Sedentary behavior, recreational physical activity, and 7-year weight gain among postmenopausal U.S. women

A comprehensive evaluation of predictors of obesity in women during the perimenopausal period: A systematic review and narrative synthesis

INTRODUCTION

Obesity during perimenopausal transition can be attributed to various factors. Identifying these factors is crucial in preventing obesity and developing effective strategies to manage weight during this phase. This review aimed to systematically understand predictors of obesity during menopausal transition.

METHODS

The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and searched databases like PubMed, Wiley Online Library, and Cochrane Reviews. Cohort and cross-sectional studies in English language assessing obesity among menopausal women were included. The methodological quality was assessed using Joanna Briggs Checklist for critical appraisal. Risk of Bias (RoB) was generated using Review Manager 5.4.1 (RevMan). Identified predictors were assessed for overall quality of evidence using adopted Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

RESULTS

This review encompassed 42 studies, (21 cross-sectional and 21 cohort) with sample ranging from 164 to 107,243 across studies. Higher parity( ≥ 3 children) emerged as a strong predictor of obesity across seven studies, with good-quality evidence. Lower physical activity was another predictor, supported by eight studies with good-quality evidence. Sociodemographic factors like lower education(<8 years or < than college degree), socioeconomic background, menopausal transition, and older age at menarche showed associations with weight gain, with moderate-quality evidence. Lifestyle factors (high-fat consumption, sedentariness, active smoking status, and psychological difficulties) also showed moderate-quality evidence.

CONCLUSION

This review underscores the multifaceted factors associated with obesity during the perimenopausal transition. Identifying these factors will be helpful in prevention and management of obesity among these women.

The bidirectional associations between leisure time physical activity change and body mass index gain. The Tromsø Study 1974-2016

OBJECTIVES

To examine whether leisure time physical activity changes predict subsequent body mass index (BMI) changes, and conversely, whether BMI changes predict subsequent leisure time physical activity changes.

METHODS

This prospective cohort study included adults attending ≥3 consecutive Tromsø Study surveys (time: T1, T2, T3) during 1974-2016 (n = 10779). If participants attended >3 surveys, we used the three most recent surveys. We computed physical activity change (assessed by the Saltin-Grimby Physical Activity Level Scale) from T1 to T2, categorized as Persistently Inactive (n = 992), Persistently Active (n = 7314), Active to Inactive (n = 1167) and Inactive to Active (n = 1306). We computed BMI change from T2 to T3, which regressed on preceding physical activity changes using analyses of covariance. The reverse association (BMI change from T1 to T2 and physical activity change from T2 to T3; n = 4385) was assessed using multinomial regression.

RESULTS

Average BMI increase was 0.86 kg/m² (95% CI: 0.82-0.90) from T2 to T3. With adjustment for sex, birth year, education, smoking and BMI at T2, there was no association between physical activity change from T1 to T2 and BMI change from T2 to T3 (Persistently Inactive: 0.89 kg/m² (95% CI: 0.77-1.00), Persistently Active: 0.85 kg/m² (95% CI: 0.81-0.89), Active to Inactive: 0.90 kg/m² (95% CI: 0.79-1.00), Inactive to Active 0.85 kg/m² (95% CI: 0.75-0.95), p = 0.84). Conversely, increasing BMI was associated with Persistently Inactive (odds ratio (OR): 1.17, 95% CI: 1.08-1.27, p < 0.001) and changing from Active to Inactive (OR: 1.16, 95% CI: 1.07-1.25, p < 0.001) compared with being Persistently Active.

CONCLUSIONS

We found no association between leisure time physical activity changes and subsequent BMI changes, whereas BMI change predicted subsequent physical activity change. These findings indicate that BMI change predicts subsequent physical activity change at population level and not vice versa.

A Narrative Review of the Role of Diet and Lifestyle Factors in the Development and Prevention of Endometrial Cancer

Simple Summary

The incidence and prevalence of endometrial cancer is increasing globally. The main factors involved in this increase have been the way women live today and what they eat and drink. In fact, the obesity pandemic that is sweeping across the planet is considered to be the main contributory feature. This review aims to introduce to a new audience, those that are not experts in the field, what is known about the different types of endometrial cancer and the mechanisms for their induction and protection. We also seek to summarise the existing knowledge on dietary and lifestyle factors that prevent endometrial development in susceptible populations and identify the main problem in this arena; the paucity of research studies and clinical trials that investigate the interaction(s) between diet, lifestyle and endometrial cancer risk whilst highlighting those areas of promise that should be further investigated.

Abstract

Endometrial cancer is the most common cancer affecting the reproductive organs of women living in higher-income countries. Apart from hormonal influences and genetic predisposition, obesity and metabolic syndrome are increasingly recognised as major factors in endometrial cancer risk, due to changes in lifestyle and diet, whereby high glycaemic index and lipid deposition are prevalent. This is especially true in countries where micronutrients, such as vitamins and minerals are exchanged for high calorific diets and a sedentary lifestyle. In this review, we will survey the currently known lifestyle factors, dietary requirements and hormonal changes that increase an individual’s risk for endometrial cancer and discuss their relevance for clinical management. We also examine the evidence that everyday factors and clinical interventions have on reducing that risk, such that informed healthy choices can be made. In this narrative review, we thus summarise the dietary and lifestyle factors that promote and prevent the incidence of endometrial cancer.

Sedentary work and breast cancer risk: A systematic review and meta-analysis

OBJECTIVES

This systematic review and meta-analysis aimed to assess sedentary work's contribution to breast cancer risk quantitatively using thorough research articles.

METHODS

We performed a meta-analysis using a registered protocol in PROSPERO (registration number: CRD42020204629). Literature from PubMed, Embase, and Cochrane involving sedentary work and breast cancer risk was reviewed. We calculated the overall pooled risk ratios (RRs) and 95% CI with a random-effect model from the included studies. Furthermore, we performed stratified analyses by characteristics of studies.

RESULTS

Thirty-one studies (13 cohort studies and 18 case-control studies) were included in the analysis. The overall effect of the pooled analysis was an RR of 1.16 (95% CI 1.08-1.23). The results were 1.20 (95% CI 1.10-1.30) and 1.12 (95% CI 1.02-1.23) for cohort and case-control studies. The effect of sedentary work did not seem to be consistently attenuated by controlling body mass index, menopausal status, or experience of hormone replacement therapy.

CONCLUSION

The results from this meta-analysis suggest that sedentary behavior within the occupational domain was associated with a 15.5% increased risk of breast cancer. It is essential to reduce the sedentary time spent at work and to secure time for leisure-time physical activity among sedentary workers as a primary preventive measure.

Strategies for Physical Activity Interventions in the Treatment of Obesity

Physical activity contributes to body weight regulation. At least 150 minutes per week of moderate-to-vigorous intensity physical activity may be needed. When not coupled with dietary restriction, physical activity contributes to an average weight loss of approximately 2 to 3 kg in interventions up to 6 months in duration; when added to modest dietary restriction it adds 20% additional weight loss compared with modest dietary restriction alone. Physical activity is associated with enhanced long-term weight loss and attenuation of weight regain and should be included within clinical and public health approaches to prevent weight regain and to treat obesity.

Physical Activity and the Prevention of Weight Gain in Adults: A Systematic Review

PURPOSE

To conduct a systematic literature review to determine if physical activity is associated with prevention of weight gain in adults.

METHODS

The primary literature search was conducted for the 2018 Physical Activity Guidelines Advisory Committee and encompassed literature through June 2017, with an additional literature search conducted to include literature published through March 2018 for inclusion in this systematic review.

RESULTS

The literature review identified 40 articles pertinent to the research question. There is strong evidence of an association between physical activity and prevention of weight gain in adults, with the majority of the evidence from prospective cohort studies. Based on limited evidence in adults, however, there is a dose-response relationship and the prevention of weight gain is most pronounced when moderate-to-vigorous intensity physical activity (≥3 METs) is above 150 min·wk. Although there is strong evidence to demonstrate that the relationship between greater time spent in physical activity and attenuated weight gain in adults is observed with moderate-to-vigorous intensity physical activity, there is insufficient evidence available to determine if there is an association between light-intensity activity (<3 METs) and attenuated weight gain in adults.

CONCLUSIONS

The scientific evidence supports that physical activity can be an effective lifestyle behavior to prevent or minimize weight gain in adults. Therefore, public health initiatives to prevent weight gain, overweight, and obesity should include physical activity as an important lifestyle behavior.

Physical Activity in the Prevention of Weight Gain: the Impact of Measurement and Interpretation of Associations

PURPOSE OF REVIEW

To what extent do different methods of physical activity measurement and statistical analysis influence the reported associations between physical activity and weight gain?

RECENT FINDINGS

The obesity epidemic has led to a focus on lifestyle approaches to the prevention of weight gain. Physical activity is one such approach. A number of studies have reported beneficial associations between higher levels of physical activity and weight gain at the population level. However, limitations of physical activity measurement and analytical models in some of these studies are likely to have resulted in overestimation of the strength of association. Understanding the limitations of assessment methods and analytical models used in epidemiological research should facilitate more realistic appraisal for physical activity to prevent weight gain at the population level and inform approaches to future research.

Exercise Dose Effects on Body Fat 12 Months after an Exercise Intervention: Follow-up from a Randomized Controlled Trial

BACKGROUND

Exercise interventions can result in weight loss, which is associated with reductions in disease risk. It is unknown how the volume of exercise prescribed in a one-time exercise intervention impacts long-term body fatness. We compared 24-month body fat changes among postmenopausal women previously prescribed 300 versus 150 minutes/week of exercise in a year-long exercise intervention trial.

METHODS

The Breast Cancer and Exercise Trial in Alberta (BETA) was a two-centred randomized controlled trial in Alberta, Canada. The trial consisted of a 12-month intervention and 12-month observation period. For the intervention, participants were randomized to either a moderate-volume exercise group (150 min/week) or a high-volume exercise group (300 min/week). Participants in this study were 334 inactive postmenopausal women who had been followed-up to 24 months. The primary outcome for this study was 24-month change in total body fat using dual energy X-ray absorptiometry scans. Other measures included weight, waist and hip circumferences, subcutaneous and intra-abdominal fat from computed tomography scans, and lean mass. Researchers were blinded to randomization group when measuring body fat.

RESULTS

Both groups self-reported ∼180 minutes/week moderate-vigorous activity at 24 months. No statistically significant difference was found in total body fat at 24 months between the two groups. Statistically significant effects (comparing high versus moderate groups) were found for BMI (least-square mean change (95% CI): -0.66 (-0.97, -0.36) versus -0.25 (-0.55, 0.05) kg/m², P=0.04), waist-to-hip ratio (-0.033 (-0.040, -0.026) versus -0.023 (-0.030, -0.016), P=0.05), and subcutaneous abdominal fat area (-32.18 (-39.30, -25.06) versus -22.20 (-29.34, -15.05) cm², P=0.04).

CONCLUSION

Prescribing 300 versus 150 minutes/week of exercise to inactive postmenopausal women resulted in some long-term greater decreases in measures of body composition but no overall differences in total body fat loss. This trail is registered with NCT01435005.

Sedentary time and postmenopausal breast cancer incidence

PURPOSE

The objective of this study was to evaluate the prospective association between sedentary time and postmenopausal breast cancer incidence, and whether associations differ by race/ethnicity, physical activity levels, and body measurements.

METHODS

The Women's Health Initiative Observational Study is a prospective cohort among women ages 50-79 years at baseline (1994-1998) (analytic cohort = 70,233). Baseline questionnaire data were used to estimate time spent sitting and total sedentary time. Associations between time spent sitting and invasive breast cancer incidence overall (n = 4,115 cases through September 2015), and by hormone receptor subtypes, were investigated using Cox proportional hazards regression. Analyses were replicated stratified by race/ethnicity, body measurements, and physical activity.

RESULTS

Among women in this study, 34.5% reported ≤ 5 h/day sitting, 40.9% reported 6-9 h/day and 24.7% reported ≥ 10 h/day. Time spent sitting (≥ 10 vs. ≤5 h/day adjusted HR = 1.00, 95% CI 0.92-1.09) was not associated with breast cancer incidence, regardless of hormone receptor subtype. Associations did not differ by race/ethnicity, physical activity, or body measurements.

CONCLUSIONS

Results from this study do not support an association between sedentary time and breast cancer incidence.

Effects of potentially modifiable risk factors on the health of adults in the Eastern Province of KSA

Objectives

The purpose of this study was to investigate the association between selected major modifiable risk factors including life style habits, household income and smoking on health.

Methods

This cross-sectional study was conducted during 2015-2016 among 104 healthy men aged 38 ± 8 years. The data were collected using a self-administered questionnaire that enquired about clinical information about blood pressure and body mass index. Venous blood samples were taken to assess the fasting blood glucose (FBG), lipid profile, high density lipoprotein and triglyceride.

Results

Current smoking status and consumed energy drinks were significantly positive risk factors for increased systolic blood pressure and FBG, respectively. Participants with monthly income of more than 10,000 Saudi Riyals showed significantly lower diastolic pressure than those with lower income. However, there was a significant decrease in body weight among those who consumed vegetables.

Conclusion

This study highlights the effect of major modifiable risk factors on health. There is a great need for improving and enhancing a healthy lifestyle behaviour.

Exploring parents' screen-viewing behaviours and sedentary time in association with their attitudes toward their young child's screen-viewing

Sedentary time and screen-viewing (SV) are associated with chronic disease risk in adults. Parent and child sedentary time and SV are associated. Parents influence children's SV through parenting styles and role modelling. Understanding whether parents' attitudes toward child SV are associated with their own SV and sedentary time will aid development of family interventions to reduce sedentary behaviours. Cross-sectional data with 809 parents from Bristol, UK were collected in 2012–2013 and analysed in 2016. Parental total sedentary time was derived from accelerometer data. Parents self-reported daily television viewing, use of computers, games consoles, and smartphone/tablets (none, 1–59 min, 1–2 h, > 2 h) and attitudes toward child SV. Adjusted linear and logistic regression models were used to examine associations, separately for weekdays and weekend days. Having negative attitudes toward child SV was associated with lower weekend sedentary time (Coeff: − 6.41 [95% CI: − 12.37 to − 0.45] min/day). Limiting behaviours and having negative attitudes toward child SV were associated with lower weekday television viewing (OR: 0.72 [0.57–0.90] and 0.57 [0.47–0.70] respectively), weekend television viewing (0.75 [0.59–0.95] and 0.61 [0.50–0.75]), and weekend computer use (0.73 [0.58–0.92] and 0.80 [0.66–0.97]). Negative attitudes were also associated with lower smartphone use on weekdays (0.70 [0.57–0.85]) and weekends (0.70 [0.58–0.86]). Parent self-efficacy for limiting child SV and setting SV rules were not associated with sedentary time or SV. Reporting negative attitudes toward child SV was associated with lower accelerometer-assessed weekend total sedentary time and self-reported SV behaviours, while limiting child SV was also associated with lower self-reported SV.

•

Limiting child SV is associated with lower TV viewing and computer use in parents.

•

Having negative attitudes toward child SV is associated with lower SV in parents.

•

Negative attitudes toward child SV are associated with lower parent sedentary time.

•

Self-efficacy for limiting SV is not associated with parents' SV & sedentary time.

•

Setting SV rules for children is not associated with parents' SV & sedentary time.

Longitudinal associations of away-from-home eating, snacking, screen time, and physical activity behaviors with cardiometabolic risk factors among Chinese children and their parents

Background: Little is known about intergenerational differences in associations of urbanization-related lifestyle behaviors with cardiometabolic risk factors in children and their parents in rapidly urbanizing China.Objective: We tested the intergenerational differences in longitudinal associations of away-from-home eating, snacking, screen time, and leisure-time sports with high waist-to-height ratio (WHtR), elevated blood pressure (BP), elevated glycated hemoglobin (HbA1c), and elevated C-reactive protein (CRP) among Chinese children and their parents.Design: We studied children enrolled in the longitudinal China Health and Nutrition Survey (1991-2009, 7 surveys) aged 7-17 y in ≥2 surveys (average follow-up: 2.3 surveys out of a possible 4 surveys with the age restriction; n = 3875, including 1175 siblings) and their parents (2947 mothers, 2632 fathers) living in the same household. We used 3 consecutive interviewer-administered 24-h dietary recalls to derive a 3-d average for away-from-home eating (nonconsumer, >0 and <1 meal/d, or ≥1 meals/d) and consumption of fruit or vegetable snacks (any or none) and other snacks (any or none) and a self-reported 7-d physical activity recall for screen time (≤1, >1 and ≤2, or >2 h/d) and leisure-time sports (any or none). Random-effects logistic regression was used to examine the associations of lagged (average: 3 y) behaviors with cardiometabolic risk factors (WHtR, BP, HbA1c, and CRP).Results: We detected intergenerational differences in associations between lagged behaviors and risk factors (P-interaction < 0.1). Generation-specific models showed that lagged away-from-home eating of ≥1 meal/d (compared with none) was negatively associated with parents' high WHtR (OR: 0.68; 95% CI: 0.53, 0.88) but positively associated with children's high WHtR (OR: 1.46; 95% CI: 1.01, 2.12). Lagged fruit and vegetable snack consumption was negatively related to parents' (OR: 0.76; 95% CI: 0.59, 0.97) and children's (OR: 0.58; 95% CI: 0.33, 1.00) high WHtR. Lagged screen time (>2 compared with ≤1 h/d) was positively associated with parents' (OR: 2.58; 95% CI: 1.56, 4.28) and children's high WHtR (OR: 2.26; 95% CI: 1.06, 4.83).Conclusion: Parent-offspring differences in associations between lifestyle behaviors and cardiometabolic risk factors provide insight into intergenerational differences in cardiometabolic risk with urbanization.

Low physical activity, high television viewing and poor sleep duration cluster in overweight and obese adults; a cross-sectional study of 398,984 participants from the UK Biobank

BACKGROUND

An unhealthy lifestyle is one of the greatest contributors to obesity. A number of behaviours are linked with obesity, but are often measured separately. The UK Biobank cohort of >500,000 participants allows us to explore these behaviours simultaneously. We therefore aimed to compare physical activity, television (TV) viewing and sleep duration across body mass index (BMI) categories in a large sample of UK adults.

METHODS

UK Biobank participants were recruited and baseline measures were taken between 2007 and 2010 and data analysis was performed in 2015. BMI was measured objectively using trained staff. Self-report questionnaires were used to measure lifestyle behaviours including the international physical activity questionnaire (IPAQ-short form) for physical activity. During data analysis, six groups were defined based on BMI; 'Underweight' (n = 2026), 'Normal weight' (n = 132,372), 'Overweight (n = 171,030), 'Obese I' (n = 67,903), 'Obese II' (n = 18,653) and 'Obese III' (n = 7000). The odds of reporting unhealthy lifestyle behaviours (low physical activity, high TV viewing or poor sleep duration) were compared across BMI groups using logistic regression analysis.

RESULTS

Overweight and obese adults were more likely to report low levels of physical activity (≤967.5 MET.mins/wk) ('Overweight'-OR [95% CI]: 1.23 [1.20 to 1.26], 'Obese I' 1.66 [1.61-1.71], 'Obese II' 2.21 [2.12-2.30], and 'Obese III' 3.13 [2.95 to 3.23]) compared to 'Normal weight' adults. The odds of reporting high TV viewing (3 h/day) was greater in 'Overweight' (1.52 [1.48 to 1.55]) and obese adults ('Obese I' 2.06 [2.00-2.12], 'Obese II' 2.69 [2.58-2.80], 'Obese III' 3.26 [3.07 to 3.47]), and poor sleep duration (<7, >8 h/night) was higher in 'Overweight' (1.09 [1.07 to 1.12]) and obese adults ('Obese I' 1.31 [1.27-1.34], 'Obese II' 1.50 [1.44-1.56], 'Obese III' (1.78 [1.68 to 1.89]) compared to the 'Normal weight' group. These lifestyle behaviours were clustered, the odds of reporting simultaneous low physical activity, high TV viewing and poor sleep (unhealthy behavioural phenotype) was higher than reporting these behaviours independently, in overweight and obese groups. 'Obese III' adults were almost six times more likely (5.47 [4.96 to 6.05]) to report an unhealthy behavioural phenotype compared to the 'Normal weight' group.

CONCLUSIONS

Overweight and obese adults report low levels of physical activity, high TV viewing and poor sleep duration. These behaviours seem to cluster and collectively expose individuals to greater risk of obesity. Multiple lifestyle behaviours should be targeted in future interventions.

Physical Activity, Television Viewing Time, and 12-Year Changes in Waist Circumference

Purpose

Both moderate-to-vigorous physical activity (MVPA) and sedentary behavior can be associated with adult adiposity. Much of the relevant evidence is from cross-sectional studies or from prospective studies with relevant exposure measures at a single time point before weight gain or incident obesity. This study examined whether changes in MVPA and television (TV) viewing time are associated with subsequent changes in waist circumference, using data from three separate observation points in a large population-based prospective study of Australian adults.

Methods

Data were obtained from the Australian Diabetes, Obesity, and Lifestyle study collected in 1999–2000 (baseline), 2004–2005 (wave 2), and 2011–2012 (wave 3). The study sample consisted of adults age 25 to 74 yr at baseline who also attended site measurement at three time points (n = 3261). Multilevel linear regression analysis examined associations of initial 5-yr changes in MVPA and TV viewing time (from baseline to wave 2) with 12-yr change in waist circumference (from baseline to wave 3), adjusting for well-known confounders.

Results

As categorical predictors, increases in MVPA significantly attenuated increases in waist circumference (P for trend < 0.001). TV viewing time change was not significantly associated with changes in waist circumference (P for trend = 0.06). Combined categories of MVPA and TV viewing time changes were predictive of waist circumference increases; compared with those who increased MVPA and reduced TV viewing time, those who reduced MVPA and increased TV viewing time had a 2-cm greater increase in waist circumference (P = 0.001).

Conclusion

Decreasing MVPA emerged as a significant predictor of increases in waist circumference. Increasing TV viewing time was also influential, but its impact was much weaker than MVPA.

Reallocating Time to Sleep, Sedentary Time, or Physical Activity: Associations with Waist Circumference and Body Mass Index in Breast Cancer Survivors

BACKGROUND

Moderate-to-vigorous intensity physical activity (MVPA) is inversely associated with waist circumference and body mass index (BMI) among breast cancer survivors. Limited research has focused on behaviors that account for larger portions of the day [sleep, sedentary time, and light-intensity physical activity (LPA)]. We investigated the interdependent associations of self-reported sleep, objectively assessed prolonged and short bouts of sedentary time, total LPA, and total MVPA with waist circumference and BMI.

METHODS

A cross-sectional sample of breast cancer survivors (N = 256, mean age = 60 years; mean time since diagnosis = 3 years) wore an Actigraph GT3X+ accelerometer during waking hours for 7 days. Participants completed the Pittsburgh Sleep Quality Index and self-reported their waist circumference, height, and weight. An isotemporal substitution approach was used in linear regression models to explore the associations of reallocating time to sleep, sedentary and active behaviors on waist circumference, and BMI, after adjusting for potential confounders.

RESULTS

Reallocating 30 minutes to MVPA was significantly associated with lower waist circumference when allocated from sleep (-2.50 cm), prolonged sedentary time (-2.51 cm), or LPA (-2.71 cm). Reallocating 30 minutes of prolonged sedentary time to nonprolonged sedentary time was significantly associated with lower waist circumference (-0.94 cm). Similar results were observed for BMI.

CONCLUSIONS

Reallocating 30 minutes to MVPA was associated with significantly lower waist circumference and BMI, as was reallocating 30 minutes of prolonged sedentary time to 30 minutes of nonprolonged sedentary time.

IMPACT

Increasing MVPA levels and decreasing time spent in prolonged, unbroken sedentary bouts may be avenues for improving body composition in this population. Cancer Epidemiol Biomarkers Prev; 26(2); 254-60. ©2016 AACR.

Impact of sit-stand desks at work on energy expenditure and sedentary time: protocol for a feasibility study

BACKGROUND

Prolonged sitting, an independent risk factor for disease development and premature mortality, is increasing in prevalence in high- and middle-income countries, with no signs of abating. Adults in such countries spend the largest proportion of their day in sedentary behaviour, most of which is accumulated at work. One promising method for reducing workplace sitting is the use of sit-stand desks. However, key uncertainties remain about this intervention, related to the quality of existing studies and a lack of focus on key outcomes, including energy expenditure. We are planning a randomised controlled trial to assess the impact of sit-stand desks at work on energy expenditure and sitting time in the short and longer term. To reduce the uncertainties related to the design of this trial, we propose a preliminary study to assess the feasibility and acceptability of the recruitment, allocation, measurement, retention and intervention procedures.

METHODS

Five hundred office-based employees from two companies in Cambridge, UK, will complete a survey to assess their interest in participating in a trial on the use of sit-stand desks at work. The workspaces of 100 of those interested in participating will be assessed for sit-stand desk installation suitability, and 20 participants will be randomised to either the use of sit-stand desks at work for 3 months or a waiting list control group. Energy expenditure and sitting time, measured via Actiheart and activPAL monitors, respectively, as well as cardio-metabolic and anthropometric outcomes and other outcomes relating to health and work performance, will be assessed in 10 randomly selected participants. All participants will also be interviewed about their experience of using the desks and participating in the study.

DISCUSSION

The findings are expected to inform the design of a trial assessing the impact of sit-stand desks at work on short and longer term workplace sitting, taking into account their impact on energy expenditure and the extent to which their use has compensation effects outside the workplace. The findings from such a trial are expected to inform discussions regarding the potential of sit-stand desks at work to alleviate the harm to cardio-metabolic health arising from prolonged sitting.

TRIAL REGISTRATION

ISRCTN44827407.

What Is the Effect on Obesity Indicators from Replacing Prolonged Sedentary Time with Brief Sedentary Bouts, Standing and Different Types of Physical Activity during Working Days? A Cross-Sectional Accelerometer-Based Study among Blue-Collar Workers

Introduction

The aim of the study was to investigate if (a) substituting total sedentary time or long sedentary bouts with standing or various types of physical activity and (b) substituting long sedentary bouts with brief sedentary bouts; is associated with obesity indicators using a cross sectional isotemporal substitution approach among blue-collar workers.

Methods

A total of 692 workers from transportation, manufacturing and cleaning sectors wore an Actigraph GT3X+ accelerometer on the thigh for 1–4 working days. The sedentary (sit and lie), standing, walking, and moderate to vigorous physical activity (MVPA) time on working days was computed using validated Acti4 software. The total sedentary time and uninterrupted sedentary time spent in brief (≤5 mins), moderate (>5 and ≤30 mins), and long (>30mins) bouts, were determined for the whole day and during work and non-work time separately. The obesity indicators, BMI (kg/m²), waist circumference (cm) and fat percentage were objectively measured. Isotemporal substitution modelling was utilized to determine the linear association with obesity indicators of replacing 30 min of total sedentary time or long sedentary bouts with standing, walking or MVPA and separately replacing 30 min of long sedentary bouts with brief sedentary bouts.

Results

Workers [mean (standard deviation, SD); age = 45.1 (9.9) years, BMI = 27.5 (4.9) kg/m², %BF = 29.6 (9.5), waist circumference = 94.4 (13.0) cm] sat for 2.4 hours (~32% of the measured time, SD = 1.8 hours) across the day during work period and 5.5 hours (~62% of the measured time, SD = 1.5 hours) during non-work period. Most of the sedentary time was accrued in moderate bouts [work = 1.40 (SD = 1.09) hours] during work and in long bouts during non-work [2.7 (SD = 1.4) hours], while least in long sedentary bouts during work [work = 0.5 (SD = 0.9)] and in brief sedentary bouts [0.5 hours (SD = 0.3)] during non-work. Significant associations with all obesity indicators were found when 30 min of total sedentary time or long sedentary bouts were replaced with standing time (~1–2% lower) or MVPA (~4–9% lower) during whole day, work, and non-work periods. The exception was that a statistically significant association was not observed with any obesity indicator when replacing total sedentary time or long sedentary bouts with standing time during the work period. Significant beneficial associations were found when replacing the long sedentary bouts with brief sedentary bouts (~3–5% lower) during all domains.

Conclusion

Replacing total sedentary time and long sedentary bouts, respectively, not only with MVPA but also standing time appears to be beneficially associated with obesity indicators among blue-collar workers. Additionally, replacing long sedentary bouts with brief sedentary bouts was also beneficially associated with obesity indicators. Studies using prospective design are needed to confirm the findings.

Associations of objectively assessed physical activity and sedentary time with all-cause mortality in US adults: the NHANES study

Background

Sedentary behavior is related to increased mortality risk. Whether such elevated risk can be offset by enhanced physical activity has not been examined using accelerometry data.

Materials and Methods

We examined the relations of sedentary time and physical activity to mortality from any cause using accelerometry data among 1,677 women and men aged 50 years or older from the National Health and Nutrition Examination Survey (NHANES) 2003–2004 cycle with follow-up through December 31, 2006.

Results

During an average follow-up of 34.67 months and 4,845.42 person-years, 112 deaths occurred. In multivariate Cox proportional hazard models, greater sedentary time (≥ median of 8.60 hours/day) was associated with increased risk of mortality from any cause (relative risk (RR) = 2.03; 95% confidence interval (CI) = 1.09-3.81). Low level of moderate to vigorous physical activity (< median of 6.60 minutes/day) was also related to enhanced all-cause mortality risk (RR = 3.30; 95% CI = 1.33-8.17). In combined analyses, greater time spent sedentary and low levels of moderate to vigorous physical activity predicted a substantially elevated all-cause mortality risk. As compared with the combination of a low sedentary level and a high level of moderate to vigorous physical activity, the risks of mortality from all causes were 4.38 (95% CI = 1.26-15.16) for low levels of both sedentary time and physical activity, 2.79 (95% CI = 0.77-10.12) for greater time spent sedentary and high physical activity level, and 7.79 (95% CI = 2.26-26.82) for greater time spent sedentary and low physical activity level. The interaction term between sedentary time and moderate to vigorous physical activity was not statistically significant (p = 0.508).

Conclusions

Both high levels of sedentary time and low levels of moderate to vigorous physical activity are strong and independent predictors of early death from any cause. Whether a high physical activity level removes the increased risk of all-cause mortality related to sedentariness requires further investigation.

Typing performance and body discomfort among overweight and obese office workers: A pilot study of keyboard modification

Obesity in the workplace is associated with loss of productivity, high medical care expenses, and increased rates of work-related injuries and illness. Thus, effective, low-cost interventions are needed to accommodate the size of today's obese office worker while alleviating potential physical harm associated with musculoskeletal disorders. Utilizing a sample of 22 overweight and obese office workers, this pilot study assessed the impact of introducing an alternative, more ergonomically-sound keyboard on perceptions about design, acceptability, and usability; self-reported body discomfort; and typing productivity. Data were collected using self-reported questionnaires and objective typing tests administered before and after the intervention. The intervention duration was six weeks. After switching from their standard work keyboard to an alternative keyboard, all participants reported significant decreases in lower back discomfort (t = 2.14, P = 0.044); although obese participants reported significant decreases in both upper (t = 2.46, P = 0.032) and lower (t = 2.39, P = 0.036) back discomfort. No significant changes were observed in overall typing performance scores from baseline to follow-up. Findings suggest that such interventions may be introduced into the workforce with positive gains for workers without reducing short-term worker productivity.

Sedentary behaviour and diet across the lifespan: an updated systematic review

BACKGROUND

Sedentary behaviour and its association with dietary intake in young people and adults are important topics and were systematically reviewed in 2011. There is a need to update this evidence given the changing nature of sedentary behaviour and continued interest in this field. This review aims to assist researchers in better interpreting the diversity of findings concerning sedentary behaviour and weight status.

OBJECTIVE

To provide an update of the associations between sedentary behaviour and dietary intake across the lifespan.

METHODS

Electronic databases searched were MEDLINE, PsychInfo, Cochrane Library, Web of Science and Science Direct for publications between January 2010 and October 2013, thus updating a previous review. Included were observational studies assessing an association between at least one sedentary behaviour and at least one aspect of dietary intake in preschool children (<5 years), school-aged children (6-11 years), adolescents (12-18 years) and adults (>18 years).

RESULTS

27 papers met inclusion criteria (preschool k=3, school-aged children k=9, adolescents k=15, adults k=3). For all three groups of young people, trends were evident for higher levels of sedentary behaviour, especially TV viewing, to be associated with a less healthful diet, such as less fruit and vegetable and greater consumption of energy-dense snacks and sugar sweetened beverages. Data for the three studies with adults were less conclusive.

CONCLUSIONS

Sedentary behaviour continues to be associated with unhealthy diet in young people in mostly cross-sectional studies. More studies utilising a prospective design are needed to corroborate findings and more studies are needed with adults.

Associations of physical activity and sedentary behavior with regional fat deposition

INTRODUCTION

Increased sedentary behavior predicts greater cardiovascular morbidity and mortality and does so independently of physical activity (PA). This association is only partially explained by body mass index (BMI) and overall body fat, suggesting mechanisms besides general increased adiposity. The purpose of this study was to explore associations of self-reported leisure PA and sitting time with regional fat depositions and abdominal muscle among community-dwelling older adults.

METHODS

Participants were 539 diverse adults (mean age = 65 yr) who completed a study visit in 2001-2002. Areas of pericardial, intrathoracic, subcutaneous, visceral, and intermuscular fat, as well as abdominal muscle, were measured using computed tomography. Leisure PA and sitting hours were entered simultaneously into multivariate regression models to determine associations with muscle and fat areas.

RESULTS

After adjusting for demographics, smoking, diabetes, hypertension, triglycerides, and cholesterol, greater PA was associated with less intrathoracic, visceral, subcutaneous, and intermuscular fat (for all P < 0.05), while greater sedentary time was associated with greater pericardial and intrathoracic fat (for both P < 0.05). After further adjusting for BMI, each hour of weekly PA was associated with 1.85 cm less visceral fat (P < 0.01) but was not associated with other fat depositions. Conversely, each hour of daily sitting was associated with 2.39 cm more pericardial fat (P < 0.05) but was not associated with any other fat depositions. There were no associations with abdominal muscle area. Adjusting for common inflammatory markers had little effect. Associations between fat and PA were stronger for men.

CONCLUSIONS

Sitting and PA have distinct associations with regional fat deposition in older adults. The association between sitting and pericardial fat could partially explain the link between sitting and coronary heart disease.

Modifying effect of obesity on the association between sitting and incident diabetes in post-menopausal women

OBJECTIVE

To evaluate the association between self-reported daily sitting time and the incidence of type 2 diabetes in a cohort of postmenopausal women.

METHODS

Women (N=88,829) without diagnosed diabetes reported the number of hours spent sitting over a typical day. Incident cases of diabetes were identified annually by self-reported initiation of using oral medications or insulin for diabetes > 14.4 years follow-up.

RESULTS

Each hour of sitting time was positively associated with increased risk of diabetes [risk ratio (RR): 1.05; 95% confidence interval (CI): 1.02-1.08]. However, sitting time was only positively associated with incident diabetes in obese women. Obese women reporting sitting 8-11 (RR: 1.08; 95% CI 1.0-1.1), 12-15 (OR: 1.13; 95% CI 1.0-1.2), and ≥16 hours (OR: 1.25; 95% CI 1.0-1.5) hours per day had an increased risk of diabetes compared to women sitting ≤7 hours per day. These associations were adjusted for demographics, health conditions, behaviors (smoking, diet, and alcohol intake), and family history of diabetes. Time performing moderate to vigorous intensity physical activity did not modify these associations.

CONCLUSIONS

Time spent sitting was independently associated with increased risk of diabetes diagnosis among obese women-a population already at high risk of the disease.

Energy balance and metabolism after cancer treatment

Unfavorable physiological, biological, and behavioral alterations during and following treatment for cancer may lead to chronic energy imbalance predisposing to a myriad of deleterious health conditions including obesity, dyslipidemia, and the metabolic syndrome. In addition to the cardiovascular and musculoskeletal effects of these conditions, energy imbalance and metabolic changes after cancer treatment can also affect cancer-related morbidity and mortality. To this end, lifestyle interventions such as diet and physical activity are especially relevant to mitigate the deleterious impact of chronic energy imbalance in cancer survivors.

Association of sedentary behaviour with colon and rectal cancer: a meta-analysis of observational studies

BACKGROUND

Sedentary behaviour is ubiquitous in modern society. Emerging studies have focused on the health consequences of sedentary behaviour, including colorectal cancer, but whether sedentary behaviour is associated with the risks of colon and rectal cancer remains unclear. No systematic reviews have applied quantitative techniques to independently compute summary risk estimates. We aimed to conduct a meta-analysis to investigate this issue.

METHODS

We searched PubMed, Embase, and Google Scholar databases up to May 2013 to identify cohort and case-control studies that evaluated the association between sedentary behaviour and colon or rectal cancer. A random-effect model was used to pool the results of included studies. Publication bias was assessed by using Begg's funnel plot.

RESULTS

Twenty-three studies with 63 reports were included in our meta-analysis. These groups included 4,324,462 participants (27,231 colon cancer cases and 13,813 rectal cancer cases). Sedentary behaviour was significantly associated with colon cancer (relative risk (RR): 1.30, 95% confidence interval (CI): 1.22-1.39) but did not have a statistically significant association with rectal cancer (RR 1.05, 95% CI, 0.98-1.13). Subgroup analyses suggested that the odds ratio (OR) of colon cancer was 1.46 (95% CI: 1.22-1.68) in the case-control studies, and the RR was 1.27 (95% CI: 1.18-1.36) in the cohort studies, the OR of rectal cancer was 1.06 (95% CI: 0.85-1.33) in the case-control studies, and the RR was 1.06 (95% CI, 1.01-1.12) in the cohort studies.

CONCLUSION

Sedentary behaviour is associated with an increased risk of colon cancer. Subgroup analyses suggest a positive association between sedentary behaviour and risk of rectal cancer in cohort studies. Reducing sedentary behaviour is potentially important for the prevention of colorectal cancer.

Sit-stand desks in call centres: associations of use and ergonomics awareness with sedentary behavior

OBJECTIVE

To investigate whether or not use of sit-stand desks and awareness of the importance of postural variation and breaks are associated with the pattern of sedentary behavior in office workers.

METHOD

The data came from a cross-sectional observation study of Swedish call centre workers. Inclinometers recorded 'seated' or 'standing/walking' episodes of 131 operators over a full work shift. Differences in sedentary behavior based on desk type and awareness of the importance of posture variation and breaks were assessed by non-parametric analyses.

RESULTS

90 (68.7%) operators worked at a sit-stand desk. Working at a sit-stand desk, as opposed to a sit desk, was associated with less time seated (78.5 vs 83.8%, p = 0.010), and less time taken to accumulate 5 min of standing/walking (36.2 vs 46.3 min, p = 0.022), but no significant difference to sitting episode length or the number of switches between sitting and standing/walking per hour. Ergonomics awareness was not associated with any sedentary pattern variable among those using a sit-stand desk.

CONCLUSION

Use of sit-stand desks was associated with better sedentary behavior in call centre workers, however ergonomics awareness did not enhance the effect.

Sedentary behaviours in mid-adulthood and subsequent body mass index

OBJECTIVES

It is unclear whether sedentary behaviour, and the domain in which it occurs, is related to body mass index (BMI) change. We aim to elucidate whether sedentary behaviour is prospectively related to BMI change using markers from three domains (leisure, work and commuting).

METHODS

Among employed 1958 British birth cohort members (n = 6,562), we analysed whether TV-viewing, work sitting (six categories: 0 h/d to >4 h/d) and motorised commuting (at 45 y) were related to BMI (at 45 y and 50 y) and BMI change 45-50 y, after adjusting for lifestyle and socioeconomic factors.

RESULTS

Per category higher TV-viewing, 45 y and 50 y BMI were higher by 0.69 kg/m(2) (95% CI: 0.59,0.80) and 0.75 kg/m(2) (0.64,0.86) respectively. A category higher TV-viewing was associated with 0.11 kg/m(2) (0.06,0.17) increased BMI 45-50 y, attenuating to 0.06 kg/m(2) (0.01,0.12) after adjustment. There was no trend for work sitting with 45 y or 50 y BMI, nor, after adjustment, for BMI change. However, those sitting 2-3 h/d had greater BMI gain by 0.33 kg/m(2) (0.10,0.56) compared to those sitting 0-1 h/d. Associations between TV-viewing and BMI change were independent of work sitting. Motorised commuting was associated with 45 y, but not 50 y BMI or change.

CONCLUSIONS

TV-viewing is associated with BMI gain in mid-adulthood; evidence is weaker for other sedentary behaviours.

Sedentary behavior, physical activity, and likelihood of breast cancer among Black and White women: a report from the Southern Community Cohort Study

Increased physical activity has been shown to be protective for breast cancer although few studies have examined this association in Black women. In addition, limited evidence to date indicates that sedentary behavior may be an independent risk factor for breast cancer. We examined sedentary behavior and physical activity in relation to subsequent incident breast cancer in a nested case-control study within 546 cases (374 among Black women) and 2,184 matched controls enrolled in the Southern Community Cohort Study. Sedentary and physically active behaviors were assessed via self-report at study baseline (2002-2009) using a validated physical activity questionnaire. Conditional logistic regression was used to estimate mutually adjusted ORs and corresponding 95% confidence intervals (CI) for quartiles of sedentary and physical activity measures in relation to breast cancer risk. Being in the highest versus lowest quartile of total sedentary behavior (≥ 12 vs. <5.5 h/d) was associated with increased odds of breast cancer among White women [OR, 1.94 (95% CI, 1.01-3.70); P trend = 0.1] but not Black women [OR, 1.23 (95% CI, 0.82-1.83); P trend = 0.6] after adjustment for physical activity. After adjustment for sedentary activity, greater physical activity was associated with reduced odds for breast cancer among White women (P trend = 0.03) only. In conclusion, independent of one another, sedentary behavior and physical activity are risk factors for breast cancer among White women. Differences in these associations between Black and White women require further investigation. Reducing sedentary behavior and increasing physical activity are potentially independent targets for breast cancer prevention interventions.

Physical activity in obesity and metabolic syndrome

Biological aging is typically associated with a progressive increase in body fat mass and a loss of lean body mass. Owing to the metabolic consequences of reduced muscle mass, it is understood that normal aging and/or decreased physical activity may lead to a higher prevalence of metabolic disorders. Lifestyle modification, specifically changes in diet, physical activity, and exercise, is considered the cornerstone of obesity management. However, for most overweight people it is difficult to lose weight permanently through diet or exercise. Thus, prevention of weight gain is thought to be more effective than weight loss in reducing obesity rates. A key question is whether physical activity can extenuate age-related weight gain and promote metabolic health in adults. Current guidelines suggest that adults should accumulate about 60 minutes of moderate-intensity physical activity daily to prevent unhealthy weight gain. Because evidence suggests that resistance training may promote a negative energy balance and may change body fat distribution, it is possible that an increase in muscle mass after resistance training may be a key mediator leading to better metabolic control.

Towards integrated physical activity profiling

Recently, there has been some discussion of whether it is possible to score highly in one dimension of physical activity behaviour (e.g., moderate intensity exercise) whilst also scoring poorly in another (e.g., sedentary time). Interestingly, direct empirical observations to support these proposals are lacking. New technologies now enable the capture of physical activity thermogenesis on a minute-by-minute basis and over a sustained period. We used one of the best available technologies to explore whether individuals can score differently in various physiologically-important physical activity dimensions. We determined minute-by-minute physical activity energy expenditure over 7 days in 100 men aged 28 ± 9 years. We used combined accelerometry and heart rate with branched equation modelling to estimate energy expenditure and extracted data for key physical activity outcomes and descriptors. Although some physical activity outcomes were tightly correlated, the attainment of one threshold for a given physical activity dimension did not automatically predict how well an individual scored in another dimension (with bivariate correlations ranging from 0.05 to 0.96). In one illustrative example of this heterogeneity, although 41 men showed a relatively low Physical Activity Level (total energy expenditure/resting energy expenditure ≤ 1.75), only 17% (n=7) of these men showed consistently low physical activity across other dimensions (moderate intensity activity, vigorous intensity activity, and sedentary time). Thus, physical activity is highly heterogeneous and there is no single outcome measure that captures all the relevant information about a given individual. We propose that future studies need to capture (rather than ignore) the different physiologically-important dimensions of physical activity via generation of integrated, multidimensional physical activity 'profiles'.

Sitting behavior and obesity: evidence from the Whitehall II study

BACKGROUND

Prospective studies report associations between indicators of time spent sitting and obesity risk. Most studies use a single indicator of sedentary behavior and are unable to clearly identify whether sedentary behavior is a cause or a consequence of obesity.

PURPOSE

To investigate cross-sectional and prospective associations between multiple sitting time indicators and obesity and examine the possibility of reverse causality.

METHODS

Using data from the Whitehall II cohort, multiple logistic models were fitted to examine associations between prevalent obesity (BMI ≥30) at Phase 5 (1997-1999), and incident obesity between Phases 5 and 7 (2003-2004) across four levels of five sitting exposures (work sitting, TV viewing, non-TV leisure-time sitting, leisure-time sitting, and total sitting). Using obesity data from three prior phases (1985-1988, 1991-1993; and recalled weight at age 25 years), linear regression models were fitted to examine the association between prior obesity and sitting time at Phase 5. Analyses were conducted in 2012.

RESULTS

None of the sitting exposures were associated with obesity either cross-sectionally or prospectively. Obesity at one previous measurement phase was associated with a 2.43-hour/week (95% CI=0.07, 4.78) increase in TV viewing; obesity at three previous phases was associated with a 7.42-hour/week (95% CI=2.7, 12.46) increase in TV-viewing hours/week at Phase 5.

CONCLUSIONS

Sitting time was not associated with obesity cross-sectionally or prospectively. Prior obesity was prospectively associated with time spent watching TV per week but not other types of sitting.

Physical activity and body mass: changes in younger versus older postmenopausal women

PURPOSE

The study's purpose was to investigate the relationship of sedentary (≤ 100 MET · min · wk(-1)), low (>100-500 MET · min · wk(-1)), moderate (>500-1200 MET · min · wk(-1)), and high (>1200 MET · min · wk(-1)) habitual physical activity with body weight, body mass index, and measures of fat distribution (waist-to-hip ratio) in postmenopausal women by age decades.

METHODS

A prospective cohort study of 58,610 postmenopausal women age 50-79 yr weighed annually during 8 yr at one of 40 US clinical centers was analyzed to determine the relationship of high versus low habitual physical activity with changes in body weight and fat distribution by age group.

RESULTS

Among women age 50-59 yr, there was significant weight loss in those expending >500-1200 MET · min · wk(-1) (coefficient = -0.30, 95% confidence interval = -0.53 to -0.07) compared with the group expending ≤ 100 MET · min · wk(-1). Among women age 70-79 yr, higher physical activity was associated with less weight loss (coefficient = 0.34, 95% confidence interval = 0.04-0.63). Age at baseline significantly modified the association between physical activity and total weight change, whereas baseline body mass index did not.

CONCLUSIONS

High habitual physical activity is associated with less weight gain in younger postmenopausal women and less weight loss in older postmenopausal women. These findings suggest that promoting physical activity among postmenopausal women may be important for managing body weight changes that accompany aging.

Adult sedentary behavior: a systematic review

CONTEXT

While the health benefits of meeting moderate/vigorous-intensity physical activity (MVPA) guidelines have been well established, the health risks of sedentary behavior, independent of meeting MVPA guidelines, are becoming evident. Sedentary behavior may require different interventions, based on correlates that differ from MVPA. The current review aimed to collect and appraise the current literature on correlates of sedentary behaviors among adults.

EVIDENCE ACQUISITION

Papers were considered eligible if they were published in English-language peer-reviewed journals and examined correlates of sedentary behaviors. Literature searches were conducted in August 2011 among ten search engines yielding 3691 potentially relevant records; of these, 109 papers (82 independent samples) passed eligibility criteria.

EVIDENCE SYNTHESIS

Articles included were published between 1982 and 2011, with sample sizes ranging from 39 to 123,216. Eighty-three were cross-sectional, 24 followed a prospective design, one was experimental baseline data, and one was cohort design. Sedentary behavior was primarily measured as TV viewing or computer use, followed by analysis of a more omnibus assessment of time spent sitting. Evidence was present for sedentary behavior and correlates of education, age, employment status, gender, BMI, income, smoking status, MVPA, attitudes, and depressive symptoms/quality of life. Notable differences by specific sedentary behaviors were present that aided in the explanation of findings.

CONCLUSIONS

Results point to the high specificity of various sedentary behaviors (e.g., TV viewing vs sitting and socializing), suggesting that the research domain is complex and cannot be considered the simple absence of MVPA. Several sociodemographic and health factors appear reliably linked to sedentary behavior, yet there is an obvious absence of research focused on cognitive, social, and environmental factors that could be of use in anti-sedentary behavior interventions.

Preventing weight gain through exercise and physical activity in the elderly: a systematic review

This review examines the role of exercise and physical activity for preventing weight gain in older people. A structured search using MeSH-vocabulary and Title/Abstract-searches was conducted in PubMed for January 2000 to June 2011, identifying weight gain and exercise or physical activity as study topics, and aged adults as target group. In study selection, all types of exercise and physical activity and any measure of weight change in aged adults (≥65 years) or postmenopausal women were considered. N=9 primary studies were identified. All were conducted in the US, with one study additionally including samples from Canada and the UK. Three studies focused on aged adults, while six concentrated specifically on postmenopausal women. Forms of exercise or physical activity comprised self-reported exercise history in four studies and low, moderate or high intensity exercise interventions in five studies. Four studies combined exercise with a hypocaloric diet and included comparison groups receiving either diet only, health education, stretching or a delayed intervention (one study each). Exercise was associated with weight loss (1.1-6 kg) in all intervention studies, all of which studied an overweight sample, and with weight maintenance in most observational studies, all of which studied a general population or otherwise overweight-unspecific sample. In sum, exercise and physical activity can effectively prevent weight gain in older adults and postmenopausal women either in terms of weight loss or maintenance. They can preserve lean body mass and thus are important for the balance between potentially positive and negative effects of weight reduction in later life. In addition, since all intervention studies were conducted with an overweight sample, it seems that primordial prevention (in terms of preventing the development of risk factors such as excess weight in the first place) might be a neglected issue in geriatric and postmenopausal prevention.

Sedentary behaviors and subsequent health outcomes in adults a systematic review of longitudinal studies, 1996-2011

CONTEXT

To systematically review and provide an informative synthesis of findings from longitudinal studies published since 1996 reporting on relationships between self-reported sedentary behavior and device-based measures of sedentary time with health-related outcomes in adults.

EVIDENCE ACQUISITION

Studies published between 1996 and January 2011 were identified by examining existing literature reviews and by systematic searches in Web of Science, MEDLINE, PubMed, and PsycINFO. English-written articles were selected according to study design, targeted behavior, and health outcome.

EVIDENCE SYNTHESIS

Forty-eight articles met the inclusion criteria; of these, 46 incorporated self-reported measures including total sitting time; TV viewing time only; TV viewing time and other screen-time behaviors; and TV viewing time plus other sedentary behaviors. Findings indicate a consistent relationship of self-reported sedentary behavior with mortality and with weight gain from childhood to the adult years. However, findings were mixed for associations with disease incidence, weight gain during adulthood, and cardiometabolic risk. Of the three studies that used device-based measures of sedentary time, one showed that markers of obesity predicted sedentary time, whereas inconclusive findings have been observed for markers of insulin resistance.

CONCLUSIONS

There is a growing body of evidence that sedentary behavior may be a distinct risk factor, independent of physical activity, for multiple adverse health outcomes in adults. Prospective studies using device-based measures are required to provide a clearer understanding of the impact of sedentary time on health outcomes.

Sedentary behavior and dietary intake in children, adolescents, and adults. A systematic review

CONTEXT

Sedentary behavior is implicated in youth and adult overweight and obesity. However, the relationship between sedentary behavior and weight status is often small or inconsistent, with few studies controlling for confounding factors such as diet and physical activity. Diet has been hypothesized to covary with some sedentary behaviors. It is opportune, therefore, to review whether dietary intake is associated with sedentary behavior in young people and adults. This may allow for better interpretation of the diversity of findings concerning sedentary behavior and weight status.

EVIDENCE ACQUISITION

Published English-language studies were located from computerized and manual searches in early 2010. Included studies were observational studies assessing an association between at least one sedentary behavior and at least one aspect of dietary intake in children (aged <11 years), adolescents (aged 12-18 years), or adults (aged >18 years).

EVIDENCE SYNTHESIS

Fifty-three studies, totaling 111 independent samples, were eligible for this review. Sedentary behavior in children (n=19, independent samples=24), adolescents (n=26, independent samples=72), and adults (n=11, independent samples=14) appears to be clearly associated with elements of a less healthy diet including lower fruit and vegetable consumption; higher consumption of energy-dense snacks, drinks, and fast foods; and higher total energy intake. Strengths of association were mainly in the small-to-moderate range.

CONCLUSIONS

The association drawn mainly from cross-sectional studies is that sedentary behavior, usually assessed as screen time and predominantly TV viewing, is associated with unhealthy dietary behaviors in children, adolescents, and adults. Interventions need to be developed that target reductions in sedentary time to test whether diet also changes.

Television viewing and incident cardiovascular disease: prospective associations and mediation analysis in the EPIC Norfolk Study

BACKGROUND

Although television viewing time is detrimentally associated with intermediate cardiovascular risk factors, the relationship with incident total (i.e. combined fatal and non-fatal) cardiovascular disease (CVD), non-fatal CVD and coronary heart disease is largely unknown. This study examined whether television viewing time is associated with these three outcomes, independently of physical activity energy expenditure and other confounding variables.

METHODOLOGY/PRINCIPAL FINDINGS

A population-based cohort of 12,608 men and women (aged 61.4±9.0), free from stroke, myocardial infarction and cancer at baseline in 1998-2000 were followed up until 2007 (6.9±1.9 years). Participants self-reported education, smoking, alcohol use, antihypertensive, lipid lowering and antidepressant medication, disease history, total energy intake, sleep duration, physical activity and television viewing. BMI, waist circumference, blood pressure, triglycerides, HDL cholesterol and glycated haemoglobin (HbA(1c)) were measured by standardized procedures; a clustered metabolic risk score was constructed. Every one hour/day increase in television viewing was associated with an increased hazard for total (HR = 1.06, 95%CI = 1.03-1.08; 2,620 cases), non-fatal CVD (HR = 1.06, 95%CI = 1.03-1.09; 2,134 cases), and coronary heart disease (HR = 1.08, 95%CI = 1.03-1.13; 940 cases), independent of gender, age, education, smoking, alcohol, medication, diabetes status, CVD family history, sleep duration and physical activity energy expenditure. Energy intake, BMI, waist circumference, blood pressure, triglycerides, HDL cholesterol, HbA(1c) and the clustered metabolic risk score only partially mediated these associations.

CONCLUSIONS

These results indicate that the most prevalent leisure time (sedentary) behaviour, television viewing, independently contributes to increased CVD risk. Recommendations on reducing television viewing time should be considered.

Sedentary behaviors and health outcomes among adults: a systematic review of prospective studies

CONTEXT

Nowadays, people spend a substantial amount of time per day on sedentary behaviors and it is likely that the time spent sedentary will continue to rise. To date, there is no review of prospective studies that systematically examined the relationship between diverse sedentary behaviors and various health outcomes among adults.

PURPOSE

This review aimed to systematically review the literature as to the relationship between sedentary behaviors and health outcomes considering the methodologic quality of the studies.

EVIDENCE ACQUISITION

In February 2010, a search for prospective studies was performed in diverse electronic databases. After inclusion, in 2010, the methodologic quality of each study was assessed. A best-evidence synthesis was applied to draw conclusions.

EVIDENCE SYNTHESIS

19 studies were included, of which 14 were of high methodologic quality. Based on inconsistency in findings among the studies and lack of high-quality prospective studies, insufficient evidence was concluded for body weight-related measures, CVD risk, and endometrial cancer. Further, moderate evidence for a positive relationship between the time spent sitting and the risk for type 2 diabetes was concluded. Based on three high-quality studies, there was no evidence for a relationship between sedentary behavior and mortality from cancer, but strong evidence for all-cause and CVD mortality.

CONCLUSIONS

Given the trend toward increased time in sedentary behaviors, additional prospective studies of high methodologic quality are recommended to clarify the causal relationships between sedentary behavior and health outcomes. Meanwhile, evidence to date suggests that interventions aimed at reducing sedentary behavior are needed.

State of the epidemiological evidence on physical activity and cancer prevention

BACKGROUND

Physical activity is a modifiable lifestyle risk factor that has the potential to reduce the risk of most major cancer sites.

METHODS

We examined the strength, consistency, dose-response and biological plausibility of an association between physical activity and risk of colon, breast, endometrium, lung, prostate, ovarian, gastric, rectal, pancreatic, bladder, testicular, kidney and haematological cancers. We also estimated the population-attributable risk (PAR) for physical inactivity and cancer in 15 European countries.

RESULTS

There is convincing or probable evidence for a beneficial effect of physical activity on the risk of colon, breast and endometrial cancers. The evidence is weaker for ovarian, lung and prostate cancers and generally either null or insufficient for all remaining cancers. Several hypothesised biological mechanisms include a likely effect of physical activity on insulin resistance, body composition, sex steroid hormones and a possible effect on vitamin D, adipokines, inflammation and immune function. Somewhere between 165,000 and 330,000 cases of the six major cancers (breast, colon, lung, prostate, endometrium and ovarian) could have been prevented in 2008 in Europe alone if the population had maintained sufficient levels of physical activity.

CONCLUSION

There is strong and consistent evidence that physical activity reduces the risk of several of the major cancer sites, and that between 9% and 19% of cancer cases could be attributed to lack of sufficient physical activity in Europe. Public health recommendations for physical activity and cancer prevention generally suggest 30-60 min of moderate or vigorous-intensity activity done at least 5d per week.

Associations between sitting time and weight in young adult Australian women

OBJECTIVE

Sedentary behaviour may be a contributor to weight gain in today's young adult women, who are gaining weight faster than women in their mothers' generation. The aim was to examine the relationships between sitting time and weight in young women.

METHOD

Data were from women born in 1973-1978 who completed surveys in 2000, 2003 and 2006 for the Australian Longitudinal Study on Women's Health. Associations between concurrent changes in sitting-time and weight, and prospective associations between these variables, were examined using ANOVA and linear regressions, stratified by BMI-category in 2000 (n=5562).

RESULTS

Among overweight and obese women, percentage weight change from 2000 to 2006 was higher in those whose sitting time increased (>20%) than in those whose sitting time decreased (>20%) over the same period (p<0.05). Conversely, percentage change in sitting time was significantly higher in those who gained weight (>5%) than in those who lost weight (>5%) (p<0.05). There were no prospective associations between (change in) sitting time and weight change, or between (change in) weight and change in sitting time.

CONCLUSION

The results confirm associations between concurrent changes in weight and changes in sitting time in overweight and obese women, but no prospective relationships were found.

Physical activity, sedentary behaviours, and the prevention of endometrial cancer

Physical activity has been hypothesised to reduce endometrial cancer risk, but this relationship has been difficult to confirm because of a limited number of prospective studies. However, recent publications from five cohort studies, which together comprise 2663 out of 3463 cases in the published literature for analyses of recreational physical activity, may help resolve this question. To synthesise these new data, we conducted a meta-analysis of prospective studies published through to December 2009. We found that physical activity was clearly associated with reduced risk of endometrial cancer, with active women having an approximately 30% lower risk than inactive women. Owing to recent interest in sedentary behaviour, we further investigated sitting time in relation to endometrial cancer risk using data from the NIH-AARP Diet and Health Study. We found that, independent of the level of moderate–vigorous physical activity, greater sitting time was associated with increased endometrial cancer risk. Thus, limiting time in sedentary behaviours may complement increasing level of moderate–vigorous physical activity as a means of reducing endometrial cancer risk. Taken together with the established biological plausibility of this relation, the totality of evidence now convincingly indicates that physical activity prevents or reduces risk of endometrial cancer.

Occupational sitting and health risks: a systematic review

CONTEXT

Emerging evidence suggests that sedentary behavior (i.e., time spent sitting) may be negatively associated with health. The aim of this study was to systematically review the evidence on associations between occupational sitting and health risks.

EVIDENCE ACQUISITION

Studies were identified in March-April 2009 by literature searches in PubMed, PsycINFO, CENTRAL, CINAHL, EMBASE, and PEDro, with subsequent related-article searches in PubMed and citation searches in Web of Science. Identified studies were categorized by health outcome. Two independent reviewers assessed methodologic quality using a 15-item quality rating list (score range 0-15 points, higher score indicating better quality). Data on study design, study population, measures of occupational sitting, health risks, analyses, and results were extracted.

EVIDENCE SYNTHESIS

43 papers met the inclusion criteria (21% cross-sectional, 14% case-control, 65% prospective); they examined the associations between occupational sitting and BMI (n=12); cancer (n=17); cardiovascular disease (CVD, n=8); diabetes mellitus (DM, n=4); and mortality (n=6). The median study-quality score was 12 points. Half the cross-sectional studies showed a positive association between occupational sitting and BMI, but prospective studies failed to confirm a causal relationship. There was some case-control evidence for a positive association between occupational sitting and cancer; however, this was generally not supported by prospective studies. The majority of prospective studies found that occupational sitting was associated with a higher risk of DM and mortality.

CONCLUSIONS

Limited evidence was found to support a positive relationship between occupational sitting and health risks. The heterogeneity of study designs, measures, and findings makes it difficult to draw definitive conclusions at this time.