationships between physical activity, sedentary time, and hot flashes during both waking and sleeping periods using concurrent objective and subjective measures of hot flashes in midlife women. Women aged 45 to 55 years (n = 196) provided self-reported data on physical activity and underwent 24 hours of hot flash monitoring using sternal skin conductance. Participants used event marking and logs to indicate when hot flashes were perceived. Wake and sleep periods were defined by actigraphy. Mean ambient temperature and humidity were recorded during the study period. Generalized linear regression modeling was used to evaluate the effect of physical activity types and sedentary time on hot flash outcomes. Isotemporal substitution modeling was used to study the effect of replacing sedentary time with activity variables on hot flash frequency. Modeled results indicated that increasing sitting by 1 hour was associated with a 7% increase in the rate of objectively measured but not subjectively reported hot flashes during sleep. Replacing 1 hour of sitting with 1 hour of vigorous activity was associated with a 100% increase in subjectively reported but not objectively measured waking hot flashes. There was little evidence for an effect of temperature or humidity on any hot flash outcome. These data provide support for relations between sedentary time, physical activity, and hot flashes and highlight the importance of using objective and subjective assessments to better understand the 24-hour hot flash experience.

Replacing sedentary time for physical activity: Does intensity matter for body composition in oldest-old adults?

ABSTRACT To assess the independent and combined relationships among objectively measured sedentary time (ST), light intensity PA (LPA), and moderate-to-vigorous intensity PA (MVPA) with muscle mass and fat mass (FM) and how theoretical displacement of these inter-dependent behaviours relates to body composition in oldest-old men. A total of 1046 men participating in the year 14 visit of the prospective Osteoporotic Fractures in Men (MrOS) cohort study with complete data for accelerometry, dual x-ray absorptiometry, and deuterated creatine dilution (D3Cr) muscle mass were included in the analysis (84.0 ± 3.8 yrs.). Single, partition, and isotemporal substitution models were used to assess the interrelationships between PA intensities and ST with body composition measures, while controlling for relevant confounders. Replacing 30-min of ST with 30-min of MVPA was associated with lower FM (β =-0.17, p < 0.001) and higher D3Cr muscle mass, although this was of borderline significance (β = 0.07, p = 0.05). Replacing 30-min of ST for LPA was associated with lower FM (β =-0.15, p < 0.001), but there was no effect on D3Cr muscle mass (p > 0.05). Exchanging ST with any intensity of PA is associated with benefits for FM in oldest-old adult men, although substitution with MVPA may be more beneficial than LPA for maintaining/improving skeletal muscle mass.

Accelerometer-measured physical activity and sedentary behaviour are associated with C-reactive protein in US adults who get insufficient sleep: A threshold and isotemporal substitution effect analysis

ABSTRACT This study aimed to investigate the association between physical activity, sedentary behaviour and chronic inflammation in short sleep adults. The study included 2,113 NHANES participants with self-reported insufficient sleep. C-reactive protein (CRP) was used as the inflammatory biomarker. Physical activity and sedentary behaviour were objectively measured by accelerometers. Weighted regression model, two – piecewise linear regression model, and restricted cubic splines were applied to evaluate associations mentioned above. An isotemporal substitution model was used to assess the modelled effects of replacing sedentary time (ST) with moderate-to-vigorous levels of physical activity (MVPA) or light physical activity (LPA). After adjusting for potential confounding factors, higher levels of ST and lower levels of LPA or MVPA were associated with higher CRP levels. Isotemporal substitution analysis indicated that replacing 30 minutes of ST with 30 minutes of MVPA was associated with a significant decrease in CRP levels. Saturation analysis suggested that the association between MVPA and CRP may plateau at over 20 minutes of MVPA per day. Findings of this study provides insight into the potential benefits of replacing ST with MVPA. This study also suggests that increasing MVPA beyond a certain point may not provide additional anti-inflammatory benefits in a short sleep population.

Isotemporal substitution effect of 24-hour movement behavior on the mental health of Chinese preschool children.

The 24-h movement behavior of preschoolers comprises a spectrum of activities, including moderate-to-vigorous intensity physical activity (MVPA), light-intensity physical activity (LPA), screen-based sedentary behavior (SCSB), non-screen-based sedentary behavior (NSCSB), and sleep. While previous research has shed light on the link between movement behaviors and children's mental health, the specific impacts on the unique demographic of Chinese preschoolers remain underexplored. This study significantly contributes to the literature by exploring how 24-h movement behavior affects the mental health of preschoolers in a Chinese context. The study involved205 Chinese preschool children (117 boys and 88 girls) between the ages of 3 and 6 years wore accelerometers to measure their LPA, MVPA, and sedentary behavior (SB), while their parents reported the time spent on sleep and SCSB. The parents also completed the Strength and Difficulties Questionnaire to assess their children's mental health. The study used compositional regression and isotemporal substitution models to examine the relationship between the various components of 24-h movement behavior and mental health. The results showed that greater NCSSB compared to MVPA, LPA, sleep, and SCSB was associated with good prosocial behavior and lower scores on externalizing problems. This highlights the potential of NSCSB as a beneficial component in the daily routine of preschoolers for fostering mental well-being. Replacing 15 min of sleep and SCSB with 15 min of NSCSB was associated with a decrease of 0.24 and 0.15 units, respectively, in externalizing problems. Reallocating 15 min of sleep to NSCSB was linked to an increase of 0.11 units in prosocial behavior. There were no significant substitution effects between LPA and MVPA time with any other movement behavior on prosocial behavior and externalizing problems. Given the positive associations observed, further longitudinal studies are necessary to explore the link between 24-h movement behavior and mental health in preschool children.

Finding the balance: The influence of movement behaviours on childhood behaviour problems

Background and aimsThe Canadian 24-h movement guidelines have led to an increased focus on movement behaviours (sleep, screen, sedentary, and physical activity) throughout the day. MethodsWe examined the cross-sectional and longitudinal associations between 24-h movement behaviours and parent-reported levels of internalizing, externalizing, and total behaviour problems in a subset of the CHILD birth cohort study at ages 3 (N Age 3 = 541, 48.1% girls) through 5 (N Age 5 = 575, 49.6% girls). Physical activity, sedentary time, and sleep were measured using an accelerometer worn on the non-dominant wrist for seven days following a 24-h protocol. Screen time was measured via parent-report and date-matched to daily accelerometer recordings. Compositional isotemporal substitution models predicted change in behaviour problems with reallocating time between movement behaviours. ResultsCross-sectional analysis indicated that screen time relative to other movement behaviours was associated with greater externalizing behaviours at age 3 and greater internalizing and total problem behaviours at ages 3 and 5. This was supported in the longitudinal analysis, where increased screen time at 3 was associated with increased internalizing, externalizing, and total problem behaviours at 5. Cross-sectional reallocation from screen to non-screen sedentary time was associated with reductions in internalizing and total behaviour problems at 3 and 5 years and reductions in externalizing at 3. Contrary to previous findings, cross-sectional proportional increases in moderate-to-vigorous-intensity physical activity were associated with increased externalizing and total problem behaviours at 5. ConclusionsClinicians should prioritize supporting families to find a balanced approach rather than promoting specific movement behaviours.

Daily time spent on screens and psychological well-being: Cross-sectional association within the SUN cohort

BackgroundThe impact of various lifestyles on psychological well-being (PWB) remains under-studied. We aimed to explore the cross-sectional association between daily screen use (television, tablet and mobile phone) and PWB within the SUN cohort. MethodsPWB was assessed using the 29-item Ryff scale (ranging from 29 to 174), and participants with scores >75th percentile were considered as having optimal PWB. Participants were categorized based on their self-reported weekly screen usage hours. Postestimation logistic regression models assessing the prevalence likelihood of not achieving optimal PWB were adjusted for sociodemographic, psychological, personality and lifestyles factors. Isotemporal substitution models explored the potential impact on PWB resulting from replacing 1 h/day of screen time with 1 h/day of exercise. ResultsThe study included 3051 participants (55.8% women, mean age 57.3 ± 11.1 years, mean Ryff's score: 139.1 ± 17.4 points). Daily screen use for ≥2 h was associated with a higher prevalence likelihood of not achieving an optimal PWB (Prevalence Ratio [PR]:1.09; 95% CI:1.01–1.18). Among PWB dimensions, screen use ≥2 h/day was linked to an increased likelihood of not achieving optimal scores in environmental mastery (PR:1.11; 95% CI:1.02–1.20), life purpose (PR:1.10; 95% CI:1.02–1.18), and personal growth (PR:1.09; 95% CI:1.01–1.18). Replacing 1 h of daily screens time with 1 h of exercise may lead to potential improvements in environmental mastery (Odds Ratio [OR]:0.87; 95% CI:0.76–0.99), purpose in life (OR:0.86; 95% CI: 0.76–0.98), personal growth (OR:0.84; 95% CI:0.73–0.96) and positive interpersonal relationships (OR:0.86; 95% CI:0.75–0.99). ConclusionsThese findings highlight the importance of reducing screen use activities and increasing physical exercise for achieving optimal PWB.

Associations between Parental Educational Attainment, Children's 24-h Behaviors and Children's Hyperactivity Behavior in the COVID-19 Pandemic.

Parental Educational Attainment and children's 24-h behaviors significantly influenced children's hyperactivity symptoms. This study aimed to examine the mediating role of children's 24-h behavior changes due to the COVID-19 pandemic between Parental Educational Attainment and children's hyperactivity index. It also aimed to investigate the associations between Children's Physical Activity, digital media use, sleep, and hyperactivity index between two clusters of Parental Educational Attainments. The goal was to provide targeted behavioral optimization recommendations for caregivers to reduce the risk of children's hyperactivity. The study was a collaborative extension of the International iPreschooler Surveillance Study Among Asians and otheRs project and the Chinese Children and Adolescent Sports Health Promotion Action Project. The Parent-Surveillance of Digital Media in Childhood Questionnaire® and the Abbreviated Rating Scales from the Conners Parent Symptom Questionnaire were used to measure Parental Educational Attainment, children's behavior changes during the COVID-19 pandemic, and hyperactivity indexes. A total of 11,190 parents of 6-to-12-year-old children completed the online surveys in mainland China. A structural equation model was established by using Smart-PLS, and the linear regression model, and isotemporal substitution models were established by using a Compositional Data Analysis package with R program to achieve the research objectives. Changes in children's 24-h behaviors due to the COVID-19 pandemic had a significant mediation effect on the negative associations between Parental Educational Attainment and children's hyperactivity index (β = 0.018, T = 4.521, p < 0.001) with a total effect (β = -0.046, T = 4.521, p < 0.001) and a direct effect (β = -0.064, T = 6.330, p < 0.001). Children's Digital Media use was significantly and negatively associated with hyperactivity index among all children. Reallocated time from digital media use to both sleep and physical activity decreased the hyperactivity index, and vice-versa. For parents without tertiary education (R2 = 0.09, p < 0.001), sleep was significantly and negatively associated with the hyperactivity index (βilr-CSL = -0.06, p < 0.001); for parents with tertiary education (R2 = 0.07, p < 0.001), physical activity was significantly and negatively associated with the hyperactivity index (βilr-CPA = -0.05, p < 0.001), and sleep was significantly and positively associated with the hyperactivity index (βilr-CSL = 0.03, p < 0.001). A significant increase in the hyperactivity index was detected when physical activity time was reallocated to sleep, with a significant decrease in the opposite direction. Parental Educational Attainment and children's 24-h behaviors directly influenced children's hyperactivity index. However, a purposeful and targeted optimization of children's 24-h behaviors-namely, physical activity, digital media use, and sleep-could assist parents with different educational attainments to reduce their children's hyperactivity index and mitigate the risk of hyperactivity.

Accelerometer-measured physical activity, sedentary behavior, and risk of incident pelvic organ prolapse: a prospective cohort study in the UK Biobank

BackgroundPrevious studies on physical activity (PA) and pelvic organ prolapse (POP) were largely limited to self-reported PA in athletes, soldiers, and women in postpartum. We aimed to investigate the association of accelerometer-measured PA and sedentary behavior with the risk of POP in middle-aged and elderly women.MethodsIn this prospective cohort derived from the UK Biobank, the intensity and duration of PA and sedentary behavior were measured with wrist-worn accelerometers over a 7-day period in 2013–2015 for 47,674 participants (aged 42.8–77.9 years) without pre-existing POP. Participants were followed up until the end of 2022, during which incident POP was ascertained mainly by the electronic health records. Multivariable-adjusted Cox proportional hazards models and restricted cubic splines were used to assess the associations of interest. Isotemporal substitution models were applied to test the effects of substituting a type of activity with equivalent duration of others.ResultsDuring a median follow-up of 8.0 years, 779 cases of POP were recorded. The duration of light-intensity PA (LPA) was positively whereas sedentary time was negatively associated with the risk of POP. Every additional 1 h/day of LPA elevated the risk of POP by 18% (95% confidence interval [CI], 10%–26%). In contrast, the risk decreased by 5% (95% CI, 0–8%) per 1 h/day increment in sedentary behavior. No associations were found between moderate-intensity PA (MPA) or vigorous-intensity PA (VPA) and POP, except that women who had a history of hysterectomy were more likely to develop POP when performing more VPA (53% higher risk for every additional 15 min/day). Substituting 1 h/day of LPA with equivalent sedentary time was associated with a 18% (95% CI, 11%–24%) lower risk of POP. The risk can also be reduced by 17% (95% CI, 7%–25%) through substituting 30 min/day of LPA with MPA.ConclusionsMore time spent in LPA or less sedentary time was linked to an elevated risk of POP in middle-aged and elderly women, while MPA or VPA was not. Substituting LPA with equivalent duration of sedentary behavior or MPA may lower the risk of POP.

Behavior reallocations within 24-h movement profiles and change in cardiometabolic biomarkers during pregnancy.

The goal of this study was to investigate associations of reallocations within 24-h movement profiles and changes in cardiometabolic biomarkers from early to late pregnancy. In 137 individuals with prepregnancy overweight/obesity, waking movement was measured using wrist-worn accelerometers, sleep was self-reported, and biomarkers were measured in fasting serum samples at 12 and 32 weeks' gestation. We used compositional isotemporal substitution models. On average, biomarkers increased 21%-83% across pregnancy. For those with guideline-recommended moderate/vigorous-intensity physical activity (MVPA) in early pregnancy, reallocating 30 min from MVPA to sleep, sedentary behavior, or light-intensity physical activity (LPA) was associated with a 0.6 mmol/L greater increase in total cholesterol (95% CI: -0.1 to 1.2) and a 0.7 mmol/L greater increase in low-density lipoprotein (LDL) cholesterol (95% CI: 0.1 to 1.3) from early to late pregnancy. For those with low MVPA in early pregnancy, reallocating 30 min from sleep, sedentary behavior, or LPA to MVPA was associated with a 0.6 mmol/L lower increase in total cholesterol (95% CI: -1.3 to 0.1) and a 0.8 mmol/L lower increase in LDL cholesterol (95% CI: -1.4 to -0.1) from early to late pregnancy. There were no associations with change in glucose, insulin, homeostatic model assessment for insulin resistance, very low-density lipoprotein, or high-density lipoprotein cholesterol, triglycerides, or free fatty acids. Maintaining or achieving a 24-h movement profile with guideline-recommended amounts of MVPA may be beneficial for reducing pregnancy-induced increases in total and LDL cholesterol.

Reallocating time between device-measured 24-hour activities and cardiovascular risk in Asian American immigrant women: An isotemporal substitution model.

The 24-hour day consists of physical activity (PA), sedentary behavior, and sleep, and changing the time spent on one activity affects the others. Little is known about the impact of such changes on cardiovascular risk, particularly in Asian American immigrant (AAI) women, who not only have a higher cardiovascular risk but also place greater cultural value on family and domestic responsibilities compared to other racial/ethnic groups. The purpose of this study was to evaluate the effects of reallocating 30 minutes of each 24-hour activity component for another on BMI, waist circumference, and blood pressure in AAI women. Seventy-five AAI women completed 7 days of hip and wrist actigraphy monitoring and were included in the analysis (age = 61.5±8.0 years, BMI = 25.5±3.6 kg/m2, waist circumference = 85.9±10.2 cm). Sleep was identified from wrist actigraphy data, and moderate-to-vigorous PA (MVPA), light PA, and sedentary behavior identified from hip actigraphy data. On average, the women spent 0.5 hours in MVPA, 6.2 hours in light PA, 10 hours in sedentary activities, and 5.3 hours sleeping within a 24-hour day. According to the isotemporal substitution models, replacing 30 minutes of sedentary behavior with MVPA reduced BMI by 1.4 kg/m2 and waist circumference by 4.0 cm. Replacing that same sedentary time with sleep reduced BMI by 0.5 kg/m2 and waist circumference by 1.4 cm. Replacing 30 minutes of light PA with MVPA decreased BMI by 1.6 kg/m2 and waist circumference by 4.3 cm. Replacing 30 minutes of light PA with sleep also reduced BMI by 0.8 kg/m2 and waist circumference by 1.7 cm. However, none of the behavioral substitutions affected blood pressure. Considering AAI women's short sleep duration, replacing their sedentary time with sleep might be a feasible strategy to reduce their BMI and waist circumference.

Isotemporal Substitution Modeling on Sedentary Behaviors and Physical Activity With Mortality Among People With Different Diabetes Statuses: A Prospective Cohort Study From the National Health and Nutrition Examination Survey Analysis 2007-2018.

To assess the associations of replacing sedentary behavior with different types of physical activity with mortality among the US adults of varying diabetes statuses. This prospective cohort study included 21,637 participants (mean age, 48.5y) from the National Health and Nutrition Examination Survey 2007-2018. Physical activity including leisure-time moderate-vigorous-intensity activity (MVPA), walking/bicycling, worktime MVPA, and sedentary behavior. We conducted an isotemporal substitution analysis using Cox regression to estimate the associations between replacements and mortality risks. We found significant protective associations between replacing 30minutes per day sedentary behavior with 3 types of physical activity and all-cause, cardiovascular disease (CVD) mortality risk (except worktime MVPA for CVD mortality) among total participants, with hazard ratio (HR; 95% confidence interval [CI]) ranging from 0.86 (0.77-0.95) to 0.96 (0.94-0.98). Among participants with diagnosed diabetes, replacing sedentary behavior with leisure-time MVPA was associated with a lower all-cause mortality risk (HR 0.81, 95% CI, 0.70-0.94), which was also observed in other subgroups, with HRs (95% CI) ranging from 0.87 (0.80-0.94) to 0.89 (0.81-0.99). Among those with prediabetes/undiagnosed diabetes, replacing sedentary behavior with walking/bicycling was associated with lower CVD mortality risk, and replacement to work-time MVPA was associated with lower all-cause and CVD mortality risk, with HRs (95% CI) ranging from 0.72 (0.63-0.83) to 0.96 (0.92-0.99). Replacing sedentary behaviors with 30minutes per day leisure-time MVPA was associated with lower all-cause mortality, regardless of diabetes statuses. Among people with prediabetes/undiagnosed diabetes, walking/bicycling was additionally associated with lower CVD mortality, and worktime MVPA was associated with lower all-cause and CVD mortality.

Cross-sectional associations between sedentary time with cognitive engagement and brain volume among community-dwelling vulnerable older adults.

Vulnerable older adults tend to decrease physical activity (PA) and increase sedentary time (ST). Previous research on the associations between ST and brain volume have yielded inconsistent findings, without considering the impact of cognitive engagement (CE) on cognitive function. We aimed to examine the association between ST with CE and brain volume. A structural magnetic resonance imaging survey was conducted among community-dwelling vulnerable older adults. Brain volumetric measurements were obtained using 3T magnetic resonance imaging and pre-processed using FreeSurfer. ST with low or high CE was assessed using a 12-item questionnaire. PA was assessed by the frequency of light and moderate levels of physical exercise according to the Japanese version of the Cardiovascular Health Study criteria. Participants were categorized into a low PA group and a moderate-to-high PA group. Among 91 participants (83.1 ± 5.2 years old, 61.5% female), 26 were low PA. The overall sample and moderate-to-high PA group did not show significant positive associations with brain volume for ST with high CE. In the low PA group, isotemporal substitution models showed that replacing ST with low CE by ST with high CE was significantly associated with increased brain volume in some areas, including the rostral and caudal anterior cingulate (β = 0.486-0.618, all P < 0.05, adjusted R2 = 0.344-0.663). Our findings suggest that replacing ST with low CE by ST with high CE is positively associated with brain volume in vulnerable older adults with low PA. Geriatr Gerontol Int 2024; 24: 82-89.

SEDENTARY BEHAVIOR DIFFERENTIALLY INFLUENCES COGNITIVE HEALTH IN OLDER ADULTS AT DIFFERENT TIMESCALES

Abstract The negative health effects of sedentary behavior have received increased attention over the past decade. Whether sedentary behavior negatively influences cognitive health at any timescale remains poorly understood. Our study sought to determine whether sedentary behavior negatively affects cognitive health throughout the adult lifespan at multiple timescales (acute within-day, day-to-day, cross-sectionally). We examined ambulatory assessment data generated by an adult lifespan sample (N=161; age range:19-88 years; 84% F) where cognition was repeatedly assessed via ultra-brief cognitive assessments of processing speed and working memory in an ecological momentary assessment (EMA) framework (6 assessments/day for 14 days). Activity was measured continuously via thigh-worn ActivPAL monitors. ActivPAL and EMA data were combined and modeled in a multi-level (3-level; moments within days within persons) isotemporal substitution modeling framework. Increased sedentary behavior was associated with acute decreases in processing speed for older participants (65+ years of age) and substitution modeling indicated that exchanging bouts of walking or standing for sedentary time would result in short-term improvements. In contrast, a consistent result across younger and older adults indicated that days with generally more sedentary time (as well as lying and standing) were associated with overall better processing speed and working memory capacity. No cross-sectional associations were observed. A lack of cross-sectional associations between sedentary behavior and cognitive performance was consistent with previous studies. Our current results extend previous findings by showing that sedentary behavior might influence cognitive performance differently at different timescales in younger and older adults.