Associations of sedentary behavior bouts with community-dwelling older adults' physical function

Associations between accelerometer-measured physical activity and sedentary behaviour with physical function among older women: a cross-sectional study

BACKGROUND

This study aimed to investigate the relationships between accelerometer-measured physical activity (PA) and sedentary behaviour (SB) with physical function (PF) among older Chinese women in the community.

METHODS

The present study comprised 1,113 community-dwelling older females, with an average age of 65 ± 2 years. We employed a linear regression analysis to investigate the relationship between patterns of PA and SB with PF. PA variables consisted of total PA time, bouted PA time (a continuous PA that lasts equal to or more than 10 min), and sporadic PA time (a continuous PA that lasts less than 10 min). SB variables included total SB time, 30-min bout of SB (a continuous SB that lasts equal to or more than 30 min), and 60-min bout of SB (a continuous SB that lasts equal to or more than 60 min). PF variables comprised handgrip strength (HGS), one-legged stance test with eyes closed (OLSTEC), usual walking speed (UWS), maximum walking speed (MWS) and chair-stand time (CT). To explore the joint effects of moderate-to-vigorous-intensity PA (MVPA) and SB on PF, we divided the duration of SB and MVPA participation in older women into different combinations: low MVPA & high SB, low MVPA & low SB, high MVPA & high SB, high MVPA & low SB.

RESULTS

The study revealed a significant association between 30-min bout of SB and CT, which remained after adjusting for total MVPA time (P = 0.021). Both total MVPA and bouted MVPA were found to be positively associated with better UWS, MWS, CT, and PF Z-score. When the combination of low MVPA & high SB was used as a reference, the regression coefficients for PF ascended by 1.32 (P < 0.001) in the high MVPA & high SB group and by 1.13 (P < 0.001) in the high MVPA & low SB group.

CONCLUSIONS

A significant association was observed between poorer lower limb function and prolonged, uninterrupted SB in older women, rather than with the total SB time. Concurrently, the insufficient engagement in MVPA may also be a crucial factor contributing to poorer PF in older women. Engaging in longer durations and higher intensity of PA, such as bouts of MVPA lasting a minimum of 10 min or longer, may contribute to better PF.

Determinants of sedentary behavior in community-dwelling older adults with type 2 diabetes based on the behavioral change wheel: a path analysis

BACKGROUND

Sedentary behavior (SB) is deeply ingrained in the daily lives of community-dwelling older adults with type 2 diabetes mellitus (T2DM). However, the specific underlying mechanisms of the determinants associated with SB remain elusive. We aimed to explore the determinants of SB based on the behavior change wheel framework as well as a literature review.

METHODS

This cross-sectional study recruited 489 community-dwelling older adults with T2DM in Jinan City, Shandong Province, China. Convenience sampling was used to select participants from relevant communities. This study used the Measure of Older Adults' Sedentary Time-T2DM, the Abbreviated-Neighborhood Environment Walkability Scale, the Social Support Rating Scale, the Lubben Social Network Scale 6, the Subjective Social Norms Questionnaire for Sedentary Behavior, the Functional Activities Questionnaire, the Numerical Rating Scale, the Short Physical Performance Battery, and the Montreal Cognitive Assessment Text to assess the levels of and the determinants of SB. Descriptive statistical analysis and path analysis were conducted to analyze and interpret the data.

RESULTS

Pain, cognitive function, social isolation, and social support had direct and indirect effects on SB in community-dwelling older adults with T2DM (total effects: β = 0.426, β = -0.171, β = -0.209, and β = -0.128, respectively), and physical function, walking environment, and social function had direct effects on patients' SB (total effects: β = -0.180, β = -0.163, and β = 0.127, respectively). All the above pathways were statistically significant (P < 0.05). The path analysis showed that the model had acceptable fit indices: RMSEA = 0.014, χ 2/df = 1.100, GFI = 0.999, AGFI = 0.980, NFI = 0.997, RFI = 0.954, IFI = 1.000, TLI = 0.996, CFI = 1.000.

CONCLUSION

Capability (physical function, pain, and cognitive function), opportunity (social isolation, walking environment, and social support), and motivation (social function) were effective predictors of SB in community-dwelling older adults with T2DM. Deeper knowledge regarding these associations may help healthcare providers design targeted intervention strategies to decrease levels of SB in this specific population.

Cross-sectional interactive associations of physical activity and sedentary behaviour with physical capacity across adulthood

BACKGROUND

The way physical activity (PA) and sedentary behaviour (SB) independently and interactively modify the age-related decline in physical capacity remains poorly understood. This cross-sectional study investigated the independent and interactive associations of PA and SB with physical function and performance throughout the adult life course.

METHODS

Data from 499 community-dwelling adults (63% female) aged 20-92 years, involved in the INSPIRE Human Translational Cohort, were used in this cross-sectional study. Daily time spent on moderate-to-vigorous PA (MVPA, min/day) and SB (h/day) was measured with activPAL triaxial accelerometers. Physical function and performance were assessed through the measurement of the 4-m usual gait speed (m/s), handgrip strength (kg), lower-limb strength (isokinetic knee extension torque, N·m), estimated lower-limb power (five-time chair-rise test performance, s) and cardiorespiratory fitness (V̇O2max, mL/kg/min). Confounder-adjusted multiple linear and curvilinear regressions were performed to investigate how MVPA, SB and their interactions were associated with the physical outcomes (all square root-transformed except gait speed) throughout the adulthood spectrum.

RESULTS

Interaction analyses revealed that the combination of higher levels of MVPA with lower levels of SB favourably reshaped the negative relationship between handgrip strength and age (age2 × SB × MVPA: B = -7E-08, SE = 3E-08, P < 0.05). In addition, higher levels of MVPA were independently associated with an improved age-related profile in gait speed (age2 × MVPA: B = 3E-06, SE = 1E-06, P < 0.05), chair-rise performance (age × MVPA: B = -9E-05, SE = 4E-05, P < 0.05) and V̇O2max (MVPA at 21 years: B = 3E-02, SE = 7E-03, P < 0.05; age × MVPA: B = -5E-04, SE = 2E-04, P < 0.05). Conversely, the detrimental association of age with lower-limb muscle strength (age × SB: B = -1E-04, SE = 6E-05, P < 0.05) and chair-rise performance (age × SB: B = 1E-05, SE = 7E-06, P < 0.05) was exacerbated with increasing duration of SB, independently of MVPA. Supplementary analyses further revealed that some of these associations were age and sex specific.

CONCLUSIONS

This cross-sectional study demonstrated that reduced sedentary time and increased activity duration were independently and synergistically associated with an attenuated age-related loss in physical capacity. These findings need to be confirmed with longitudinal data but encourage both adopting an active lifestyle and reducing sedentary time as preventive measures against physical aging.

Association of 'Tortoise' and 'Hare' movement behavior patterns with cardiometabolic health, body composition, and functional fitness in older adults

We investigated the association of movement behavior patterns with cardiometabolic health, body composition, and functional fitness in older adults. A total of 242 older adults participated of this cross-sectional study. Sedentary time, light physical activity (LPA) and moderate-vigorous physical activity (MVPA), steps/day, and step cadence were assessed by accelerometry. The movement behavior patterns were derived by principal component analysis. Cardiometabolic health was defined by a metabolic syndrome score (cMetS). Body composition was determined by appendicular lean mass/body mass index (ALM/BMI). Functional fitness was assessed by a composite z-score from the Senior Fitness Test battery. Two patterns were identified: 'Tortoise' (low sedentary time, high LPA and steps/day) and 'Hare' (high MVPA, steps/day, and step cadence). 'Tortoise' and 'Hare' were associated with better cMetS. 'Hare' was positively associated with ALM/BMI and Functional Fitness. While 'Tortoise' and 'Hare' were associated with better cMetS, only 'Hare' was associated with better ALM/BMI and functional fitness.

Participation in youth sports influences sarcopenia parameters in older adults

Background

The degree of deterioration in sarcopenia parameters may be affected by a person's level of physical activity (PA) and sedentary behavior (SB). Our study focused on examining the PA and SB of active older adults including those with and without history of sports in youth.

Methods

Forty-four participants (20 men and 24 women, mean age of total sample 76.1 ± 5.2 years) were included in analysis of PA, SB habits and sarcopenia parameters, determined by skeletal muscle index, hand-grip strength, gait speed, Timed Up and Go tests (TUG). PA and SB were recorded with accelerometers. Our primary aim was to compare participants with (AH) or without a sport history in youth (NAH), in their sarcopenia parameters and PA and SB habits.

Results

When divided participants in two groups (AH and NAH) and adjusting for age, we have detected the differences for skeletal muscle index (p = 0.007) and hand-grip strength (p = 0.004) in favor of participants who were engaged in sports in youth. We did not find any differences in PA and SB habits between the AH and NAH groups. After adjusting for age, participants with a higher number of daily steps, longer moderate to vigorous physical activity (MVPA) bouts, a higher number of MVPA bouts in a day and higher overall MVPA engagement achieved better results in hand-grip strength and TUG. Participants with lower SB had better TUG and gait speed results.

Conclusions

Our findings suggest that engaging in sports activities in youth can make a difference with sarcopenia parameters. Although we found no differences in PA and SB habits between participants with AH and NAH, participants with an athlete history performed better results in sarcopenia parameters.

Prolonged bouts of sedentary behavior in people with chronic obstructive pulmonary disease and associated factors

BACKGROUND

Increased sedentary behavior (SB), especially in prolonged bouts, is associated with adverse health outcomes, but little is known about patterns of SB in people with chronic obstructive pulmonary disease (COPD).

OBJECTIVES

The purpose of this study was to describe SB and patterns of SB and to examine factors associated with prolonged bouts of SB in inactive community-dwelling adults with COPD.

METHODS

This cross-sectional analysis used data from inactive adults with COPD who were enrolled in an exercise program but had not started exercising. Participants were ≥ 50 years old with a diagnosis of COPD, had a forced expiratory volume in one second < 80% predicted, and were inactive. Participants wore an activPAL device for seven days to measure their SB and completed surveys and physical measures. Data were analyzed with multiple regression.

RESULTS

The sample included 160 participants with a mean age (± SD) of 69 ± 8, and a mean total sedentary time of 742 ± 150 min/day, with 254 ± 146 min/day in SB bouts ≥ 60 min.

DURATION

Time spent in bouts of SB ≥ 60-min. was negatively associated with self-efficacy for overcoming barriers to light physical activity (P<0.05), balance (P<0.05), chair stand test (P<0.05), FEV1% predicted (P<0.05) and positively associated with BMI (P<0.001).

CONCLUSIONS

Inactive people with COPD engage in extensive SB, much of it in prolonged bouts. Self-efficacy, balance, and lower body strength are modifiable variables associated with SB and potential targets for future interventions to reduce time in prolonged sedentary behavior.

Physical activity measurements in individuals with interstitial lung disease: a systematic review and meta-analysis

BACKGROUND

Physical activity (PA) measurements are becoming common in interstitial lung disease (ILD); however, standardisation has not been achieved. We aimed to systematically review PA measurement methods, present PA levels and provide practical recommendations on PA measurement in ILD.

METHODS

We searched four databases up to November 2022 for studies assessing PA in ILD. We collected information about the studies and participants, the methods used to measure PA, and the PA metrics. Studies were scored using 12 items regarding PA measurements to evaluate the reporting quality of activity monitor use.

RESULTS

In 40 of the included studies, PA was measured using various devices or questionnaires with numerous metrics. Of the 33 studies that utilised activity monitors, a median of five out of 12 items were not reported, with the definition of nonwear time being the most frequently omitted. The meta-analyses showed that the pooled means (95% CI) of steps, time spent in moderate to vigorous PA, total energy expenditure and sedentary time were 5215 (4640-5791) steps·day^-1, 82 (58-106) min·day^-1, 2130 (1847-2412) kcal·day^-1 and 605 (323-887) min·day^-1, respectively, with considerable heterogeneity.

CONCLUSION

The use of activity monitors and questionnaires in ILD lacks consistency. Improvement is required in the reporting quality of PA measurement methods using activity monitors.

Accelerometer-measured sedentary behavior and risk of functional disability in older Japanese adults: a 9-year prospective cohort study

BACKGROUND

The associations of sedentary time and patterns with functional disability among older adults remain unclear, and few studies have accounted for the co-dependency of sedentary behavior and physical activities when modeling sedentary behavior with risk of functional disability. We aimed to examine the associations between sedentary time and patterns and risk of incident functional disability, and assess whether replacing sedentary time with light physical activity (LPA) or moderate-to-vigorous intensity physical activity (MVPA) is associated with reduced risk of functional disability in community-dwelling older adults.

METHODS

A total of 1,687 Japanese adults aged ≥ 65 years without functional disability at baseline were prospectively followed-up for 9 years (2011-2020). Functional disability was ascertained using the national database of Japan's Long-term Care Insurance System. Sedentary time and patterns, LPA, and MVPA were measured using a tri-axial accelerometer secured to participants' waists.

RESULTS

During follow-up, 466 participants developed functional disability. Compared with the lowest quartile of total sedentary time, the multivariable-adjusted hazard ratios (95% confidence intervals) of functional disability for the second, third, and top quartiles were 1.21 (0.91‒1.62), 1.45 (1.10‒1.92), and 1.40 (1.05‒1.88) (p for trend = 0.01). After further adjusting for MVPA, total sedentary time was no longer significantly associated with the risk of functional disability (p for trend = 0.41). Replacing 10 min/day of sedentary time with the same amount of MVPA (but not LPA) was significantly associated with a 12% reduced risk of functional disability (hazard ratio [95% confidence interval]: 0.88 [0.84‒0.92]). No significant association was observed between sedentary bout length and functional disability.

CONCLUSION

Higher levels of total sedentary time were associated with an increased risk of incident functional disability. However, this association was not independent of MVPA. Replacing sedentary time with MVPA, but not LPA, was associated with reduced risk of functional disability in older adults.

Leisure Sedentary Time is Associated with Self-Reported Falls in Middle-aged and Older Females and Males: an Analysis of the CLSA

Aim

The purpose of this analysis was to report the prevalence of falls and falls-related injuries among those reporting different volumes of weekly sedentary time, and to understand the association of sedentary time and falls, accounting for functional fitness.

Methods

Baseline and first follow-up data from the Canadian Longitudinal Study on Aging (CSLA) were analyzed (n=22,942). Participants self-reported whether they had a fall in the past 12 months (at baseline) and whether they had an injury that was a result of a fall (follow-up). In-home interviews collected self-reported leisure sedentary time using the Physical Activity Scale for Elderly. Functional fitness was assessed using grip strength, timed-up-and-go, and chair rise tests during clinic visits.

Results

The prevalence of falls was higher among those who reported higher sedentary time. For example, among males aged 65 and older who reported lower sedentary time (<1,080 min/week), the prevalence of falls in the past 12 months (at baseline) was 7.8% compared to 9.8% in those reporting higher sedentary time. The odds of reporting a fall (at baseline) was 21% higher in those who reported higher sedentary time (OR: 1.21; 95%CI: 1.11-1.33) in adjusted models. No associations were found between sedentary time and injuries due to a fall.

Conclusions

Reporting high volumes of sedentary time may increase the risk of falls. Future research using device-based estimates of total sedentary time and breaks in sedentary time is needed to further elucidate this association.

Diurnal pattern of breaks in sedentary time and the physical function of older adults

BACKGROUND

The association of breaks in sedentary time with outcomes of physical function can vary according to the time of day. We examined the association of the diurnal pattern of breaks in sedentary time with physical function outcomes in older adults.

METHODS

A cross-sectional analysis was conducted among 115 older adults (≥60 years). The overall and time-specific breaks (morning: 06:00-12:00; afternoon: 12:00-18:00; evening: 18:00-24:00) in sedentary time were assessed using a triaxial accelerometer (Actigraph GT3X+). A break in sedentary time was defined as at least 1 min where the accelerometer registered ≥100 cpm following a sedentary period. Five physical function outcomes were assessed: handgrip strength (dynamometer), balance ability (single leg stance), gait speed (11-m walking), basic functional mobility (time up and go), and lower-limb strength (five times sit-to-stand). Generalized linear models were used to examine the associations of the overall and time-specific breaks in sedentary time with the physical function outcomes.

RESULTS

Participants showed an average of 69.4 breaks in sedentary time during the day. Less frequent breaks in the evening (19.3) were found than that in the morning (24.3) and the afternoon (25.3) (p < 0.05). Breaks in sedentary time during the day were associated with less time on gait speed in older adults (exp (β) = 0.92, 95% confidence interval [CI] 0.86-0.98; p < 0.01). Time-specific analysis showed that breaks in sedentary time were associated with less time on gait speed (exp (β) = 0.94, 95% CI 0.91-0.97; p < 0.01), basic functional mobility (exp (β) = 0.93, 95% CI 0.89-0.97; p < 0.01), and lower-limb strength (exp (β) = 0.92, 95% CI 0.87-0.97; p < 0.01) in the evening only.

CONCLUSION

A break in sedentary time, particularly during the evening, was associated with better lower extremity strength in older adults. Further strategies to interrupt sedentary time with frequent breaks, with an emphasis on evening hours, can be helpful to maintain and improve physical function in older adults.

Influence of 2 Digital Exercise Modules of a Multimodular System on Balance and Leg Strength Under Consideration of Use Adherence: Prospective Cohort Study

Background

To empower healthy aging, digital solutions embed multiple modules for physical activity, cognitive health promotion, and social engagement. Integrating new empowering technologies such as digital exercise monitoring requires assessment measures and analysis procedures, considering variable compliance of users with different modules.

Objective

This study aims to assess the influence of a tablet-based and a feedback system–based exercise module on balance and leg strength by considering use adherence instead of the use of the entire multimodular system.

Methods

In the prospective cohort study within the fit4AAL project, 83 users (n=67, 81% women; n=16, 19% men; mean age 66.2, SD 2.3 years) used the 2 digital exercise modules of a multimodular physical activity promotion system for >18 weeks. A data-driven clustering method based on the average use frequency of the exercise modules determined the number of user types that met the World Health Organization–recommended training frequency of at least twice per week. On the basis of this use adherence, statistical analysis was performed with features of functional performance tests (unipedal stance, 30-second chair rise, Y-balance, and hurdle step tests). The tests were conducted 6 months before the intervention, immediately before the intervention, and after the intervention, comparing the baseline phase with the 3 feedback use groups of the study (using only the tablet, the tablet and the feedback system, or only the feedback system).

Results

Of the 83 users, 43 (52%) met the World Health Organization–recommended frequency of muscle-strengthening activities. Overall, the feedback use groups achieved, on average, more chair rises in 30 seconds than the baseline group (P=.01; moderate effect size of 0.07). Of the 43 users, 26 (60%) additionally used the feedback system–based exercise module. They improved in balance compared with the users using either the tablet or the feedback system (P=.02). In addition, they improved their leg strength within the group (P=.04) and compared with the baseline (P=.01).

Conclusions

The additional use of a feedback system showed a tendency to positively maintain and influence the already exceptionally high functional performance of older adults. Considering use adherence in future multimodular system studies is crucial to assess the influence of single and combined use of exercise modules on functional performance.

Sleep Should Be Focused on When Analyzing Physical Activity in Hospitalized Older Adults after Trunk and Lower Extremity Fractures-A Pilot Study

Although the importance of resting in bed for hospitalized older adults is known, current methods of interpreting physical activity (PA) recommend the use of a broad definition of sedentary behavior (SB) that includes 0−1.5 metabolic equivalents (METs) of sleep (SL) and sitting. We investigated the characteristics of PA by conducting a cross-sectional study of 25 older adults with trunk and lower extremity fractures. The intensity of their PA was interpreted as SL (0−0.9 METs), SB (1−1.5 METs), low-intensity PA (LIPA: 1.6−2.9 METs), and moderate-to-vigorous PA (MVPA: >3.0 METs). We calculated the correlation coefficients to clarify the relationship between each PA intensity level. Our analyses revealed that the PA time (min/day) was accounted for by SB (53.5%), SL (23.2%), LIPA (22.8%), and MVPA (0.5%). We observed negative correlations between SL and SB (r  =  −0.837) and between SL and LIPA (r  =  −0.705), and positive correlations between SB and LIPA (r  =  0.346) and between LIPA and MVPA (r  =  0.429). SL and SB were also found to have different trends in relation to physical function. These results indicate that SL and SB are trade-offs for PA during the day. Separate interpretations of the SL and SB of older hospitalized adults are thus recommended.

Associations of device-measured sleep, sedentariness and physical activity with growth differentiation factor 15 in older adults

BACKGROUND

Growth differentiation factor 15 (GDF-15) is a biomarker for chronic disease burden that might explain the health effects of sedentary behaviours (SBs) and physical activity (PA). We examined associations of device-measured sleep, SB and PA, and time reallocations among them, with GDF-15 in older adults.

METHODS

We used data from 2245 older adults participating in the Seniors-ENRICA-2 study. Wrist-worn accelerometers were employed to ascertain total time in sleep, SB, light PA (LPA) and moderate-to vigorous PA (MVPA). Associations between these activities and serum GDF-15 levels were analysed using linear regression, including isotemporal substitution models for time reallocations among activities, and adjusted for potential confounders. Analyses were conducted separately in two groups (less active and more active individuals) according to the median total PA time.

RESULTS

In the less active participants, 30 min/day more of MVPA were related to lower levels of GDF-15 when replacing sleep (fully adjusted mean percentage differences [95% confidence interval] in GDF-15 of -9.2% [-13.2, -5.0]), SB (-9.8% [-13.6, -5.8]) and LPA (-5.8% [-11.1, -0.3]), whereas 30 min/day more of LPA were related to lower GDF-15 when replacing both sleep (-3.6% [-6.1, -1.0]) and SB (-4.2% [-6.7, -1.7]). In the more active participants, 30 min/day more of MVPA were also associated with lower GDF-15 when replacing sleep (-2.9% [-5.3, -0.3]), SB (-2.4% [-4.6, -0.2]) and LPA (-3.5% [-6.6, -0.3]), but no associations were found for more time in LPA. Spending more time in SB was associated with higher GDF-15 levels only among those less active (1.9% [0.9, 2.9] per 30 min/day increment). Sleep time did not appear to be associated with GDF-15.

CONCLUSIONS

The MVPA was inversely associated with GDF-15, with stronger associations at lower PA volumes. Also, more LPA and less SB time were linked to lower GDF-15 in the less active individuals. This suggests that simply moving more and sitting less may reduce chronic disease burden in older adults.

Associations of Objectively-Measured Sedentary Time and Patterns with Cognitive Function in Non-Demented Japanese Older Adults: A Cross-Sectional Study

This study aimed to investigate the cross-sectional associations of objectively-measured sedentary time and patterns with cognitive function in Japanese older adults. A total of 1681 non-demented community-dwelling older adults (aged 73 ± 6, 62.1% women) were included. Total sedentary time, prolonged sedentary time (accumulated in ≥30 min bouts) and mean sedentary bout length were assessed using a tri-axial accelerometer. Global and domain-specific cognitive functions were measured using the Montreal Cognitive Assessment. The average of total sedentary time and prolonged sedentary time were 462 ± 125 and 186 ± 111 min/day, respectively. Greater prolonged sedentary time, but not total sedentary time, was significantly associated with poorer performance in the orientation domain even after controlling for moderate-to-vigorous physical activity (p for trend = 0.002). A significant inverse association was also observed between mean sedentary bout length and the orientation domain (p for trend = 0.009). No significant associations were observed for global cognitive function or other cognitive domains. Sedentary time accumulated in prolonged bouts, but not total sedentary time, was inversely associated with orientation ability among older adults. Our results encourage further researches to confirm the role of prolonged sedentary time in changes to cognitive domains over time among older adults.

Learning From Human Responses to Deconditioning Environments: Improved Understanding of the "Use It or Lose It" Principle

Physical activity, mobility or patterned mobility (i.e., exercise) is intrinsic to the functioning of Homo sapiens, and required for maintenance of health. Thus, systems such as the musculoskeletal and cardiovascular systems appear to require constant reinforcement or conditioning to maintain integrity. Loss of conditioning or development of chronic deconditioning can have multiple consequences. The study of different types of deconditioning and their prevention or reversal can offer a number of clues to the regulation of these systems and point to how deconditioning poses risk for disease development and progression. From the study of deconditioning associated with spaceflight, a condition not predicted by evolution, prolonged bedrest, protracted sedentary behavior, as well as menopause and obesity and their consequences, provide a background to better understand human heterogeneity and how physical fitness may impact the risks for chronic conditions subsequent to the deconditioning. The effectiveness of optimized physical activity and exercise protocols likely depend on the nature of the deconditioning, the sex and genetics of the individual, whether one is addressing prevention of deconditioning-associated disease or disease-associated progression, and whether it is focused on acute or chronic deconditioning associated with different forms of deconditioning. While considerable research effort has gone into preventing deconditioning, the study of the process of deconditioning and its endpoints can provide clues to the regulation of the affected systems and their contributions to human heterogeneity that have been framed by the boundary conditions of Earth during evolution and the "use it or lose it" principle of regulation. Such information regarding heterogeneity that is elaborated by the study of deconditioning environments could enhance the effectiveness of individualized interventions to prevent deconditions or rescue those who have become deconditioned.

Identifying conducive contexts and working mechanisms of sedentary behaviour interventions in older adults: a realist review protocol as part of the 'Stand UP Seniors' project

INTRODUCTION

Lifestyle behaviours, including sedentary behaviour, have been listed as key modifiable factors to promote healthy ageing. Sedentary behaviour is ubiquitous in older adults and has a strong link with age-related functional declines and chronic health conditions. Although several interventions have been developed aimed at the reduction of sedentary behaviour in older adults, little in-depth information is available on how these complex interventions work in different contexts. Therefore, the aim of our study was to unpack the mechanisms of how existing interventions aimed at the reduction of older adults' sedentary behaviour work or fail to work in particular contexts in order to optimise the development and implementation of future sedentary behaviour interventions.

METHODS AND ANALYSIS

A realist review will be conducted as a first part of the Stand UP Seniors (SUPS) project and will be structured as follows: (1) defining the scope of the review, (2) searching and appraising the evidence, (3) extracting data and synthesising the results, and (4) drawing conclusions and formulating recommendations. The result of this iterative process will be a final programme theory that can be used to identify which context triggers which mechanism, and in turn might elicit which outcome. The final programme theory will be used to inform the second and the third parts of the SUPS project, which are, respectively, the development and evaluation of a sedentary behaviour intervention in older adults.

ETHICS AND DISSEMINATION

Ethical approval is not required for the review. Dissemination of the realist review results, including the final programme theory, will occur through peer-reviewed publications and presentations at relevant conferences. The peer-reviewed realist review will be prepared according to the Realist and Meta-narrative Evidence Synthesis: Evolving Standards publication standards for realist syntheses.

PROSPERO REGISTRATION NUMBER

CRD42021248795.