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Journal ArticleDOI

Associations of objectively measured sedentary behaviour and physical activity with markers of cardiometabolic health.

TL;DR: In adults at high risk of type 2 diabetes mellitus, time spent sedentary is strongly and adversely associated with cardiometabolic health and may be a more important indicator of poor health than MVPA.
Abstract: Aims/hypothesis The study aimed to examine the associations between objectively measured sedentary time, breaks in sedentary time, moderate-to-vigorous physical activity (MVPA) and total physical activity with markers of cardiometabolic health in a population with known risk factors for type 2 diabetes mellitus.

Summary (1 min read)

Jump to: [Introduction][Methods][Results][Discussion] and [Duality of interest]

Introduction

  • Sedentary behaviour has previously been characterised as ≤1.5 metabolic equivalents (METs) [1, 2].
  • METs are the energy cost of physical activity and are expressed as multiples of resting metabolic rate- where one MET (or 3.5 ml min-1 kg-1) is equivalent to a typical metabolism at rest for an average person.
  • Many studies involving children and adolescents have reported minimal or no associations between sedentary time and markers of cardio-metabolic health and evidence in young adults remains limited, particularly in high risk populations [19, 20].
  • The authors hypothesised that all three constructs would be independently associated with health.

Methods

  • Cardiovascular, metabolic and anthropometric outcomes Markers of metabolic and cardiovascular health were measured, including fasting plasma glucose (FPG) and 2-hour plasma glucose (via an OGTT), HbA1c, total cholesterol, HDL cholesterol and triglycerides.
  • To further represent the strength of sedentary time and breaks in sedentary time with cardio-metabolic markers, variables were also examined as tertiles using analysis of covariance procedures.
  • Two-tailed p values of 0.05 or less were considered statistically significant for main effects.

Results

  • The majority of excluded participants failed to meet the minimum accelerometer wear time requirement.
  • In addition, there were no significant interactions for sex in the results for sedentary time, MVPA or breaks.

Discussion

  • This study of those at a high risk of type 2 diabetes mellitus recruited from primary care found that sedentary time was detrimentally associated with 2-hour glucose, triglycerides and HDL-cholesterol, independent of measured confounders.
  • In addition, participants were rigorously phenotyped with traditional markers of cardio-metabolic health using standardised biochemical procedures.
  • They rely on categorising movement strength, rather than directly distinguishing between sitting, lying and standing behaviours.
  • Surprisingly, there was no difference between the effect sizes found in the light or moderate intensity profiles.
  • The findings from this study need to be confirmed in different populations in order to establish a causal link between sedentary behaviour and cardio-metabolic dysfunction.

Duality of interest

  • The authors declare that there is no duality of interest associated with this manuscript.
  • JH and TY had original idea for the analysis, also known as Author Contributions.
  • JH, TY, SB, KK, EW, MN and MJD made substantial contributions to conception and design.
  • JH, CE and TG processed raw accelerometer files.
  • All authors reviewed/edited the manuscript and gave final approval of the version to be published.

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1
Title: Associations of objectively measured sedentary behaviour and physical activity
with markers of cardio-metabolic health
J. Henson, Leicester Diabetes Centre, Leicester General Hospital, UK
T. Yates, Department of Cardiovascular Sciences, University of Leicester, UK
S. J. H. Biddle, School of Sport, Exercise and Health Sciences, Loughborough University, UK
C. L. Edwardson, Leicester Diabetes Centre, Leicester General Hospital, UK
K. Khunti, Department of Health Sciences, University of Leicester, UK
E. G. Wilmot, Department of Cardiovascular Sciences, University of Leicester, UK
L. J. Gray, Department of Health Sciences, University of Leicester, UK
T. Gorely, School of Sport, Exercise and Health Sciences, Loughborough University, UK
M. A. Nimmo, School of Sport, Exercise and Health Sciences, Loughborough University, UK
M. J. Davies, Department of Cardiovascular Sciences, University of Leicester, UK
* All authors are affiliated with The NIHR Leicester-Loughborough Diet, Lifestyle and
Physical Activity Biomedical Research Unit which is a partnership between University
Hospitals of Leicester NHS Trust, Loughborough University and the University of Leicester.
Corresponding Author:
Mr Joseph Henson
Leicester Diabetes Centre
Leicester General Hospital
Leicester
LE5 4PW
UK
Email address: jjh18@le.ac.uk
Tel: +44 116 258 4436
Fax: +44116 258 4053.
Abstract word count= 240
Main text word count = 3,101
Number of Tables = 2
Number of Figures = 2

2
Abstract
Aims/hypothesis To examine the associations between objectively measured sedentary time,
breaks in sedentary time, moderate-to-vigorous physical activity (MVPA) and total physical
activity with markers of cardio-metabolic health in a population at a high risk of type 2
diabetes mellitus.
Methods This study reports data from two ongoing diabetes prevention programmes.
Participants at a high risk of type 2 diabetes were recruited from primary care practices
located within the East Midlands, United Kingdom, 2010-2011, using either a validated risk
score or medical records. Sedentary time (<100counts/min), MVPA (1952counts/min) and
total physical activity (counts) were measured using Actigraph GT3X accelerometers (15s
epochs). A break was considered as any interruption in sedentary time (100counts/min).
Linear regression analysis examined the associations with markers of cardio-metabolic health.
Results 878 participants comprising 153 from ‘Project STAND’ (age=32.9±5.6years;
female=71.2%) and 725 from ‘Walking Away from Diabetes’ (age=63.7±7.8years;
female=35.2%). Following adjustment for various covariates, including MVPA, there were
detrimental linear associations of sedentary time with 2-hour plasma glucose (standardised
beta co-efficient (β)) (β=0.220, p=<0.001), triglycerides (β=0.206, p=0.001) and HDL
cholesterol (β=-0.123, p=0.029). In contrast, after adjustment for sedentary time, MVPA was
significantly inversely associated with BMI (β=-0.215, p=<0.001) and waist circumference
(β=-0.228, p=<0.001), but not with measured biochemical variables. Breaks in sedentary time
were inversely associated with waist circumference (β=-0.215, p=<0.001) and BMI (β=-
0.151, p=0.001). Total physical activity was
Conclusions/Interpretation In adults at high risk of type 2 diabetes mellitus, time spent
sedentary is strongly and adversely associated with cardio-metabolic health. Furthermore,
sedentary time may be a more important indicator of poor health than MVPA.
Walking Away from Type 2 Diabetes Study - ISRCTN31392913.
Project STAND (Sedentary Time And Diabetes) -
ISRCTN08434554.
Keywords: Breaks in sedentary time, High-risk, Physical activity, Primary care, Sedentary
behaviour, Type 2 diabetes mellitus.
Abbreviations:
β- Beta-coefficient
cpm- Counts per minute
CVD- Cardiovascular disease
FPG- Fasting plasma glucose
IFG- Impaired fasting glycaemia
IGR- Impaired glucose regulation
IGT- Impaired glucose tolerance
IMD- Index of multiple deprivation
MVPA- Moderate-to-vigorous physical activity
METs- Metabolic equivalents
STAND- Sedentary Time And Diabetes
UK- United Kingdom

3
WA- Walking Away from type 2 diabetes
Introduction
Sedentary behaviour has previously been characterised as 1.5 metabolic equivalents (METs)
[1, 2]. METs are the energy cost of physical activity and are expressed as multiples of resting
metabolic rate- where one MET (or 3.5 ml min
-1
kg
-1
) is equivalent to a typical metabolism at
rest for an average person. Given the fact it is impractical to measure energy expenditure in
most studies and there are limited behaviours that involve both sitting and energy expenditure
(>1.5 METs), a more operational behavioural interpretation has been recommended, where
sedentary behaviour is defined as any non-exercise sitting time [3]. Over the last decade,
sedentary behaviour has emerged as a distinctive behavioural paradigm with detrimental
effects on chronic disease risk, independent of moderate- to vigorous-intensity physical
activity (MVPA) [4-8]. This new paradigm is conceptualised around two constructs: total
time spent sedentary and the number of breaks in sedentary behaviour (e.g. rising from a
sitting/lying position to standing). Both expressions show strong associations with markers of
cardio-metabolic health independent of each other and other lifestyle behaviours [4-6, 8, 9].
Epidemiological evidence examining the effect of time spent sedentary has tended to focus on
self-report measures [6, 10-12], which are prone to bias and have poor levels of validity [13].
Although several studies employing objective measures of sedentary behaviour have been
reported, most have been conducted in the general population [4, 5, 8, 14, 15]. It is therefore
unclear to what extent the reported associations are generalisable to those at high risk of
chronic disease. This is an important limitation as international recommendations and policies
specify that chronic disease prevention strategies should include targeted interventions aimed
at the identification and management of high risk individuals [16-18]. Therefore the
importance of sedentary behaviour in this group needs to be better understood in order to
inform the content and structure of prevention programmes.
The effect of age on the association between sedentary time and cardio-metabolic risk also
remains unclear. Many studies involving children and adolescents have reported minimal or
no associations between sedentary time and markers of cardio-metabolic health and evidence
in young adults remains limited, particularly in high risk populations [19, 20].
In this study, we examined the extent to which sedentary time, breaks in sedentary time, and
MVPA are independently associated with cardio-metabolic risk factors in a population
identified with a high risk of developing type 2 diabetes mellitus. We hypothesised that all
three constructs would be independently associated with health.
Methods
Participants This study used combined baseline data two prevention studies, Walking Away
from Type 2 Diabetes Study (WA) (ISRCTN31392913) and Project STAND (Sedentary Time
And Diabetes) (ISRCTN08434554), 2010-2011. Both trial protocols have been published
elsewhere [21, 22]. Briefly, WA is a randomised controlled trial investigating whether a
lifestyle intervention programme can promote behaviour change in those identified at high
risk of type 2 diabetes mellitus. Similarly, Project STAND is a randomised controlled trial
investigating the effect of structured education and self monitoring on reducing sedentary
time in young adults identified at high risk of developing type 2 diabetes mellitus.

4
Individuals were unaware of their diabetes risk status before entering both studies and all
participants were excluded if they had known type 2 diabetes mellitus or were taking steroids.
Baseline measurements across both studies were performed before treatment allocation by the
same team of trained staff who followed identical standard operating procedures. Informed
consent obtained from all eligible participants and both studies gained full ethical and
governance approvals from the Nottingham Research Ethics Committee and Leicestershire,
Northamptonshire and Rutland Comprehensive Local Research Network.
Walking Away Middle age and older adults (aged up to 74) were recruited from 10 primary
care practices within Leicestershire, United Kingdom (UK). Individuals at high risk of
impaired glucose regulation (IGR) (composite of impaired glucose tolerance (IGT) and/or
impaired fasting glycaemia (IFG)) or type 2 diabetes mellitus were identified using a
modified version of the automated Leicester Risk Score, specifically designed to be
administered in primary care [23]. An automated platform using medical records was used to
rank individuals for diabetes risk using predefined weighted variables (age, gender, BMI,
family history of type 2 diabetes mellitus and use of antihypertensive medication). Those
scoring within the 90
th
percentile in each practice were invited to take part in the study. This
approach has been shown to have reasonable sensitivity and specificity for identifying
participants at a high risk of IGR [23].
Project STAND Young adults who were at risk of developing type 2 diabetes mellitus from
across Leicestershire and the South East Midlands region were recruited from primary care
practices. Practices databases were searched for participants meeting the following inclusion
criteria: a) aged 18-40 years with a BMI in the obese range (30kg/m
2
; 27.5kg/m
2
for south
Asians) or b) aged 18-40 years with a BMI in the overweight range 25kg/m
2
(23kg/m
2
for
south Asians) plus one additional risk factor of a family history of type 2 diabetes mellitus or
cardiovascular disease (CVD), previous gestational diabetes, polycystic ovarian syndrome,
HbA1c 5.8% or IGR [24].
Cardiovascular, metabolic and anthropometric outcomes Markers of metabolic and
cardiovascular health were measured, including fasting plasma glucose (FPG) and 2-hour
plasma glucose (via an OGTT), HbA1c, total cholesterol, HDL cholesterol and triglycerides.
Venous blood samples were obtained following an overnight fast and all assays were
measured in the same laboratory located within the Leicester Royal Infirmary, UK. Analysis
was conducted by individuals blinded to the patients' identity, using stable methodologies,
standardised to external quality assurance values. Plasma glucose was analysed in venous
samples via the hexokinase method. HbA1c was analysed using the Bio-Rad Variant II HPLC
system (Bio-Rad Clinical Diagnostics, Hemel Hempstead, UK). HDL-cholesterol and
triglycerides were measured using standard enzymatic techniques.
Body weight (Tanita TBE 611, Tanita, West Drayton, UK) and waist circumference
(midpoint between the lower costal margin and iliac crest) were measured to the nearest 0.1
kg and 0.5 cm respectively. Information on current smoking status, medication and ethnicity
was obtained following an interview administered protocol with a health care professional.
Social deprivation was determined by assigning an Index of Multiple Deprivation (IMD)
score to the participant’s resident area [25]. IMD scores
are publically available continuous
measures of compound social and material deprivation which are calculated using a variety of
data including current income, employment, education and housing.

Citations
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Journal ArticleDOI
13 Oct 2015-PLOS ONE
TL;DR: Time spent in MVPA is an important target for intervention and preventing transfer of time from LIPA to SB might lessen the negative effects of physical inactivity, so time spent in each of these behaviors are codependent.
Abstract: The associations between time spent in sleep, sedentary behaviors (SB) and physical activity with health are usually studied without taking into account that time is finite during the day, so time spent in each of these behaviors are codependent. Therefore, little is known about the combined effect of time spent in sleep, SB and physical activity, that together constitute a composite whole, on obesity and cardio-metabolic health markers. Cross-sectional analysis of NHANES 2005–6 cycle on N = 1937 adults, was undertaken using a compositional analysis paradigm, which accounts for this intrinsic codependence. Time spent in SB, light intensity (LIPA) and moderate to vigorous activity (MVPA) was determined from accelerometry and combined with self-reported sleep time to obtain the 24 hour time budget composition. The distribution of time spent in sleep, SB, LIPA and MVPA is significantly associated with BMI, waist circumference, triglycerides, plasma glucose, plasma insulin (all p<0.001), and systolic (p<0.001) and diastolic blood pressure (p<0.003), but not HDL or LDL. Within the composition, the strongest positive effect is found for the proportion of time spent in MVPA. Strikingly, the effects of MVPA replacing another behavior and of MVPA being displaced by another behavior are asymmetric. For example, re-allocating 10 minutes of SB to MVPA was associated with a lower waist circumference by 0.001% but if 10 minutes of MVPA is displaced by SB this was associated with a 0.84% higher waist circumference. The proportion of time spent in LIPA and SB were detrimentally associated with obesity and cardiovascular disease markers, but the association with SB was stronger. For diabetes risk markers, replacing SB with LIPA was associated with more favorable outcomes. Time spent in MVPA is an important target for intervention and preventing transfer of time from LIPA to SB might lessen the negative effects of physical inactivity.

627 citations

Journal ArticleDOI
TL;DR: Interventions based on environmental restructuring, persuasion, or education were most promising, and future sedentary reduction interventions might most fruitfully incorporate environmental modification and self-regulatory skills training.
Abstract: Sedentary behaviour – i.e., low energy-expending waking behaviour while seated or lying down – is a health risk factor, even when controlling for physical activity. This review sought to describe the behaviour change strategies used within interventions that have sought to reduce sedentary behaviour in adults. Studies were identified through existing literature reviews, a systematic database search, and hand-searches of eligible papers. Interventions were categorised as ‘very promising’, ‘quite promising’, or ‘non-promising’ according to observed behaviour changes. Intervention functions and behaviour change techniques were compared across promising and non-promising interventions. Twenty-six eligible studies reported thirty-eight interventions, of which twenty (53%) were worksite-based. Fifteen interventions (39%) were very promising, eight quite promising (21%), and fifteen non-promising (39%). Very or quite promising interventions tended to have targeted sedentary behaviour instead of physical activity. Interventions based on environmental restructuring, persuasion, or education were most promising. Self-monitoring, problem solving, and restructuring the social or physical environment were particularly promising behaviour change techniques. Future sedentary reduction interventions might most fruitfully incorporate environmental modification and self-regulatory skills training. The evidence base is, however, weakened by low-quality evaluation methods; more RCTs, employing no-treatment control groups, and collecting objective data are needed.

351 citations


Cites background from "Associations of objectively measure..."

  • ...While those who spend more time in sedentary behaviour tend to do less moderate-to-vigorous physical activity (Mansoubi, Pearson, Biddle, & Clemes, 2014), the potentially independent health impacts of sedentary behaviour and physical activity mean that activity-promotion may fail to offset the health impact of sedentary behaviour (Henson et al., 2013)....

    [...]

  • ...…tend to do less moderate-to-vigorous physical activity (Mansoubi, Pearson, Biddle, & Clemes, 2014), the potentially independent health impacts of sedentary behaviour and physical activity mean that activity-promotion may fail to offset the health impact of sedentary behaviour (Henson et al., 2013)....

    [...]

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TL;DR: Initial guidelines for employers to promote the avoidance of prolonged periods of sedentary work and promote among their staff that prolonged sitting may significantly and independently increase the risk of cardiometabolic diseases and premature mortality are suggested.
Abstract: An international group of experts convened to provide guidance for employers to promote the avoidance of prolonged periods of sedentary work. The set of recommendations was developed from the totality of the current evidence, including long-term epidemiological studies and interventional studies of getting workers to stand and/or move more frequently. The evidence was ranked in quality using the four levels of the American College of Sports Medicine. The derived guidance is as follows: for those occupations which are predominantly desk based, workers should aim to initially progress towards accumulating 2 h/day of standing and light activity (light walking) during working hours, eventually progressing to a total accumulation of 4 h/day (prorated to part-time hours). To achieve this, seated-based work should be regularly broken up with standing-based work, the use of sit–stand desks, or the taking of short active standing breaks. Along with other health promotion goals (improved nutrition, reducing alcohol, smoking and stress), companies should also promote among their staff that prolonged sitting, aggregated from work and in leisure time, may significantly and independently increase the risk of cardiometabolic diseases and premature mortality. It is appreciated that these recommendations should be interpreted in relation to the evidence from which they were derived, largely observational and retrospective studies, or short-term interventional studies showing acute cardiometabolic changes. While longer term intervention studies are required, the level of consistent evidence accumulated to date, and the public health context of rising chronic diseases, suggest initial guidelines are justified. We hope these guidelines stimulate future research, and that greater precision will be possible within future iterations.

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TL;DR: Key issues to consider when using the activPAL in physical activity and sedentary behavior field-based research with adult populations are summarised and examples from current literature and experiences are presented.

306 citations

References
More filters
Journal ArticleDOI
TL;DR: These data provide a template on which patterns of activity can be classified into intensity levels using the CSA accelerometer, and help to predict energy expenditure at any treadmill speed.
Abstract: Purpose:We established accelerometer count ranges for the Computer Science and Applications, Inc. (CSA) activity monitor corresponding to commonly employed MET categories.Methods:Data were obtained from 50 adults (25 males, 25 females) during treadmill exercise at three different speeds (4.8

3,267 citations


"Associations of objectively measure..." refers methods in this paper

  • ...Freedson cutpoints were used to categorise each epoch as sedentary (<25 counts per 15 s), light-intensity physical activity (≥25 to <488 counts per 15 s) or MVPA (≥488 counts per 15 s) [24]....

    [...]

Journal ArticleDOI
TL;DR: Accelerometer-based activity assessments requires careful planning and the use of appropriate strategies to increase compliance, and face-to-face distribution and collection of accelerometers is probably the best option in field-based research, but deliveries by express carrier or registered mail is a viable option.
Abstract: Purpose: The purpose of this review is to address important methodological issues related to conducting accelerometer-based assessments of physical activity in free-living individuals. Methods: We review the extant scientific literature for empirical information related to the following issues: product selection, number of accelerometers needed, placement of accelerometers, epoch length, and days of monitoring required to estimate habitual physical activity. We also discuss the various options related to distributing and collecting monitors and strategies to enhance compliance with the monitoring protocol. Results: No definitive evidence exists currently to indicate that one make and model of accelerometer is more valid and reliable than another. Selection of accelerometer therefore remains primarily an issue of practicality, technical support, and comparability with other studies. Studies employing multiple accelerometers to estimate energy expenditure report only marginal improvements in explanatory power. Accelerometers are best placed on hip or the lower back. Although the issue of epoch length has not been studied in adults, the use of count cut points based on 1-min time intervals maybe inappropriate in children and may result in underestimation of physical activity. Among adults, 3-5 d of monitoring is required to reliably estimate habitual physical activity. Among children and adolescents, the number of monitoring days required ranges from 4 to 9 d, making it difficult to draw a definitive conclusion for this population. Face-to-face distribution and collection of accelerometers is probably the best option in field-based research, but delivery and return by express carrier or registered mail is a viable option. Conclusion: Accelerometer-based activity assessments requires careful planning and the use of appropriate strategies to increase compliance.

1,824 citations


"Associations of objectively measure..." refers methods in this paper

  • ...In order for data to be included in the analysis, participants required at least four valid days of measurement [25]....

    [...]

Journal ArticleDOI
TL;DR: Evidence suggests that daily TV viewing in excess of 2 hours is associated with reduced physical and psychosocial health, and that lowering sedentary time leads to reductions in BMI.
Abstract: Accumulating evidence suggests that, independent of physical activity levels, sedentary behaviours are associated with increased risk of cardio-metabolic disease, all-cause mortality, and a variety of physiological and psychological problems. Therefore, the purpose of this systematic review is to determine the relationship between sedentary behaviour and health indicators in school-aged children and youth aged 5-17 years. Online databases (MEDLINE, EMBASE and PsycINFO), personal libraries and government documents were searched for relevant studies examining time spent engaging in sedentary behaviours and six specific health indicators (body composition, fitness, metabolic syndrome and cardiovascular disease, self-esteem, pro-social behaviour and academic achievement). 232 studies including 983,840 participants met inclusion criteria and were included in the review. Television (TV) watching was the most common measure of sedentary behaviour and body composition was the most common outcome measure. Qualitative analysis of all studies revealed a dose-response relation between increased sedentary behaviour and unfavourable health outcomes. Watching TV for more than 2 hours per day was associated with unfavourable body composition, decreased fitness, lowered scores for self-esteem and pro-social behaviour and decreased academic achievement. Meta-analysis was completed for randomized controlled studies that aimed to reduce sedentary time and reported change in body mass index (BMI) as their primary outcome. In this regard, a meta-analysis revealed an overall significant effect of -0.81 (95% CI of -1.44 to -0.17, p = 0.01) indicating an overall decrease in mean BMI associated with the interventions. There is a large body of evidence from all study designs which suggests that decreasing any type of sedentary time is associated with lower health risk in youth aged 5-17 years. In particular, the evidence suggests that daily TV viewing in excess of 2 hours is associated with reduced physical and psychosocial health, and that lowering sedentary time leads to reductions in BMI.

1,782 citations


"Associations of objectively measure..." refers background in this paper

  • ...Many studies involving children and adolescents have reported minimal or no associations between sedentary time and markers of cardio-metabolic health and evidence in young adults remains limited, particularly in high risk populations [19, 20]....

    [...]

Journal ArticleDOI
TL;DR: This work proposes that journal editors adopt a consistent definition of the term sedentary and require that all manuscripts published within their journal adhere to this common terminology, and suggests that authors use the term “inactive” to describe those who are performing insufficient amounts of MVPA.
Abstract: There has recently been an increase in research related to the health impact of sedentary behaviour (e.g., sitting) (Tremblay et al. 2010). Numerous studies suggest that those who engage in high amounts of sedentary behaviour can be at increased risk of morbidity and mortality regardless of their level of moderateto vigorous-intensity physical activity (MVPA) (Dunstan et al. 2010; Grøntved and Hu 2011; Katzmarzyk et al. 2009; Thorp et al. 2011; Wijndaele et al. 2011). Further, it has been noted that there is often little association between sedentary behaviour and MVPA (Biddle et al. 2004; Ekelund et al. 2006) and that it is possible for an individual to accumulate large amounts of both MVPA and sedentary behaviour in the course of a day (Healy et al. 2008; Katzmarzyk et al. 2009; Owen et al. 2010; Tremblay et al. 2010; Wong and Leatherdale 2008). Taken together, these findings suggest that too much sitting and too little MVPA represent separate and distinct risk factors for chronic, noncommunicable diseases (e.g., cardiovascular disease, diabetes, cancer). While research into the biology and health impact of sedentary behaviour represents an exciting new field of study, current inconsistencies in terminology are confusing for students, researchers, policymakers, and the general public. In short, the term “sedentary” currently has two separate and contradictory operational definitions. In this emerging field of research, sedentary behaviours are typically defined by both low energy expenditure (e.g., resting metabolic rate, typically ≤1.5 metabolic equivalents (METs)) and a sitting or reclining posture (Owen et al. 2010; Pate et al. 2008; Tremblay et al. 2010). In this context, a person may be described as sedentary if they engage in a large amount of sedentary behaviour. In contrast, in the sport and exercise literature the term sedentary is frequently used to describe the absence of some threshold of MVPA (Church et al. 2009; Melanson et al. 2009; Mullen et al. 2011; Sims et al. 2012; Smith et al. 2010). Thus, it is common for researchers in this field to describe a participant as sedentary because they are not meeting physical activity guidelines. Hence, many exercise studies include a “sedentary control group” or refer to their participants as coming from a “sedentary population” because of their lack of physical activity without actually measuring or assessing their level of sedentary behaviour. It is not difficult to see how these conflicting definitions of the term sedentary can easily lead to confusion. When reading the title or abstract of an article, it is often difficult to ascertain which definition of sedentary the authors have employed. If an article focuses on the health impact of a “sedentary lifestyle”, are they concerned with excessive sitting–lying down, the lack of physical activity, or both? Further, it is surprisingly common for articles within a given academic journal to oscillate between one definition and the other. To prevent further confusion, we propose that journal editors adopt a consistent definition of the term sedentary and require that all manuscripts published within their journal adhere to this common terminology. We suggest that journals formally define sedentary behaviour as any waking behaviour characterized by an energy expenditure ≤1.5 METs while in a sitting or reclining posture. In contrast, we suggest that authors use the term “inactive” to describe those who are performing insufficient amounts of MVPA (i.e., not meeting specified physical activity guidelines). The formal adoption of the above definitions by journal editors and reviewers would greatly improve the clarity of research and discussion related to these important health behaviours and help researchers searching for studies specific to sedentary behaviour or physical inactivity. We hope the research community will support these definitions and we look forward to further improvements in our understanding of the health impacts of sedentary behaviour and physical activity.

1,653 citations

Journal ArticleDOI
01 Nov 2007-Diabetes
TL;DR: There is an emergence of inactivity physiology studies beginning to raise a new concern with potentially major clinical and public health significance: the average nonexercising person may become even more metabolically unfit in the coming years if they sit too much, thereby limiting the normally high volume of intermittent nonexercise physical activity in everyday life.
Abstract: It is not uncommon for people to spend one-half of their waking day sitting, with relatively idle muscles. The other half of the day includes the often large volume of nonexercise physical activity. Given the increasing pace of technological change in domestic, community, and workplace environments, modern humans may still not have reached the historical pinnacle of physical inactivity, even in cohorts where people already do not perform exercise. Our purpose here is to examine the role of sedentary behaviors, especially sitting, on mortality, cardiovascular disease, type 2 diabetes, metabolic syndrome risk factors, and obesity. Recent observational epidemiological studies strongly suggest that daily sitting time or low nonexercise activity levels may have a significant direct relationship with each of these medical concerns. There is now a need for studies to differentiate between the potentially unique molecular, physiologic, and clinical effects of too much sitting (inactivity physiology) separate from the responses caused by structured exercise (exercise physiology). In theory, this may be in part because nonexercise activity thermogenesis is generally a much greater component of total energy expenditure than exercise or because any type of brief, yet frequent, muscular contraction throughout the day may be necessary to short-circuit unhealthy molecular signals causing metabolic diseases. One of the first series of controlled laboratory studies providing translational evidence for a molecular reason to maintain high levels of daily low-intensity and intermittent activity came from examinations of the cellular regulation of skeletal muscle lipoprotein lipase (LPL) (a protein important for controlling plasma triglyceride catabolism, HDL cholesterol, and other metabolic risk factors). Experimentally reducing normal spontaneous standing and ambulatory time had a much greater effect on LPL regulation than adding vigorous exercise training on top of the normal level of nonexercise activity. Those studies also found that inactivity initiated unique cellular processes that were qualitatively different from the exercise responses. In summary, there is an emergence of inactivity physiology studies. These are beginning to raise a new concern with potentially major clinical and public health significance: the average nonexercising person may become even more metabolically unfit in the coming years if they sit too much, thereby limiting the normally high volume of intermittent nonexercise physical activity in everyday life. Thus, if the inactivity physiology paradigm is proven to be true, the dire concern for the future may rest with growing numbers of people unaware of the potential insidious dangers of sitting too much and who are not taking advantage of the benefits of maintaining nonexercise activity throughout much of the day.

1,577 citations


"Associations of objectively measure..." refers background in this paper

  • ...Previous laboratory work has identified that distinctive physiological pathways are activated with increased sedentary behaviour, particularly around the metabolism of lipoprotein lipase, which remains largely unaffected by MVPA [36]....

    [...]

Related Papers (5)
Frequently Asked Questions (11)
Q1. What are the contributions in "Title: associations of objectively measured sedentary behaviour and physical activity with markers of cardio-metabolic health" ?

In this paper, the main text word count was 3,101 and the number of tables and figures was 2. 

Walking Away Middle age and older adults (aged up to 74) were recruited from 10 primary care practices within Leicestershire, United Kingdom (UK). 

Sedentary time (<100counts/min), MVPA (≥1952counts/min) and total physical activity (counts) were measured using Actigraph GT3X accelerometers (15s epochs). 

Associations of breaks in sedentary time with markers of health, independent of overall time spent sedentary and in MVPA, were less consistent, although beneficial associations were observed with measures of adiposity. 

The non-significant results observed for FPG and HbA1c are consistent with previous research on physical activity and sedentary behaviour [4, 14, 34] and reflect the different pathophysiological process underlying 2-hour and FPG regulation, with 2-hour glucose largely influenced by peripheral insulin resistance [34, 35]. 

Self-reported sedentary behaviour in the form of television viewing time has been positively associated with a multitude of cardio-metabolic risk factors [6, 28-30], including 2- hour glucose [28, 29]. 

This study of those at a high risk of type 2 diabetes mellitus recruited from primary care found that sedentary time was detrimentally associated with 2-hour glucose, triglycerides and HDL-cholesterol, independent of measured confounders. 

diabetes and cardiovascular prevention programmes concentrating solely on MVPA may overlook an area that is of fundamental importance to cardio-metabolic health. 

Their findings, therefore, highlight the importance of using 2-hour glucose as the primary outcome variable when assessing the impact of sedentary time on cardio-metabolic risk. 

recent reviews also report that self-reported sedentary time is consistently associated with an increased risk of diabetes [9] and the metabolic syndrome [31].8 

Their results extend those from other studies that have utilised both self-reported and objective measures of sedentary time and MVPA with cardio-metabolic variables in the general population.