The energy expenditure of sedentary behavior: a whole room calorimeter study

Physiology of sedentary behavior

Sedentary behaviors (SB) are characterized by low energy expenditure while in a sitting or reclining posture. Evidence relevant to understanding the physiology of SB can be derived from studies employing several experimental models: bed rest, immobilization, reduced step count, and reducing/interrupting prolonged SB. We examine the relevant physiological evidence relating to body weight and energy balance, intermediary metabolism, cardiovascular and respiratory systems, the musculoskeletal system, the central nervous system, and immunity and inflammatory responses. Excessive and prolonged SB can lead to insulin resistance, vascular dysfunction, shift in substrate use toward carbohydrate oxidation, shift in muscle fiber from oxidative to glycolytic type, reduced cardiorespiratory fitness, loss of muscle mass and strength and bone mass, and increased total body fat mass and visceral fat depot, blood lipid concentrations, and inflammation. Despite marked differences across individual studies, longer term interventions aimed at reducing/interrupting SB have resulted in small, albeit marginally clinically meaningful, benefits on body weight, waist circumference, percent body fat, fasting glucose, insulin, HbA1c and HDL concentrations, systolic blood pressure, and vascular function in adults and older adults. There is more limited evidence for other health-related outcomes and physiological systems and for children and adolescents. Future research should focus on the investigation of molecular and cellular mechanisms underpinning adaptations to increasing and reducing/interrupting SB and the necessary changes in SB and physical activity to impact physiological systems and overall health in diverse population groups.

The association between sleep duration and detailed measures of obesity: A cross sectional analysis in the ADDITION-PRO study

Background

Sleep duration is associated with BMI and waist circumference. However, less is known about whether sleep duration affects different measurements of obesity differently.

Objective

To investigate the association between sleep duration and different measures of obesity.

Methods

In this cross-sectional analysis 1309, Danish, older adults (55% men) completed at least 3 days of wearing a combined accelerometer and heart rate-monitor for assessing sleep duration (hours/night) within self-reported usual bedtime. Participants underwent anthropometry and ultrasonography to assess BMI, waist circumference, visceral fat, subcutaneous fat, and fat percentage. Linear regression analyses examined the associations between sleep duration and obesity-related outcomes.

Results

Sleep duration was inversely associated with all obesity-related outcomes, except visceral-/subcutaneous-fat-ratio. After multivariate adjustment the magnitude of associations became stronger and statistically significant for all outcomes except visceral-/subcutaneous-fat-ratio, and subcutaneous fat in women. The associations with BMI and waist circumference demonstrated the strongest associations, when comparing standardized regression coefficients.

Conclusions

Shorter sleep duration were associated with higher obesity across all outcomes except visceral-/subcutaneous-fat-ratio. No specifically salient associations with local or central obesity were observed. Results suggest that poor sleep duration and obesity correlate, however, further research is needed to conclude on beneficial effects of sleep duration regarding health and weight loss.

A potent physiological method to magnify and sustain soleus oxidative metabolism improves glucose and lipid regulation

Slow oxidative muscle, most notably the soleus, is inherently well equipped with the molecular machinery for regulating blood-borne substrates. However, the entire human musculature accounts for only ∼15% of the body’s oxidative metabolism of glucose at the resting energy expenditure, despite being the body’s largest lean tissue mass. We found the human soleus muscle could raise local oxidative metabolism to high levels for hours without fatigue, during a type of soleus-dominant activity while sitting, even in unfit volunteers. Muscle biopsies revealed there was minimal glycogen use. Magnifying the otherwise negligible local energy expenditure with isolated contractions improved systemic VLDL-triglyceride and glucose homeostasis by a large magnitude, e.g., 52% less postprandial glucose excursion (∼50 mg/dL less between ∼1 and 2 h) with 60% less hyperinsulinemia. Targeting a small oxidative muscle mass (∼1% body mass) with local contractile activity is a potent method for improving systemic metabolic regulation while prolonging the benefits of oxidative metabolism.

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We developed a method to capitalize upon the unique phenotype of the soleus

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“A high quality versus large quantity perspective” for muscle activation

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Singular movement targeting the 1 kg soleus easily sustains oxidative metabolism

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This method provides a distinct muscular activity stimulus for metabolic control

Genetic susceptibility, screen-based sedentary activities and incidence of coronary heart disease

BACKGROUND

Whether the associations of time spent in screen-based sedentary activities with CHD vary by genetic susceptibility is currently unknown. The objective of this study was to examine the interplay of genetic susceptibility to CHD and two prevalent types of screen-based sedentary activities (television [TV] viewing and computer use) for CHD incidence.

METHODS

This prospective cohort study included 373,026 individuals of European ancestry without prevalent CHD/stroke from UK Biobank data. Genetic susceptibility to CHD was assessed using weighted polygenic risk scores, calculated by summing the number of risk-increasing alleles among 300 single-nucleotide polymorphisms, multiplied by their corresponding effect estimates. TV viewing and computer use were assessed through touch-screen questionnaires. CHD incidence (n=9185) was adjudicated over a median 12.6-year follow-up.

RESULTS

Compared with ≥4h/day of TV viewing, the hazard ratio of CHD was 0.84 (95% confidence interval [CI] 0.79-0.90) and 0.94 (0.90-0.99) for ≤1h/day and 2-3h/day of TV viewing, respectively, after adjusting for confounders including the genetic risk. CHD hazards were higher for medium and high genetic risk than for low genetic risk. Across all levels of genetic risk including high-genetic risk, ≤1h/day of TV viewing had lower CHD hazards, compared with ≥4h/day: no evidence of interaction between genetic risk and TV viewing (p value: 0.362). Estimates of the population attributable fraction (PAF) suggested that 10.9% (95% CI 6.1-15.3%) of CHD could be prevented if TV viewing time were reduced to ≤1h/day, assuming causality. The PAF values were relatively larger for medium-to-high genetic risk than for low genetic risk, although the CIs were wide and overlapping. No associations were observed for computer use.

CONCLUSIONS

Less TV viewing time was associated with lower CHD risk independently of genetic risk. Clinical trials targeted at individuals with high genetic susceptibility should consider reducing TV viewing as as a behavioural target for prevention of an early onset of cardiovascular events.

Sedentary behaviour levels in adults with an intellectual disability: a systematic review and meta-analysis

Background: Sedentary behaviour (SB), which is characterised by low levels of energy expenditure, has been linked to increased cardio-metabolic risks, obesity and mortality, as well as cancer risk. No firm guidelines are established on safe levels of SB. Adults with an intellectual disability (ID) have poorer health than their counterparts in the general population with higher rates of multi-morbidity, inactivity, and obesity. The reasons for this health disparity are unclear however it is known that SB and overall inactivity contribute to poorer health. There is no clear picture of the levels of SB among individuals with ID therefore SB levels in this vulnerable population need to be examined. The aim of this systematic review is to investigate the prevalence of sedentary behaviour in adults with an ID.  

Methods: The PRISMA-P framework was applied to identify high quality articles. An extensive search was carried out in four databases and grey literature sources . In total, 1,972 articles were retrieved of which 48 articles went forward for full review after duplicate removal and screening by title and abstract. The National Institute of Health’s quality assessment tools were used to assess article quality. Two reviewers independently assessed each article. An excel spreadsheet was created to guide the data extraction process. The final review included 25 articles. A meta-analysis was completed using REVMAN.  

Results: Different SB assessment types were identified in studies. These included steps, time, questionnaires, and screen time. Studies were heterogeneous. Observed daily steps per individual ranged from 44 to above 30,000, with an average of approximately 6,500 steps. Mean daily time spent in SBs was more than 60% of available time, with observed screen time of more than 3 hours. 

Conclusion: There is a high prevalence of SB in adults with an intellectual disability. 

 [Registration no: Index CRD42020177225].

Waist circumference was associated with 2-year blood pressure change in community dwelling adults independently of BMI

OBJECTIVE

The present study aimed to analyze the association of 2-year changes in BMI and waist circumference with changes in blood pressure (BP) in a randomized sample of community-dwelling adults.

METHODS

A sample of 331 middle-aged and older adults (mean age of 59.6 ± 17.3 years) was randomly selected. Measurements of SBP and DBP, BMI, and waist circumference were collected at baseline and after 2-year follow-up. Chronological age, sex, socioeconomic status, ethnicity, and self-reported medical diagnosis and use of medication for hypertension, diabetes, and high low-density lipoprotein-cholesterol were covariates. Multiple linear regression models were adopted for statistical analysis.

RESULTS

SBP was positively associated with BMI (β = 0.48, P = 0.013) and waist circumference (β = 0.21, P = 0.005) at baseline and only with waist circumference at follow-up (β = 0.20, P = 0.007). DBP was positively associated with BMI (β = 0.31, P = 0.009) and waist circumference (β = 0.12, P = 0.006) values at baseline and at follow-up (BMI β = 0.42, P = 0.001; waist circumference β = 0.18, P = 0.001). Only the 2-year changes in waist circumference were associated to changes in SBP (β = 0.33, P = 0.013), regardless of confounding factors and BMI.

CONCLUSION

It is suggested that waist circumference is the main factor for control over the time in strategies focused on BP management in adult population.

Step detection and energy expenditure at different speeds by three accelerometers in a controlled environment

Physical activity (PA) is one of the most efficient ways to prevent obesity and its associated diseases worldwide. In the USA, less than 10% of the adult population were able to meet the PA recommendations when accelerometers were used to assess PA habituation. Accelerometers significantly differ from each other in step recognition and do not reveal raw data. The aim of our study was to compare a novel accelerometer, Sartorio Xelometer, which enables to gather raw data, with existing accelerometers ActiGraph GT3X+ and activPAL in terms of step detection and energy expenditure estimation accuracy. 53 healthy subjects were divided into 2 cohorts (cohort 1 optimization; cohort 2 validation) and wore 3 accelerometers and performed an exercise routine consisting of the following speeds: 1.5, 3, 4.5, 9 and 10.5 km/h (6 km/h for 2nd cohort included). Data from optimization cohort was used to optimize Sartorio step detection algorithm. Actual taken steps were recorded with a video camera and energy expenditure (EE) was measured. To observe the similarity between video and accelerometer step counts, paired samples t test and intraclass correlation were used separately for step counts in different speeds and for total counts as well as EE estimations. In speeds of 1.5, 3, 4.5, 6, 9 and 10.5 km/h mean absolute percentage error (MAPE) % were 8.1, 3.5, 4.3, 4.2, 3.1 and 7.8 for the Xelometer, respectively (after optimization). For ActiGraph GT3X+ the MAPE-% were 96.93 (87.4), 34.69 (23.1), 2.13 (2.3), 1.96 (2.6) and 2.99 (3.8), respectively and for activPAL 6.55 (5.6), 1.59 (0.6), 0.81 (1.1), 10.60 (10.3) and 15.76 (13.8), respectively. Significant intraclass correlations were observed with Xelometer estimates and actual steps in all speeds. Xelometer estimated the EE with a MAPE-% of 30.3, activPAL and ActiGraph GT3X+ with MAPE percentages of 20.5 and 24.3, respectively. The Xelometer is a valid device for assessing step counts at different gait speeds. MAPE is different at different speeds, which is of importance when assessing the PA in obese subjects and elderly. EE estimates of all three devices were found to be inaccurate when compared with indirect calorimetry.

Energy Requirement for Elderly CKD Patients

The correct management of energy intake is crucial in CKD (chronic kidney disease) patients to limit the risk of protein energy wasting especially during low-protein regimes, but also to prevent overweight/obesity. The aim of this study was to assess the energy requirement of older CKD patients using objective measurements. This cross-sectional study enrolled 67 patients (aged 60-86 years) with CKD stages 3-5 not on dialysis, all of whom were metabolically and nutritionally stable. All patients underwent indirect calorimetry and measurement of daily physical activity level expressed by the average daily Metabolic Equivalent Task, using an accelerometer, in order to measure total energy expenditure (mTEE). Estimated TEE (eTEE) was derived from predictive equations for resting energy expenditure and physical activity levels coefficients. The mTEE were lower than eTEE-based on Harris-Benedict or Schofield or Mifflin equations (1689 ± 523 vs. 2320 ± 434 or 2357 ± 410 or 2237 ± 375 Kcal, p < 0.001, respectively). On average mTEE was 36.5% lower than eTEE. When eTEE was recalculated using ideal body weight the gap between mTEE and eTEE was reduced to 26.3%. A high prevalence of a sedentary lifestyle and reduced physical capabilities were also detected. In conclusion, our data support the energy intake of 25-35 Kcal/Kg/d recently proposed by the NKF-KDOQI (National Kidney Foundation-Kidney Disease Improving Quality Initiative) guidelines on nutritional treatment of CKD, which seem to be more adequate and applicable than that of previous guidelines (30-35 Kcal/Kg/d) in elderly stable CKD patients with a sedentary lifestyle. According to our findings we believe that an energy intake even lower than 25 Kcal/Kg/d may be adequate in metabolically stable, elderly CKD patients with a sedentary lifestyle.

Sedentary behaviour levels in adults with an intellectual disability: a systematic review and meta-analysis

Background: Sedentary behaviour (SB), which is characterised by low levels of energy expenditure, has been linked to increased cardio-metabolic risks, obesity and mortality, as well as cancer risk. No firm guidelines are established on safe levels of SB. Adults with an intellectual disability (ID) have poorer health than their counterparts in the general population with higher rates of multi-morbidity, inactivity, and obesity. The reasons for this health disparity are unclear however it is known that SB and overall inactivity contribute to poorer health. There is no clear picture of the levels of SB among individuals with ID therefore SB levels in this vulnerable population need to be examined. The aim of this systematic review is to investigate the prevalence of sedentary behaviour in adults with an ID.   Methods: The PRISMA-P framework was applied to identify high quality articles. An extensive search was carried out in four databases and grey literature sources . In total, 1,972 articles were retrieved of which 48 articles went forward for full review after duplicate removal and screening by title and abstract. The National Institute of Health's quality assessment tools were used to assess article quality. Two reviewers independently assessed each article. An excel spreadsheet was created to guide the data extraction process. The final review included 25 articles. A meta-analysis was completed using REVMAN.   Results: Different SB assessment types were identified in studies. These included steps, time, questionnaires, and screen time. Studies were heterogeneous. Observed daily steps per individual ranged from 44 to above 30,000, with an average of approximately 6,500 steps. Mean daily time spent in SBs was more than 60% of available time, with observed screen time of more than 3 hours.  Conclusion: There is a high prevalence of SB in adults with an intellectual disability.   [Registration no: Index CRD42020177225].

Sedentary behaviour levels in adults with an intellectual disability: a systematic review and meta-analysis

Background: Sedentary behaviour (SB), which is characterised by low levels of energy expenditure, has been linked to increased cardio-metabolic risks, obesity and mortality, as well as cancer risk. No firm guidelines are established on safe levels of SB. Adults with an intellectual disability (ID) have poorer health than their counterparts in the general population with higher rates of multi-morbidity, inactivity, and obesity. The reasons for this health disparity are unclear however it is known that SB and overall inactivity contribute to poorer health. There is no clear picture of the levels of SB among individuals with ID therefore SB levels in this vulnerable population need to be examined. The aim of this systematic review is to investigate the prevalence of sedentary behaviour in adults with an ID.   Methods: The PRISMA-P framework was applied to identify high quality articles. An extensive search was carried out in four databases and grey literature sources . In total, 1,972 articles were retrieved of which 48 articles went forward for full review after duplicate removal and screening by title and abstract. The National Institute of Health's quality assessment tools were used to assess article quality. Two reviewers independently assessed each article. An excel spreadsheet was created to guide the data extraction process. The final review included 25 articles. A meta-analysis was completed using REVMAN.   Results: Different SB assessment types were identified in studies. These included steps, time, questionnaires, and screen time. Studies were heterogeneous. Observed daily steps per individual ranged from 44 to above 30,000, with an average of approximately 6,500 steps. Mean daily time spent in SBs was more than 60% of available time, with observed screen time of more than 3 hours.  Conclusion: There is a high prevalence of SB in adults with an intellectual disability.   [Registration no: Index CRD42020177225].

Sex-specific differences in somatic investment and strategies of physical activity among Portuguese schoolchildren

OBJECTIVES

Physical activity (PA) is required for healthy growth, development, and maturation and plays an important role in the prevention of overweight and obesity in childhood and adolescence. Sex-differences in PA levels are well documented, with boys spending more time in PA, especially in moderate-to-vigorous activities. Following the Life History Theory, our aim is to study if PA affects the fat tissues increases during childhood and juvenile phases in both sexes.

METHODS

Time spent in sedentary, light, and moderate-to-vigorous PA levels were measured in a sample of 415 Portuguese children and juveniles (207 females/208 males; aged 6-11 years), using an accelerometer for 7 days. Skinfolds related with body fat were objectively collected and socioeconomic status factors were reported using a parental questionnaire.

RESULTS

The outcomes show that girls' and boys' fat variables increased during the end of the childhood and the juvenile phase. However, these variables were differently affected by PA. Girls increased fat variables with the sedentary activity while boys decreased fat variables with moderate-to-vigorous PA. Alike, active boys but not girls reduced the fat increase tendency with age.

CONCLUSIONS

Although both sexes displayed a general fat increment with age, moderate-to-vigorous PA dampens the increase only in boys. In fact, active girls increased body fat in the same manner as non-active girls. From an evolutionary perspective, it could explain sex-specific somatic strategies related to future reproduction or, with future mating and intrasexual competition.

How is television time linked to cardiometabolic health in adults? A critical systematic review of the evidence for an effect of watching television on eating, movement, affect and sleep

OBJECTIVE

To improve our understanding of how television (TV) time is linked to cardiometabolic health among adults by systematically and critically evaluating the evidence that watching TV is associated with increased food consumption, lack of movement or negative affect or affects subsequent sleep.

DESIGN

Systematic review.

DATA SOURCES

Web of Science and PubMed.

ELIGIBILITY CRITERIA

Studies that provided quantitative evidence on short-term associations of watching TV with dietary intake, characteristics of sitting, affect and sleep among samples of healthy adults (≥18 years old).

DATA EXTRACTION AND SYNTHESIS

Study quality was assessed using the National Heart, Lung, and Blood Institute Quality Assessment Tools; studies deemed to be of low quality were excluded from the review. Due to heterogeneity of study designs and measurements, the findings were synthesised using narrative summary accompanied by custom plots.

RESULTS

We identified 31 studies that met the inclusion criteria. Most of the associations reported by the studies included in this review were weak or inconsistent. There was no strong evidence to suggest that food consumption is higher while watching TV than in other contexts or that TV is a particularly 'sedentary' behaviour. Affect was less likely to be positive while watching TV than in other contexts but was not more likely to be negative. Two small studies suggest that TV may impact sleep via suppressing melatonin and delaying bedtime.

CONCLUSION

There is currently no strong evidence to suggest that TV might impact cardiometabolic health via increasing food consumption, being linked with prolonged/inactive sitting, affect or subsequent sleep. Additional research is required to understand how TV fits within everyday lives and relates to eating, sitting, affect and sleep to improve our understanding of how it might impact cardiometabolic health.

Sedentary behaviour levels in adults with an intellectual disability: a systematic review protocol

Background: Sedentary behaviour contributes to non-communicable diseases, which account for almost 71% of world deaths. Of these, cardiovascular disease is one of the largest causes of preventable death. It is not yet fully understood what level of sedentary behaviour is safe. People with an intellectual disability have poorer health than the general population with higher rates of multi-morbidity, obesity and inactivity. There is a paucity of evidence on whether this poorer health is due to sedentary behaviour or physical inactivity. This systematic review will investigate the sedentary behaviour levels of adults with an intellectual disability. Method: The PRISMA-P framework will be applied to achieve high-quality articles. An extensive search will be conducted in Medline, Embase, psycINFO and Cinahl and grey literature sources. All articles will be independently reviewed by two reviewers and a third to resolve disputes. Initially, the articles will be reviewed by title and abstract and then the full article will be reviewed using stringent inclusion criteria. All article data will be summarised in a standardised tabular format. The National Institute of Health's quality assessment tool will be used to assess article quality. GRADE will be used to assess the quality of the evidence. The primary outcome of interest is the prevalence of sedentary behaviour levels for people with an intellectual disability. The definition of sedentary behaviour to be used for the purposes of this study is: 'low physical activity as identified by metabolic equivalent (MET) or step levels or as measured by the Rapid Assessment of Physical activity questionnaire (RAPA) or the International Physical Activity questionnaire (IPAQ) or sitting for more than 3 hours per day'. Conclusion: This systematic review will provide a critical insight into the prevalence of sedentary behaviour in adults with an intellectual disability.

Reexamining the Energy Cost of Sedentary Behaviors From the 2011 Adult Compendium

BACKGROUND

This study reexamines the energy cost of lower intensity activities compared to the 2011 Adult Compendium of Physical Activities.

METHODS

Participants (n = 32, age = 35 [13.8] y, 16 females) wore a portable metabolic system (COSMED), during 5 different conditions: sitting quietly, watching TV, sitting while working, driving, and walking at 2.0 mph. The metabolic equivalent (MET) values (VO2 mL·kg-1·min-1/3.5 mL·kg-1·min-1) were calculated.

RESULTS

The mean (SD) MET value for driving (1.46 [0.24]) was significantly lower than the Adult Compendium value of 2.5 (P < .001). Driving and slow walking have similar Adult Compendium values, but driving METs were significantly lower than slow walking (P < .001). Driving was similar to sitting while working (1.32 [0.25] METs, P > .05) and yielded significantly higher MET values than quiet sitting (1.08 [0.23] METs, P < .001) and watching TV (1.12 [0.22] METs, P < .001), both of which were lower than their respective Adult Compendium MET values.

CONCLUSION

Existing Adult Compendium METs are significantly higher than measured METs for driving, which more closely correspond to sedentary behaviors than slow walking. The TV and quiet sitting also differed from their Adult Compendium values, which should be updated to reflect these findings, given that researchers and practitioners rely on Adult Compendium MET values to estimate energy cost.

Shorter Sleep Predicts Longer Subsequent Day Sedentary Duration in Healthy Midlife Adults, but Not in Those with Sleep Apnea

PURPOSE

Sedentary behavior and suboptimal sleep increase risks for chronic diseases. We hypothesized that sedentary behavior and sleep affect each other and that an underlying sleep disorder would alter these relationships. To test these hypotheses, we studied the bidirectional relationships between sedentary behavior and sleep (duration and efficiency) in healthy controls (HC) and people with untreated obstructive sleep apnea (OSA).

PATIENTS AND METHODS

Fifty-two volunteers (18 HC, 19 mild OSA [apnea/hypopnea index [AHI] range 5-14.9/hour], 15 moderate OSA [AHI range 15-29.9/hour]) were studied with actigraphy and sleep diaries across ~9 consecutive nights of self-selected consistent ~8-hour sleep episodes at home (range 4-21/nights per person). We analyzed whether total time asleep and sleep efficiency affected the subsequent daytime sedentary duration while controlling for body mass index and whether the severity of OSA altered this relationship. We also tested the reverse relationship, namely whether daytime sedentary duration affected the subsequent night's sleep and if any such relationship differed with OSA severity.

RESULTS

Overnight sleep duration and efficiency negatively predicted the subsequent day's sedentary duration in HC (p<0.02), but not in people with mild or moderate OSA (p>0.05). There was no significant reverse relationship between daytime sedentary duration and the subsequent night's sleep duration or efficiency (p≥0.2).

CONCLUSION

In healthy adults, short nighttime sleep predicts a longer duration of sedentary behavior on a subsequent day, but we did not observe this relationship in people with OSA. The mechanisms underlying this association in healthy individuals and its disruption in the presence of OSA need to be studied.

An appraisal of whole-room indirect calorimeters and a metabolic cart for measuring resting and active metabolic rates

Whole-room indirect calorimeters (WRICs) have traditionally been used for real-time resting metabolic rate (RMR) measurements, while metabolic rate (MR) during short-interval exercises has commonly been measured by metabolic carts (MCs). This study aims to investigate the feasibility of incorporating short-interval exercises into WRIC study protocols by comparing the performance of WRICs and an MC. We assessed the 40-min RMR of 15 subjects with 2-day repeats and the 10-15 min activity MR (AMR) of 14 subjects at three intensities, using a large WRIC, a small WRIC, and an MC. We evaluated the biases between the instruments and quantified sources of variation using variance component analysis. All three instruments showed good agreement for both RMR (maximum bias = 0.07 kcal/min) and AMR assessment (maximum bias = 0.53 kcal/min). Moreover, the majority of the variability was between-subject and between-intensity variation, whereas the types of instrument contributed only a small amount to total variation in RMR (2%) and AMR (0.2%) data. In Conclusion, the good reproducibility among the instruments indicates that they may be used interchangeably in well-designed studies. Overall, WRICs can serve as an accurate and versatile means of assessing MR, capable of integrating RMR and short-interval AMR assessments into a single protocol.

Sedentary behaviour levels in adults with an intellectual disability: a systematic review protocol

Background: Sedentary behaviour contributes to non-communicable diseases, which account for almost 71% of world deaths. Of these, cardiovascular disease is one of the largest causes of preventable death. It is not yet fully understood what level of sedentary behaviour is safe. People with an intellectual disability have poorer health than the general population with higher rates of multi-morbidity, obesity and inactivity. There is a paucity of evidence on whether this poorer health is due to sedentary behaviour or physical inactivity. This systematic review will investigate the sedentary behaviour levels of adults with an intellectual disability. Method: The PRISMA-P framework will be applied to achieve high-quality articles. An extensive search will be conducted in Medline, Embase, psycINFO and Cinahl and grey literature sources. All articles will be independently reviewed by two reviewers and a third to resolve disputes. Initially, the articles will be reviewed by title and abstract and then the full article will be reviewed using stringent inclusion criteria. All article data will be summarised in a standardised tabular format. The National Institute of Health's quality assessment tool will be used to assess article quality. GRADE will be used to assess the quality of the evidence. The primary outcome of interest is the prevalence of sedentary behaviour levels for people with an intellectual disability. The definition of sedentary behaviour to be used for the purposes of this study is: 'low physical activity as identified by metabolic equivalent (MET) or step levels or as measured by the Rapid Assessment of Physical activity questionnaire (RAPA) or the International Physical Activity questionnaire (IPAQ) or sitting for more than 3 hours per day'. Conclusion: This systematic review will provide a critical insight into the prevalence of sedentary behaviour in adults with an intellectual disability.

Sitting, squatting, and the evolutionary biology of human inactivity

Recent work suggests human physiology is not well adapted to prolonged periods of inactivity, with time spent sitting increasing cardiovascular disease and mortality risk. Health risks from sitting are generally linked with reduced levels of muscle contractions in chair-sitting postures and associated reductions in muscle metabolism. These inactivity-associated health risks are somewhat paradoxical, since evolutionary pressures tend to favor energy-minimizing strategies, including rest. Here, we examined inactivity in a hunter-gatherer population (the Hadza of Tanzania) to understand how sedentary behaviors occur in a nonindustrial economic context more typical of humans' evolutionary history. We tested the hypothesis that nonambulatory rest in hunter-gatherers involves increased muscle activity that is different from chair-sitting sedentary postures used in industrialized populations. Using a combination of objectively measured inactivity from thigh-worn accelerometers, observational data, and electromygraphic data, we show that hunter-gatherers have high levels of total nonambulatory time (mean ± SD = 9.90 ± 2.36 h/d), similar to those found in industrialized populations. However, nonambulatory time in Hadza adults often occurs in postures like squatting, and we show that these "active rest" postures require higher levels of lower limb muscle activity than chair sitting. Based on our results, we introduce the Inactivity Mismatch Hypothesis and propose that human physiology is likely adapted to more consistently active muscles derived from both physical activity and from nonambulatory postures with higher levels of muscle contraction. Interventions built on this model may help reduce the negative health impacts of inactivity in industrialized populations.

Effect of Morning Exercise With or Without Breaks in Prolonged Sitting on Blood Pressure in Older Overweight/Obese Adults

Both exercise and breaks in prolonged sitting can reduce blood pressure (BP) in older overweight/obese adults. We investigated whether there is an additive hypotensive effect when exercise is combined with subsequent breaks in sitting. Sex differences and changes in plasma catecholamines as a potential candidate mechanism underlying BP responses were also examined. Sedentary older adults (n=67; 67±7 years; 31.2±4.1 kg/m²) completed 3 conditions in random order-sitting (SIT): uninterrupted sitting (8 hours, control); exercise+sitting (EX+SIT): sitting (1 hour), moderate-intensity walking (30 minutes), uninterrupted sitting (6.5 hours); exercise+breaks (EX+BR): sitting (1 hour), moderate-intensity walking (30 minutes), sitting interrupted every 30 minutes with 3 minutes of light-intensity walking (6.5 hours). Serial BP and plasma epinephrine/norepinephrine measurements occurred during 8 hours. The 8-hour average systolic and diastolic BP (mm Hg 95% CI) was lower in EX+SIT -3.4 (-4.5 to -2.3), -0.8 (-1.6 to -0.04), and EX+BR -5.1 (-6.2 to -4.0), -1.1 (-1.8 to -0.3), respectively, relative to SIT (all P <0.05). There was an additional reduction in average systolic BP of -1.7 (-2.8 to -0.6) in EX+BR relative to EX+SIT ( P=0.003). This additional reduction in systolic BP was driven by women -3.2 (-4.7 to -1.7; P<0.001 EX+BR versus EX+SIT). Average epinephrine decreased in EX+SIT and EX+BR in women (-13% to -12%) but increased in men (+12% to +23%), respectively, relative to SIT ( P<0.05). No differences in average norepinephrine were observed. Morning exercise reduces BP during a period of 8 hours in older overweight/obese adults compared with prolonged sitting. Combining exercise with regular breaks in sitting may be of more benefit for lowering BP in women than in men. Clinical Trial Registration- URL: https://www.anzctr.org.au . Unique identifier: ACTRN12614000737639.

Accuracy of 12 Wearable Devices for Estimating Physical Activity Energy Expenditure Using a Metabolic Chamber and the Doubly Labeled Water Method: Validation Study

Background

Self-monitoring using certain types of pedometers and accelerometers has been reported to be effective for promoting and maintaining physical activity (PA). However, the validity of estimating the level of PA or PA energy expenditure (PAEE) for general consumers using wearable devices has not been sufficiently established.

Objective

We examined the validity of 12 wearable devices for determining PAEE during 1 standardized day in a metabolic chamber and 15 free-living days using the doubly labeled water (DLW) method.

Methods

A total of 19 healthy adults aged 21 to 50 years (9 men and 10 women) participated in this study. They followed a standardized PA protocol in a metabolic chamber for an entire day while simultaneously wearing 12 wearable devices: 5 devices on the waist, 5 on the wrist, and 2 placed in the pocket. In addition, they spent their daily lives wearing 12 wearable devices under free-living conditions while being subjected to the DLW method for 15 days. The PAEE criterion was calculated by subtracting the basal metabolic rate measured by the metabolic chamber and 0.1×total energy expenditure (TEE) from TEE. The TEE was obtained by the metabolic chamber and DLW methods. The PAEE values of wearable devices were also extracted or calculated from each mobile phone app or website. The Dunnett test and Pearson and Spearman correlation coefficients were used to examine the variables estimated by wearable devices.

Results

On the standardized day, the PAEE estimated using the metabolic chamber (PAEEcha) was 528.8±149.4 kcal/day. The PAEEs of all devices except the TANITA AM-160 (513.8±135.0 kcal/day; P>.05), SUZUKEN Lifecorder EX (519.3±89.3 kcal/day; P>.05), and Panasonic Actimarker (545.9±141.7 kcal/day; P>.05) were significantly different from the PAEEcha. None of the devices was correlated with PAEEcha according to both Pearson (r=−.13 to .37) and Spearman (ρ=−.25 to .46) correlation tests. During the 15 free-living days, the PAEE estimated by DLW (PAEEdlw) was 728.0±162.7 kcal/day. PAEE values of all devices except the Omron Active style Pro (716.2±159.0 kcal/day; P>.05) and Omron CaloriScan (707.5±172.7 kcal/day; P>.05) were significantly underestimated. Only 2 devices, the Omron Active style Pro (r=.46; P=.045) and Panasonic Actimarker (r=.48; P=.04), had significant positive correlations with PAEEdlw according to Pearson tests. In addition, 3 devices, the TANITA AM-160 (ρ=.50; P=.03), Omron CaloriScan (ρ=.48; P=.04), and Omron Active style Pro (ρ=.48; P=.04), could be ranked in PAEEdlw.

Conclusions

Most wearable devices do not provide comparable PAEE estimates when using gold standard methods during 1 standardized day or 15 free-living days. Continuous development and evaluations of these wearable devices are needed for better estimations of PAEE.

Sedentary Behavior, Physical Activity, and All-Cause Mortality: Dose-Response and Intensity Weighted Time-Use Meta-analysis

OBJECTIVES

Previous studies have placed those with excessive sedentary behavior at increased risk of all-cause mortality. There is evidence of interdependency of sedentary behavior with physical activity, and its elucidation will have implications for guidelines and practice. This study investigated if sedentary behavior-related mortality risk can be offset by moderate- to vigorous-intensity physical activity (MVPA) considered in a time-use fashion.

DESIGN

PubMed was searched (from its inception till May 2018) for studies or meta-analyses that used data harmonized for MVPA. Of the 17 data-custodians located, 7 provided data on sitting time or TV viewing time, or both. A dose-response meta-analysis modeling log relative risks of all-cause mortality against uncompensated sedentary behavior metabolic equivalent hours (USMh) was run using the robust error meta-regression method. (Registration: CRD42017062439) SETTING: Individual subject data held by data custodians on this topic.

PARTICIPANTS

General adults.

MEASUREMENTS

Sedentary time, MVPA.

RESULTS

Five harmonized cohorts of sitting time (258,688 participants) and 4 of TV viewing time (156,593 participants) demonstrated that sedentary behavior was significantly associated with mortality, but this risk was attenuated with increasing energy expenditure through MVPA modeled in a time-use fashion. The average increment in mortality per USMh spent on sitting was 1% [relative risk (RR) 1.01, 95% confidence interval (CI) 1.00, 1.02; P = .01] and that per USMh spent on TV viewing was 7% (RR 1.07, 95% CI 1.04, 1.10; P < .001). The thresholds for risk started at 7 USMh for sitting and 3 USMh for TV viewing.

CONCLUSIONS/IMPLICATIONS

Our findings suggest that overall daily sitting time energy expenditure of 7 MET-hours (or TV viewing of 3 MET-hours) in excess of that expended on MVPA is independently related to all-cause mortality. These findings support the view that sitting is strongly influenced by consideration of concurrent MVPA in its impact on adverse health consequences and that the USMh is a more practical metric of sedentary behavior.

Associations of context-specific sitting time with markers of cardiometabolic risk in Australian adults

Background

High volumes of sitting time are associated with an elevated risk of type 2 diabetes and cardiovascular disease, and with adverse cardiometabolic risk profiles. However, previous studies have predominately evaluated only total sitting or television (TV) viewing time, limiting inferences about the specific cardiometabolic health impacts of sitting accumulated in different contexts. We examined associations of sitting time in four contexts with cardiometabolic risk biomarkers in Australian adults.

Methods

Participants (n = 3429; mean ± SD age 58 ± 10 years) were adults without clinically diagnosed diabetes or cardiovascular disease from the 2011–2012 Australian Diabetes, Obesity and Lifestyle (AusDiab) study. Multiple linear regressions examined associations of self-reported context-specific sitting time (occupational, transportation, TV-viewing and leisure-time computer use) with a clustered cardiometabolic risk score (CMR) and with individual cardiometabolic risk biomarkers (waist circumference, BMI, resting blood pressure, triglycerides, HDL- and LDL-cholesterol, and fasting and 2-h post-load plasma glucose).

Results

Higher CMR was significantly associated with greater TV-viewing and computer sitting time (b [95%CI] = 0.07 [0.04, 0.09] and 0.06 [0.03, 0.09]), and tended to be associated with higher occupational and transport sitting time (0.01 [− 0.01, 0.03] and 0.03 [− 0.00, 0.06]), after adjustment for potential confounders. Furthermore, keeping total sitting time constant, accruing sitting via TV-viewing and computer use was associated with significantly higher CMR (0.05 [0.02, 0.08] and 0.04 [0.01, 0.06]), accruing sitting in an occupational context was associated with significantly lower CMR (− 0.03 [− 0.05, − 0.01]), while no significant association was seen for transport sitting (0.00 [− 0.03, 0.04]). Results varied somewhat between the respective biomarkers; however, higher sitting time in each domain tended to be associated detrimentally with individual biomarkers except for fasting glucose (non-significant associations) and systolic blood pressure (a beneficial association was observed). Overall, associations were stronger for TV-viewing and computer use, and weaker for occupational sitting.

Conclusions

Higher context-specific sitting times tended to be detrimentally associated, albeit modestly, with CMR and several cardiometabolic risk biomarkers. There was some evidence suggesting that the context in which people sit is relevant above and beyond total sitting time. Methodological issues notwithstanding, these findings may assist in identifying priorities for sitting-reduction initiatives, in order to achieve optimal cardiometabolic health benefits.

Electronic supplementary material

The online version of this article (10.1186/s12966-018-0748-3) contains supplementary material, which is available to authorized users.

The Necessity of Active Muscle Metabolism for Healthy Aging: Muscular Activity Throughout the Entire Day

There is more need for "a movement-movement" than ever before. The percentage of seniors in our population is rising exponentially. Sedentary lifestyles throughout the lifespan have become the norm, including inactive youth and a sedentary workforce. Preventable chronic diseases caused by sedentary living have both lowered the quality of life for those directly affected or their families, and have created an unsustainable economic dilemma. In this article, we explain that whether it is a sedentary student, worker, or retiree, the most neglected but essential facts are as follows. By far, the most potent and rapid way to raise the rate of healthy metabolic and cardiovascular processes is through the immediate benefits of muscle contractions. Working muscle demands more energy and fuel than any other tissue in the body, but during inactivity the metabolic rate of muscle is relatively low. Depending on the type of contraction, muscle type, and other factors, the local fuel requirements within the working muscle can help to manage metabolic risks through a variety of processes, such as blood glucose utilization, uptake of unhealthy blood triglycerides, and increased blood flow. Given the large amount of time that people spend inactive each day, there is an enormous opportunity to raise the bar in optimizing health throughout the entire lifespan. Developed correctly, safe and low effort muscular activity can be performed for relatively long periods of time each day by the elderly and all segments of the population to optimize health and well being during aging.

Sedentary Behaviors and Cardiometabolic Risk: An Isotemporal Substitution Analysis

Evidence suggests that time spent engaging in sedentary behaviors is associated with a greater risk of adverse cardiometabolic outcomes. We investigated the cross-sectional associations of 6 unique sedentary tasks (watching television, using the computer, completing paperwork, reading, talking on the telephone, and sitting in a car) with cardiometabolic risk factors, and also examined the effect of replacing one type of sedentary behavior with another on the level of cardiometabolic risk. Participants consisted of 3,211 individuals from the Coronary Artery Risk Development in Young Adults Study who visited the clinic between 2010 and 2011. Linear regression models examined the independent and joint associations of sedentary tasks with a composite cardiometabolic risk score, as well as with individual cardiometabolic risk factors (waist circumference, blood pressure, fasting glucose, insulin, triglycerides, and high density lipoprotein cholesterol) after adjusting for physical activity and other covariates. Replacing 2 hours of television viewing with 2 hours spent performing any other sedentary activity was associated with a lower cardiometabolic risk score of 0.06-0.09 standard deviations (all 95% confidence intervals: -0.13, -0.02). No other replacements of one type of sedentary task for another were significant. Study findings indicate that television viewing has a more adverse association with cardiometabolic risk factors than other sedentary behaviors.

Energy Expenditure of Standing Compared to Sitting While Conducting Office Tasks

Objectives This study aimed to investigate the energy expenditure of common office-based tasks. The objectives were to: (a) test the classification of tasks as sedentary or light-intensity physical activity and (b) compare the energy expenditure of tasks under two postural conditions (sitting and standing). Background The sedentary nature of office work has been highlighted as a health risk, and strategies to reduce sedentary behavior at work have been developed. However, there is limited evidence to guide the utilization of sit-stand workstations in the workplace for metabolic health benefits. Method A repeated measures laboratory-based study compared the energy expenditure of common office tasks in sitting and standing using indirect calorimetry ( n = 22). Four standardized tasks (sitting/standing quietly, reading, typing, sorting paper) under two postural conditions (sitting, standing) were performed in a randomized order. Results The mean energy expenditure for all tasks in sitting and standing was <1.5 METs. There were no significant differences in the energy expenditure of doing the same task in sitting compared to standing. In a repeated measures ANOVA, task ( p < .001) had a greater influence on METs expended than posture ( p = .030). Conclusion The study confirmed that the difference in energy expenditure of tasks carried out in sitting compared to standing is negligible. Application The ubiquitous use and utility of sit-stand workstations in the workplace needs to be reviewed. Notwithstanding the potential benefits of movement that may occur naturally, this study confirmed that standing as opposed to sitting does not produce a clinically important increase in energy expenditure.

Does the type of activity "break" from prolonged sitting differentially impact on postprandial blood glucose reductions? An exploratory analysis

Frequent breaks in prolonged sitting are associated beneficially with glycaemic control. However, the contribution of energy expenditure to this relationship has not been well characterised. In this exploratory analysis, data from 3 laboratory trials that standardised test meals, cohort characteristics (overweight/obese, sedentary), and break frequency and duration were pooled. Higher energy expenditures of different types of breaks (standing, light- or moderate-intensity walking) were associated with lower postprandial glucose and insulin responses in a dose-dependent manner.

Sedentary behaviour is associated with increased long-term cardiovascular risk in patients with rheumatoid arthritis independently of moderate-to-vigorous physical activity

BACKGROUND

Rheumatoid Arthritis (RA) is associated with an increased risk of cardiovascular disease (CVD). The physical dysfunction symptomatic of RA means people living with this disease spend large periods of the day sedentary, which may further elevate their risk of CVD. The primary aim of this study was to investigate relationships between objectively assessed sedentary behaviour patterns and light physical activity (LPA) with 10-year risk of CVD. Secondary aims were to explore the role of sedentary behaviour patterns and LPA for individual CVD risk factors and functional disability in RA. The extent to which associations were independent of moderate-to-vigorous physical activity (MVPA) engagement was also examined.

METHODS

Baseline data from a subsample of participants recruited to the Physical Activity in Rheumatoid Arthritis (PARA) study were used to answer current research questions. Sixty-one patients with RA (mean age (± SD) = 54.92 ± 12.39 years) provided a fasted blood sample and underwent physical assessments to evaluate factors associated with their cardiovascular health. Sedentary behaviour patterns (sedentary time, sedentary bouts, sedentary breaks), LPA and MVPA were measured via 7-days of accelerometry. Ten-year CVD risk was computed (Q-risk-score2), and functional disability determined via questionnaire.

RESULTS

Regressions revealed significant positive associations between sedentary time and the number of sedentary bouts per day ≥20 min with 10-year CVD risk, with the reverse true for LPA participation. Associations were independent of MVPA engagement.

CONCLUSIONS

Promoting LPA participation and restricting sedentary bouts to <20 min may attenuate long-term CVD risk in RA, independent of MVPA engagement.

TRIAL REGISTRATION

ISRCTN04121489 (retrospectively registered 19/10/2012).

Implications of sit-stand and active workstations to counteract the adverse effects of sedentary work: A comprehensive review

BACKGROUND

Sedentary work is associated with many adverse health outcomes, and sit-stand workstations in offices have emerged as a way to counteract sedentary work.

OBJECTIVE

This paper reviews the existing knowledge on sit-stand workstations, treadmill workstations and bicycle workstations.

METHODS

The inclusion/exclusion criteria were: 1) empirical research examining the effectiveness of sit-stand workstations in lab or field studies, 2) working adult population, 3) sit-stand workstation interventions where workers performed the same task from a seated or standing position, 4) outcomes measures of discomfort (comfort), performance, sit-stand behaviors, user satisfaction, kinematic and physiological measures. Search terms were: sit-stand, treadmill, bicycle, workstations, sedentary behavior, office ergonomics, and comfort.

RESULTS

Many studies considered productivity, comfort and physiological measures as important outcomes to assess the efficacy of sit-stand workstations and the experimental design was variable. Preliminary data suggests that some amount of standing during an 8-hour workday could be beneficial without compromising user comfort or productivity; however, there is very little data on the efficacy of treadmill and bicycle workstations.

CONCLUSIONS

Based on these preliminary data from 26 studies, conducting large scale randomized controlled trials with ergonomic training as their essential component is recommended to understand the benefits of sit-stand workstations for prevention of sedentary work.

What is the metabolic and energy cost of sitting, standing and sit/stand transitions?

PURPOSE

Modern lifestyles require people to spend prolonged periods of sitting, and public health messages recommend replacing sitting with as much standing as is feasible. The metabolic/energy cost (MEC) of sitting and standing is poorly understood, and MEC associated with a transition from sitting to standing has not been reported. Thus, we carefully quantified the MEC for sitting, standing and sit/stand transitions, adjusting for age and fat-free mass (FFM) in a sample of adults with no known disease.

METHODS

Participants (N = 50; 25 women), 20–64 years, randomly performed three conditions for 10 min each (sitting, standing, 1 sit/stand transition min(−1) and then sitting back down). MEC was measured by indirect calorimetry and FFM by dual-energy X-ray absorptiometry.

RESULTS

V̇O2 (ml kg(−1) min(−1)) for sitting (2.93 ± 0.61; 2.87 ± 0.37 in men and women respectively), standing (3.16 ± 0.63; 3.03 ± 0.40), and steady-state cost of repeated sit/stand transitions (1 min(−1)) (3.86 ± 0.75; 3.79 ± 0.57) were significantly different regardless of sex and weight (p < 0.001). EE (kcal min(−1)) also differed from sitting (1.14 ± 0.18; 0.88 ± 0.11), to standing (1.23 ± 0.19; 0.92 ± 0.13), and sit/stand transitions (1 min(−1)) (1.49 ± 0.25; 1.16 ± 0.16). Heart-rate increased from sitting to standing (~13 bpm; p < 0.001). Neither sex nor FFM influenced the results (p ≥ 0.05).

CONCLUSIONS

This study found in a sample of adults with no known disease that continuous standing raised MEC 0.07 kcal min(−1) above normal sitting. The transition from sitting to standing (and return to sitting) had a metabolic cost of 0.32 kcal min(−1) above sitting. Therefore, public health messages recommending to interrupt sitting frequently should be informed of the modest energetic costs regardless of sex and body composition.

Behavioral response to a just-in-time adaptive intervention (JITAI) to reduce sedentary behavior in obese adults: Implications for JITAI optimization

OBJECTIVE

Just-in-time adaptive interventions (JITAIs) use mobile computers, sensors, and software analytics to automatically detect behavior and deliver tailored treatment. However, little is known about how JITAIs influence patterns of behavior or how best to design JITAIs for maximum effect.

METHOD

This study examined prompts and behavioral response to the B-MOBILE JITAI for reducing sedentary behavior (SB) in overweight/obese individuals. Thirty participants (83% women; 67% White, mean ± SD body mass index = 36.2 kg/m2) tested 3 conditions presented in a randomized counterbalanced order involving smartphone-based prompts for walking breaks of (a) 3 min after 30 SB min, (b) 6 min after 60 SB min, and (c) 12 min after 120 SB min.

RESULTS

Participants carried the smartphone an average of 6.90 days during each 7-day condition, for an average of 14.94 hr per day. The 3- and 6-min conditions resulted in the greatest number of prompts, walking breaks, the best adherence to prompts, the greatest amount of daily time spent in walking breaks, and fastest adherence to prompts (ps < .01). Small but statistically significant decreases in the number of daily walking breaks, adherence to prompts, and minutes per day spent in walking breaks were observed as a function of the number of days spent in a condition (ps < .05).

CONCLUSIONS

The B-MOBILE JITAI was effective in prompting breaks in sedentary behavior when it was most clinically relevant. Frequent prompts for small change may be an optimal strategy for shaping sedentary behavior, although more research is needed to determine how best to promote long-term adherence.

Characterizing Energy Expenditure During Sedentary Behavior After Stroke

OBJECTIVES

To measure and calculate the energy expended by people with stroke during near sedentary behaviors (lying, supported and unsupported sitting, standing, wheelchair propulsion, walking), under controlled laboratory conditions, and to compare these values with the energy expenditure of 1.5 metabolic equivalent task (MET) within the definition of sedentary behavior.

DESIGN

Cross-sectional cohort study.

SETTING

Rehabilitation institutions.

PARTICIPANTS

People with stroke (N=27; mean age, 61.0±11.7y), categorized at Functional Ambulation Categories (FAC) 0 to 5.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Energy expenditure (measured using indirect calorimetry) expressed in METs. The recorded values were calculated for every participant and averaged for each activity: lying, supported and unsupported sitting, standing, wheelchair propulsion, and walking. Calculations were done for the total group and categorized by the FAC.

RESULTS

For the total group the mean METs ± SDs were 1.04±.11 for sitting supported, 1.09±.15 for sitting unsupported, 1.31±.25 for standing, 1.91±.42 for wheelchair propulsion, and 2.52±.55 for walking. People with stroke in all FAC had METs values >1.5 when propelling a wheelchair or walking.

CONCLUSIONS

Energy expenditure during typical sedentary behaviors (ie, sitting) is narrowly bounded at approximately 1.0 MET. Energy expenditure during sitting and standing was ≤1.5 MET for all FAC, with the exception of FAC 0 (1.6 MET during standing). Independent wheelchair propulsion and walking can be categorized as light activities (≥1.5 MET).

Energy expenditure during common sitting and standing tasks: examining the 1.5 MET definition of sedentary behaviour

Background

Sedentary behavior is defined as any waking behavior characterized by an energy expenditure of 1.5 METS or less while in a sitting or reclining posture. This study examines this definition by assessing the energy cost (METs) of common sitting, standing and walking tasks.

Methods

Fifty one adults spent 10 min during each activity in a variety of sitting tasks (watching TV, Playing on the Wii, Playing on the PlayStation Portable (PSP) and typing) and non-sedentary tasks (standing still, walking at 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, and 1.6 mph). Activities were completed on the same day in a random order following an assessment of resting metabolic rate (RMR). A portable gas analyzer was used to measure oxygen uptake, and data were converted to units of energy expenditure (METs).

Results

Average of standardized MET values for screen-based sitting tasks were: 1.33 (SD: 0.24) METS (TV), 1.41 (SD: 0.28) (PSP), and 1.45 (SD: 0.32) (Typing). The more active, yet still seated, games on the Wii yielded an average of 2.06 (SD: 0.5) METS. Standing still yielded an average of 1.59 (SD: 0.37) METs. Walking MET values increased incrementally with speed from 2.17 to 2.99 (SD: 0.5 - 0.69) METs.

Conclusions

The suggested 1.5 MET threshold for sedentary behaviors seems reasonable however some sitting based activities may be classified as non-sedentary. The effect of this on the definition of sedentary behavior and associations with metabolic health needs further investigation.

Light Intensity physical activity and sedentary behavior in relation to body mass index and grip strength in older adults: cross-sectional findings from the Lifestyle Interventions and Independence for Elders (LIFE) study

Background

Identifying modifiable determinants of fat mass and muscle strength in older adults is important given their impact on physical functioning and health. Light intensity physical activity and sedentary behavior are potential determinants, but their relations to these outcomes are poorly understood. We evaluated associations of light intensity physical activity and sedentary time—assessed both objectively and by self-report—with body mass index (BMI) and grip strength in a large sample of older adults.

Methods

We used cross-sectional baseline data from 1130 participants of the Lifestyle Interventions and Independence for Elders (LIFE) study, a community-dwelling sample of relatively sedentary older adults (70-89 years) at heightened risk of mobility disability. Time spent sedentary and in light intensity activity were assessed using an accelerometer worn for 3–7 days (Actigraph GT3X) and by self-report. Associations between these exposures and measured BMI and grip strength were evaluated using linear regression.

Results

Greater time spent in light intensity activity and lower sedentary times were both associated with lower BMI. This was evident using objective measures of lower-light intensity, and both objective and self-reported measures of higher-light intensity activity. Time spent watching television was positively associated with BMI, while reading and computer use were not. Greater time spent in higher but not lower intensities of light activity (assessed objectively) was associated with greater grip strength in men but not women, while neither objectively assessed nor self-reported sedentary time was associated with grip strength.

Conclusions

In this cross-sectional study, greater time spent in light intensity activity and lower sedentary times were associated with lower BMI. These results are consistent with the hypothesis that replacing sedentary activities with light intensity activities could lead to lower BMI levels and obesity prevalence among the population of older adults. However, longitudinal and experimental studies are needed to strengthen causal inferences.

Adiposity and insufficient MVPA predict cardiometabolic abnormalities in adults

OBJECTIVES

The purpose of this study is to compare the extent to which different combinations of objectively measured sedentary behavior (SB) and physical activity contribute to cardiometabolic health.

DESIGN AND METHODS

A population representative sample of 5268 individuals, ages 20-85 yr, was included from the combined 2003-2006 National Health and Nutrition Examination Survey datasets. Activity categories were created on the combined basis of objectively measured SB and moderate-to-vigorous physical activity (MVPA) tertiles. Cardiometabolic abnormalities included elevated blood pressure, levels of triglycerides, fasting plasma glucose, C-reactive protein, homeostasis model assessment of insulin resistance value, and low HDL cholesterol level. Body mass index and dual-energy x-ray absorptiometry-derived percent body fat and android adiposity were also compared across groups. Predictors for a metabolically abnormal phenotype (≥3 cardiometabolic abnormalities or insulin resistance) were determined.

RESULTS

Adults with the least SB and greatest MVPA exhibited the healthiest cardiometabolic profiles, whereas adults with the greatest SB and lowest MVPA were older and had elevated risk. Time spent in SB was not a predictor of the metabolically abnormal phenotype when MVPA was accounted for. Adults with the highest MVPA across SB tertiles did not differ markedly in prevalence of obesity, adiposity, and/or serum cardiometabolic risk factors; however, less MVPA was associated with substantial elevations of obesity and cardiometabolic risk. Android adiposity (per kilogram) was independently associated with the metabolically abnormal phenotype in both men (odds ratio, 2.36 (95% CI, 1.76-3.17), P < 0.001) and women (odds ratio, 2.00 (95% CI, 1.63-2.45), P < 0.001). Among women, greater SB and less lifestyle moderate activity and MVPA were each independently associated with the metabolically abnormal phenotype, whereas only less MVPA was associated with it in men.

CONCLUSIONS

MVPA is a strong predictor of cardiometabolic health among adults, independent of time spent in SB.

Sleep duration and cardiometabolic risk factors among individuals with type 2 diabetes

OBJECTIVE

To examine the association between sleep duration and cardiometabolic risk factors among individuals with recently diagnosed type 2 diabetes (n = 391).

METHODS

Sleep duration was derived using a combination of questionnaire and objective heart rate and movement sensing in the UK ADDITION-Plus study (2002-2007). Adjusted means were estimated for individual cardiometabolic risk factors and clustered cardiometabolic risk (CCMR) by five categories of sleep duration.

RESULTS

We observed a J-shaped association between sleep duration and CCMR - individuals sleeping 7 to <8 h had a significantly better CCMR profile than those sleeping ≥9 h. Independent of physical activity and sedentary time, individuals sleeping 7 to <8 h had lower triacylglycerol (0.62 mmol/l (0.29, 1.06)) and higher high-density lipoprotein (HDL)-cholesterol levels (0.23 mmol/l (0.16, 0.30)) compared with those sleeping ≥9 h, and a lower waist circumference (7.87 cm (6.06, 9.68)) and body mass index (BMI) (3.47 kg/m(2) (2.69, 4.25)) than those sleeping <6 h. Although sleeping 7 to <8 h was associated with lower levels of systolic and diastolic blood pressure, HbA1c, total cholesterol, and low-density lipoprotein (LDL)-cholesterol, these associations were not statistically significant.

CONCLUSIONS

Sleep duration has a J-shaped association with CCMR in individuals with diabetes, independent of potential confounding. Health promotion interventions might highlight the importance of adequate sleep in this high-risk population.

Distinct associations of different sedentary behaviors with health-related attributes among older adults

OBJECTIVE

Leisure-time sedentary behaviors (LTSBs) have been associated adversely with health outcomes. However, limited research has focused on different categories of LTSB. We aimed at identifying categories of LTSBs and examining their separate associations with indices of health among Japanese older adults.

METHODS

A postal survey collected data on self-reported health, psychological distress, body mass index, moderate-to-vigorous physical activity (MVPA), LTSBs (five behaviors) and socio-demographic characteristics from 1,580 Japanese older adults (67% response rate; 65-74 years) in 2010. Exploratory factor analysis was used to classify LTSBs. Odds ratios (ORs) were calculated for associations of LTSB categories with self-reported health, psychological distress, overweight, and lower MVPA. Data were analyzed in 2013.

RESULTS

Two categories of LTSB: passive sedentary time (consisting of TV time, listening or talking while sitting, and sitting around) and mentally-active sedentary time (consisting of computer-use and reading books or newspapers) were identified. Higher passive sedentary time was associated with a higher odds of being overweight (OR: 1.39, [95% CI: 1.08-1.80]), and lower MVPA (1.26, [1.02-1.54]). Higher mentally-active sedentary time was associated with lower odds of lower MVPA (0.70, [0.57-0.86]).

CONCLUSIONS

Two types of sedentary time-passive and mentally-active-may play different roles in older adults' well-being.

Appropriateness of the definition of 'sedentary' in young children: Whole-room calorimetry study

OBJECTIVES

The present study aimed to measure the energy cost of three common sedentary activities in young children to test whether energy expended was consistent with the recent consensus definition of 'sedentary' as 'any behaviour conducted in a sitting or reclining posture and with an energy cost ≤ 1.5 metabolic equivalents (METs)' (Sedentary Behaviour Research Network, 2012).

DESIGN

Observational study.

METHODS

Whole-room calorimetry measures of television viewing, sitting at a table drawing and reading, and sitting on the floor playing with toys were made in 40 young children (mean age 5.3 years, SD 1.0).

RESULTS

The energy cost of each sedentary activity was consistent with the recent consensus definition of sedentary: 1.17 METs (95% CI 1.07-1.27) for TV viewing; 1.38 METs (95% CI 1.30-1.46) for sitting at a table; and 1.35 METs (95% CI 1.28-1.43) for floor-based play.

CONCLUSIONS

Common sedentary activities in young children have energy costs which are consistent with the recent consensus definition of 'sedentary', and the present study is supportive of this definition.

Effects of subtracting sitting versus adding exercise on glycemic control and variability in sedentary office workers

Recent evidence suggests that, like adding exercise, reducing sitting time may improve cardiometabolic health. There has not been a direct comparison of the 2 strategies with energy expenditure held constant. The purpose of this study was to compare fasting and postmeal glucose and insulin concentrations in response to a day with frequent breaks from sitting but no exercise versus considerable sitting plus moderate exercise. Ten sedentary overweight/obese office workers were tested in 3 conditions: (i) walking per activity guidelines (AGW): sitting for majority of workday with a 30 min pre-lunch walk; (ii) frequent long breaks (FLB): no structured exercise but frequent breaks from sitting during workday with energy expenditure matched to AGW; and (iii) frequent short breaks (FSB): number of breaks matched to FLB, but duration of breaks were shorter. Plasma glucose and insulin areas under the curve were measured in response to a meal tolerance test (MTT) at the end of the workday and interstitial glucose was evaluated throughout the day and overnight using continuous glucose monitoring. Using repeated-measures linear mixed models, area under the curve of plasma glucose or insulin after the MTT was not different between conditions. Glycemic variability was lower in FLB compared with AGW (p < 0.05), and nocturnal duration of elevated glucose (>7.8 mmol/L) was shorter after FLB (2.5 ± 2.5 min) than AGW (32.7 ± 16.4 min) or FSB (45.6 ± 29.6 min, p = 0.05). When energy expenditure was matched, breaks from sitting approximated the effects of moderate-intensity exercise on postmeal glucose and insulin responses and more effectively constrained glycemic variability.

B-MOBILE--a smartphone-based intervention to reduce sedentary time in overweight/obese individuals: a within-subjects experimental trial

PURPOSE

Excessive sedentary time (SED) has been linked to obesity and other adverse health outcomes. However, few sedentary-reducing interventions exist and none have utilized smartphones to automate behavioral strategies to decrease SED. We tested a smartphone-based intervention to monitor and decrease SED in overweight/obese individuals, and compared 3 approaches to prompting physical activity (PA) breaks and delivering feedback on SED.

DESIGN AND METHODS

Participants [N = 30; Age = 47.5(13.5) years; 83% female; Body Mass Index (BMI) = 36.2(7.5) kg/m2] wore the SenseWear Mini Armband (SWA) to objectively measure SED for 7 days at baseline. Participants were then presented with 3 smartphone-based PA break conditions in counterbalanced order: (1) 3-min break after 30 SED min; (2) 6-min break after 60 SED min; and (3) 12-min break after 120 SED min. Participants followed each condition for 7 days and wore the SWA throughout.

RESULTS

All PA break conditions yielded significant decreases in SED and increases in light (LPA) and moderate-to-vigorous PA (MVPA) (p<0.005). Average % SED at baseline (72.2%) decreased by 5.9%, 5.6%, and 3.3% [i.e. by mean (95% CI) -47.2(-66.3, -28.2), -44.5(-65.2, -23.8), and -26.2(-40.7, -11.6) min/d] in the 3-, 6-, and 12-min conditions, respectively. Conversely, % LPA increased from 22.8% to 26.7%, 26.7%, and 24.7% [i.e. by 31.0(15.8, 46.2), 31.0(13.6, 48.4), and 15.3(3.9, 26.8) min/d], and % MVPA increased from 5.0% to 7.0%, 6.7%, and 6.3% (i.e. by 16.2(8.5, 24.0), 13.5(6.3, 20.6), and 10.8(4.2, 17.5) min/d] in the 3-, 6-, and 12-min conditions, respectively. Planned pairwise comparisons revealed the 3-min condition was superior to the 12-min condition in decreasing SED and increasing LPA (p<0.05).

CONCLUSION

The smartphone-based intervention significantly reduced SED. Prompting frequent short activity breaks may be the most effective way to decrease SED and increase PA in overweight/obese individuals. Future investigations should determine whether these SED reductions can be maintained long-term.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01688804.