Where Does the Time Go? Displacement of Device-Measured Sedentary Time in Effective Sedentary Behaviour Interventions: Systematic Review and Meta-Analysis

Associations of reallocating sedentary leisure-time to alternative discretionary movement behaviours with incident cardiometabolic diseases in 0.5 million Chinese adults

Background

In Chinese adults, there is a considerable burden of sedentary behaviour. This study aimed to estimate the implications of reallocating sedentary leisure-time to non-sedentary behaviours for incident cardiometabolic diseases.

Methods

A prospective cohort study of 462,370 Chinese adults (mean age 51 years; 59% female) who were free from diabetes and cardiovascular diseases at baseline. Isotemporal substitution Cox regression models were used to estimate the associations of reallocating self-reported sedentary leisure-time to the same amount of sleep, housework, Taichi, or conventional exercise (e.g., walking, jogging, ball games, swimming) with the risk of incident diabetes, stroke, and myocardial infarction (MI). The results are reported as adjusted hazard ratios and 95% confidence intervals per 30 min/day time exchanges. Potential impact fractions were calculated to estimate the proportional reductions in incident disease cases associated with time substitutions, assuming causality.

Findings

During >5.25 million person-years of follow-up, 19,738 incident diabetes, 51,460 stroke, and 6767 MI cases were accrued. Lower disease risks were found for replacement of sedentary leisure-time by sleep (diabetes: 0.97 [0.95-0.99], stroke: 0.98 [0.97-0.99], MI: 0.97 [0.94-0.99]; in participants who slept <7 h/day), housework (diabetes: 0.97 [0.97-0.98], stroke: 0.99 [0.98-0.99], MI: 0.97 [0.95-0.98]), Taichi (diabetes: 0.97 [0.95-0.99], stroke: 0.98 [0.97-0.99], MI: 0.95 [0.92-0.98]), or conventional exercise (diabetes: 0.97 [0.95-0.99], stroke: 0.97 [0.95-0.98], MI: 0.92 [0.88-0.96]). Potential impact fractions ranged from an estimated 3.5% (95% confidence interval: 3.1-3.9%) fewer cases of incident stroke when replacing sedentary leisure-time with housework, to an estimated 9.6% (5.9-13.3%) fewer cases of incident MI when reallocating sedentary leisure-time to conventional exercise.

Interpretation

Replacing sedentary leisure-time with behaviours such as housework, Taichi, sleep (in short sleepers) and conventional exercise is associated with lower risks of common cardiometabolic diseases in Chinese adults. Prevention strategies should be developed to promote movement behaviours and optimal levels of sleep at the expense of sedentary leisure-time.

Funding

This analysis was supported by a Health and Medical Research Fund (HMRF) Research Fellowship (grant no: 06200087).

Compositional associations between movement-related behaviours and functional outcomes post-stroke

PURPOSE

To examine the associations between the composition of movement-related behaviours (sedentary behaviour, sleep, standing, and stepping) and functional outcomes post-stroke.

METHODS

This study included 34 adults with stroke (mean age: 64.6 ± 12.5 years; time since stroke: 3.5 ± 1.1 months) who underwent an 8-week sedentary behaviour intervention. Functional outcomes were assessed using the timed up and go (TUG) and gait speed tests. Compositional data analysis was used to investigate the relationships between movement-related behaviours and functional outcomes.

RESULTS

The baseline composition of movement-related behaviours showed significant associations with changes in TUG (F = 4.28, p = 0.01) and gait speed (F = 4.63, p = 0.01) after the 8-week reducing sedentary behaviour intervention. Reallocating ≥ 30 min/day to stepping, while proportionally decreasing other movement-related behaviours, was associated with a significant change in TUG. Similarly, a relative reallocation of ≥ 40 min/day to stepping was associated with a clinically meaningful change in gait speed.

CONCLUSIONS

This study highlights the importance of considering movement-related behaviours in relation to functional outcomes post-stroke. Reallocating at least 30 min per day to stepping, relative to a reduction in other movement-related behaviours, is associated with significant and meaningful change in functional outcomes.

Delay Discounting and BMI in Hypertensives: Serial Mediations of Self-Efficacy, Physical Activity and Sedentary Behavior

Objective

Our study aimed to examine the association between delay discounting (DD) and body mass index (BMI) in individuals with hypertension. Additionally, we sought to explore and compare the potential mediating effects of self-efficacy, physical activity and sedentary behavior in this association.

Methods

A cross-sectional survey was conducted in two cities in the Jiangsu province of China, specifically Nanjing and Yangzhou, from March to June 2023. A total of 972 hypertensive patients completed the questionnaire (M age = 64.7 years, SD age = 8.2 years, 54.2% female). Participants engaged in a money choice experiment on computers, provided their height and weight, and completed the International Physical Activity Questionnaire-Short Form (IPAQ-SF) and General Self-Efficacy Scale (GSES). The experimental program was generated using the programming software E-Prime version 2.0. Multiple hierarchical regression analysis was conducted to identify potential covariates. Two serial mediation models were conducted using PROCESS macro 4.1 in SPSS 27.0. Physical activity and sedentary behavior were designated as M2 to investigate and contrast their respective mediating effects in the association between delay discounting and body mass index.

Results

Self-efficacy, physical activity, and sedentary behavior served as mediators in the relationship between delay discounting and BMI. Self-efficacy accounted for 14.9% and 14.3% of the total effect in Models 1 and 2, respectively, while physical activity and sedentary behavior each accounted for 14.9% and 9.5% of the total effect, respectively. The serial mediation effects of self-efficacy and physical activity, as well as self-efficacy and sedentary behavior, were significant (B = 0.01, 95% CI [0.01, 0.02]; B = 0.01, 95% CI [0.002, 0.01]), collectively contributing 2.1% and 2.4% of the total effect. Sedentary behavior played a smaller mediating role compared to physical activity in this association.

Conclusion

The results indicated that self-efficacy, physical activity and sedentary behavior could act as mediators in the association between delay discounting and BMI, thus potentially mitigating the risk of obesity in hypertensive individuals.

The Effect of Sedentary Behaviour on Cardiorespiratory Fitness: A Systematic Review and Meta-Analysis

BACKGROUND

Cardiorespiratory fitness (CRF) is an important indicator of current and future health. While the impact of habitual physical activity on CRF is well established, the role of sedentary behaviour (SB) remains less understood.

OBJECTIVE

We aimed to determine the effect of SB on CRF.

METHODS

Searches were conducted in MEDLINE, Embase, PsycINFO, CINAHL and SPORTDiscus from inception to August 2022. Randomised controlled trials, quasi-experimental studies and cohort studies that assessed the relationship between SB and CRF were eligible. Narrative syntheses and meta-analyses summarised the evidence, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) certainty was based on evidence from randomised controlled trials.

RESULTS

This review included 18 studies that focused on youth (four randomised controlled trials, three quasi-experimental studies, 11 cohort studies) and 24 on adult populations (15 randomised controlled trials, five quasi-experimental studies, four cohort studies). In youth and adults, evidence from randomised controlled trials suggests mixed effects of SB on CRF, but with the potential for interventions to improve CRF. Quasi-experimental and cohort studies also support similar conclusions. Certainty of evidence was very low for both age groups. A meta-analysis of adult randomised controlled trials found that interventions targeting reducing SB, or increasing physical activity and reducing SB, had a significant effect on post-peak oxygen consumption (mean difference = 3.16 mL.kg-1.min-1, 95% confidence interval: 1.76, 4.57).

CONCLUSIONS

Evidence from randomised controlled trials indicates mixed associations between SB and CRF, with the potential for SB to influence CRF, as supported by meta-analytical findings. Further well-designed trials are warranted to confirm the relationship between SB and CRF, explore the effects of SB independent from higher intensity activity, and investigate the existence of such relationships in paediatric populations.

CLINICAL TRIAL REGISTRATION

PROSPERO CRD42022356218.

Substituting device-measured sedentary time with alternative 24-hour movement behaviours: compositional associations with adiposity and cardiometabolic risk in the ORISCAV-LUX 2 study

BACKGROUND

There is a considerable burden of sedentary time in European adults. We aimed to quantify the differences in adiposity and cardiometabolic health associated with theoretically exchanging sedentary time for alternative 24 h movement behaviours.

METHODS

This observational cross-sectional study included Luxembourg residents aged 18-79 years who each provided  ≥ 4 valid days of triaxial accelerometry (n = 1046). Covariable adjusted compositional isotemporal substitution models were used to examine if statistically replacing device-measured sedentary time with more time in the sleep period, light physical activity (PA), or moderate-to-vigorous PA (MVPA) was associated with adiposity and cardiometabolic health markers. We further investigated the cardiometabolic properties of replacing sedentary time which was accumulated in prolonged (≥ 30 min) with non-prolonged (< 30 min) bouts.

RESULTS

Replacing sedentary time with MVPA was favourably associated with adiposity, high-density lipoprotein cholesterol, fasting glucose, insulin, and clustered cardiometabolic risk. Substituting sedentary time with light PA was associated with lower total body fat, fasting insulin, and was the only time-exchange to predict lower triglycerides and a lower apolipoprotein B/A1 ratio. Exchanging sedentary time with more time in the sleep period was associated with lower fasting insulin, and with lower adiposity in short sleepers. There was no significant evidence that replacing prolonged with non-prolonged sedentary time was related to outcomes.

CONCLUSIONS

Artificial time-use substitutions indicate that replacing sedentary time with MVPA is beneficially associated with the widest range of cardiometabolic risk factors. Light PA confers some additional and unique metabolic benefit. Extending sleep, by substituting sedentary time with more time in the sleep period, may lower obesity risk in short sleepers.