Wishing you a healthy, active holiday season and New Year.
Best wishes from SBRN!
Recipe for a healthy day: how compositional data analysis can help us optimise our daily routine to be healthy.
Today’s post comes from Dr Sebastien Chastin at Glasgow Caledonian University.
What is the recipe for a healthy day?
This is the question we explore in our research article “Combined Effects of Time Spent in Physical Activity, Sedentary Behaviors and Sleep on Obesity and Cardio-Metabolic Health Markers: A Novel Compositional Data Analysis Approach” published by PLOS One. In this article, we argue that if we really want to know how much time we should spend; sleeping, sitting, standing, walking and exercising every day to be in good health, we have to adopt a compositional data paradigm. This is because, it is the only adequate mathematical representation of the pattern of time spent in different activities or behaviours throughout the day. In other words, one that takes into account the fact that time spent in one type of activity cannot be spent in another type of activity.
While developing this novel approach, initially just to overcome some technical issues with collinearity, we realised that it was more than just a new statistical technique. It actually provided an interesting unifying conceptual framework to study the impact and determinants of daily pattern of time use in an integrated and multidisciplinary way. In this blog piece, I would like to touch on some of these aspects.
It is helpful first to think about some analogous problems.
If I want to cook a tasty and healthy dish, nutritionists tell me that I have to combine in my recipe the right proportion of fat, carbohydrates, protein, vitamins, etc… and a good chef will tell me what ingredients to use and in what proportion. In the same way, to formulate an effective pill, pharmacologists combine active and inert compounds in the right proportions, ensuring that all ingredients are compatible and that their interactions do not alter or blunt the desired effect. Both my dish and the medical pills are fundamentally compositions. A composition is an entity of multiple non-overlapping parts which sum to a whole. Figure 1, shows different compositional representation of my dish and a medical pill, in graphical and mathematical terms. I apologise to nutritionists and pharmacologists if I did not get the number quite right to make these compositions actually healthy.
Similarly, our pattern of time use during the day is fundamentally a composition. For example we might describe the pattern of daily time use as
24 hour day = 8 hours (33.3%) sleep + 8 hours (33.3%) of work + 8 hours of leisure (33.3%)
Waking day = 2% Moderate to vigorous activity + 38% Light activity + 60% Sedentary behaviour
I am sure that you have, at least once, represented the pattern of daily time use with a pie chart as in figure 2. You might not have realised it but this is already compositional data analysis, but let’s see how we can take it further.
An interesting property of compositions is that their effect is determined by the proportion of the various basic ingredients that constitute them and not solely by the amount of one of these.
Surely, not! Let’s see how we can change the effect of my dish or pill. To make my drug more potent I need to absorb more of the active ingredient. To do this I can either take more pills of the same composition, or I can include more active ingredients in my pill, changing its composition. Similarly, I can eat less fat if I include less fat in my dish, but then its composition changed or I can eat less of the dish but I am still swallowing the same composition. In either case, the dose response depends on both the composition and the size.
This property becomes more important in the context of time use because to be healthy we can only change the composition of the day – we can’t make it any longer or shorter! In our paper we have actually shown that the composition of the day in terms of time spent in sleep, sedentary behaviour, light and moderate to vigorous activity is associated with adiposity and cardiometabolic markers. To be more active, I have to change the composition of my day. if I want to go to the gym and exercise I have to take time away from something else.
Conceptually, this is quite a departure from how we have usually considered time spent in physical activity, sleep or sedentary behaviour research. To date, we have conceptualised these as independent quantities of time and our reasoning and all the statistics we use to probe for evidence are based on this assumption. For example, we considered that health depends on the amount of time we spend exercising daily but did not address the fact that this time depends on the composition of the day. Our models and evidence rest on the underlying assumption that this time can be increased to infinity. Our current recipe for a healthy day is a minimum of daily 30 minutes of moderate to vigorous activity. This is roughly 2% of the time we have in a day. This recipe assumes that the remaining 98% of the day either has no impact on health or just the mirror opposite effect. This Manichaean concept would work if exercise was indeed the only ingredient of the day that impacts health.
However, we have more recently started to consider, that too much sitting might be bad for health, that sleep time is important for health, and that time spent in light activities might influence adiposity and glycaemic control. Since then, we have struggled to integrate and explain these within our current conceptual model of the day. This has led to some interesting controversies. A good example is contained in the article by Maher et al. 2014 published in PloS One and the comments it attracted . Some scientists claim that sitting has effects on health regardless of the amount of moderate to vigorous activity, while others respond that sitting time is just inactive time and that the associations reported are only due to sitting displacing physical activity. This will be familiar to you, and I have certainly heard the same arguments in numerous conferences. I found neither of these hypothesis satisfying. On one hand is it really reasonable to consider that the effect of sitting is independent when we know that time spent sitting and active are necessarily co-dependent and sitting necessarily displaces some active time? On the other, the dualist view activity/inactivity does not explain some of the lab results we have on sitting [2,3] and can’t account for the differences in effect we observed between sitting and light activity. Our field of research seems to be polarised in a dead lock as evidence seems to remain equivocal and flaunt by statistical difficulties such as collinearity.
This is why compositional data analysis is so attractive, it certainly enables us to overcome collinearity issues and to account in statistical models for time spent in all behaviours or categories of activity. But more importantly it offers a unifying way forward.
From a compositional stand point, the hypotheses above are not antithetic but complementary. Spending time sitting can have both specific health effects and displace active time thus contributing to the effects of inactivity. Our results clearly show this. The compositional approach does not invalidate or contradict any of our evidence to date; actually our results are consistent with it all. Instead it provides a sound theoretical framework and the practical statistical tools to integrate them so that we can move forward.
Let’s face it most of us struggle to fit in 2% of our time in exercise, so finding out how to optimise the rest of the day is of interest to a lot of people. Besides that, we cannot exercise all day, so why not act on the whole distribution of time to improve health. Compositional analysis can help us get to the recipe for healthy day.
We are currently developing resources, training material and workshops about compositional data analysis and we would like to hear from people who might be interested in these or better in helping and collaborating toward developing a larger open science project using compositional data analysis to formulate the recipe for a healthy day.
- Maher C, Olds T, Mire E, Katzmarzyk PT. Reconsidering the Sedentary Behaviour Paradigm. Johannsen D, editor. PLoS One. Public Library of Science; 2014;9: e86403. doi:10.1371/journal.pone.0086403
- Dunstan DW, Kingwell BA, Larsen R, Healy GN, Cerin E, Hamilton MT, et al. Breaking Up Prolonged Sitting Reduces Postprandial Glucose and Insulin Responses. Diabetes Care. 2012; doi: 10.2337/dc11–1931.
- Chastin SFM, Egerton T, Leask C, Stamatakis E. Meta-analysis of the relationship between breaks in sedentary behavior and cardiometabolic health. Obesity (Silver Spring). 2015;23: 1800–10. doi:10.1002/oby.21180
- Zeljko Pedisic. Measurement issues and poor adjustments for physical activity and sleep undermine sedentary behaviour research. Kinesiology. 2014;46: 135–146.
This post was originally published on Obesity Panacea.
Dr Ragnar Viir is looking for participants to complete an online survey looking at the way that sitting impacts muscle function.
From the survey:
Muscular activity, movement, keep us healthy. Excessive sitting is a risk factor for poor health and shorter life expectancy. The process starts from sitting per se – but what happen to muscles when we are sitting?
Here we explore whether the digital 3PPIUTT test (Three Position Personally Informative Upper Trapezius muscle Test) can be used to distinguish qualitative differences between standing, sitting and lying positions. Test results can enhance our understanding of how to recover from upright positions´ related muscular stress.
Method: Respondents are asked to investigate their own Upper Trapezius (UT) muscles in two ways.
1) Gently squeezing the muscle to form an opinion of muscle stiffness in sitting, standing and supine,
2) Pulling muscle, fixed by thumb and fingers´ pincer-like grip in frontal (to nose) direction alternately with pulling muscle in dorsal direction, forms opinion of muscle tension; again in three sitting, standing and supine positions.
Respondents should use thumb and fingers in a pincer-like grip and test left side muscle with right hand and right side muscle with left hand. Next page videos show location of Upper Trapezius (UT) muscle and using the thumb and fingers´ pincer-like grip to test UT muscle.
Subjective assessments of muscle stiffness and tension please mark on a scale of 1-5 where: 1 = Most relaxed and 5 = Most stiff / Most tensed.
By completing and submitting this survey you are providing consent for your results to be used for research purposes.
Tallinn Medical Research Ethics Committee (TMREC) has given acceptance nr 307 (application nr 1054, TMREC protocol nr 174) to Ragnar Viir Limited Partnership, principal investigator Dr. Ragnar Viir PhD
The survey can be found here.
Today’s post comes from Dr. Tarun Katapally. You can find more on Dr. Katapally at the bottom of this post.
We all seem to understand and experience the impact of weather on our movement patterns, yet most active living research is conducted without taking weather variation into account. In temperate climatic zones, and especially in Canada, we experience a wide variation in seasonal weather – not to mention adverse weather within seasons. Yet, in understanding the role of different contexts (i.e., urban design and neighbourhood built environment, school, home and recreational environment) in facilitating active living, weather seems to be ignored consistently.
It is true that we have no control over weather patterns. However, we do have the capacity to inform and influence policies that drive the environmental factors in our neighbourhoods, work places and schools. Individuals living in some neighbourhoods might have more access and amenities that may enable them to counter adverse weather and be active in all weather conditions. The same rationale applies to work places, schools or any other environmental context we are exposed to everyday. In informing policymakers, why aren’t we including weather variation in our analyses so that we can understand what physical and social environmental factors moderate the impact of adverse weather?
In Canada, time-stamped weather data are readily available through Environment Canada and this data could be easily linked with either accelerometry or self-report data. We appreciate that most accelerometry data are cross-sectional and hence, we have developed a methodology to link this cross-sectional data with weather data to study the influence urban design and built environment on children’s moderate to vigorous physical activity. This study has now been published in BMJ Open: bmjopen.bmj.com/content/5/11/e009045.full?keytype=ref&ijkey=3i5wwwyzlgy2cS2
Moreover, the article describing the methodology of the data linkage has itself been accepted for publication in the Canadian Journal of Public Health and will be available in early 2016. The methods used to capture weather variation and link weather data with accelerometry data could not only be replicated, but also modified or adapted. More importantly, researchers could easily adopt the overall approach of taking weather into account in active living research. We hope that weather variation, a perennial factor that interacts with all other environmental variables to influence active living, is not ignored in generating and translating knowledge to policymakers.
Dr. Katapally is a medical doctor trained in India and a population health policy researcher. He is currently a faculty member at the Johnson-Shoyama Graduate School of Public Policy that is based at the Universities of Regina and Saskatchewan. He is also an adjunct faculty member in the Department of Community Health and Epidemiology at the University of Saskatchewan. Dr. Katapally’s expertise is in the employment of advanced mixed-methods and complex analytical techniques to understand the influence of policy and policy-driven social and physical contexts on the influence of children’s physical activity and sedentary behaviour.
The Sedentary Behaviour Research Network (SBRN) is celebrating signing up its 1,000th member.
Launched in 2011, SBRN is the only organization for researchers and health professionals which focuses specifically on the health impact of sedentary behaviour. The Network has grown steadily since 2011 and includes prominent researchers in the areas of physiology, epidemiology, psychology, and ergonomics. Further, the Network’s membership has also published a letter promoting a standardized and more robust definition of sedentary behaviour that can be applied consistently across research domains, which has been co-published in both French and English in 3 separate journals and translated into several other languages. The Network’s members have also organized in-person meetings at conferences in Europe, North America, and Australia.
SBRN Membership reached the landmark figure when Dr. Freda Patterson, Assistant Professor of Health Promotion in the Department of Behavioral Health and Nutrition at the University of Delaware, joined several weeks ago.
Dr. Patterson’s work focuses on cardiovascular health and in particular, the promotion of heart health behaviors such as increased physical activity, decreased sedentary behavior and smoking cessation in at-risk populations. To this end, she has worked across the health promotion spectrum with both clinical and community based organizations to conceptualize, implement and evaluate novel programming around these behavioral targets. She has over 60 peer-reviewed publications and has received funding from agencies including the American Heart Foundation, the Barra foundation and Robert Wood Johnson to continue her work.
Congratulations to Dr. Patterson – and to all SBRN members – for contributing to the Network’s past and ongoing success!
The below study may be of interest to SBRN members. Please see details below.
As a practitioner or researcher whose work is in some way connected with physical activity, sedentary time and/or sleep, you are being invited to participate in a survey soliciting your opinion on a draft of Canada’s Integrated 24-Hour Movement Behaviour Guidelines for Children and Youth: an integration of physical activity, sedentary behavior and sleep (herein referred to as the Integrated Guidelines).
Traditionally, research examining the health implications of physical activity, sedentary behaviour, and sleep among children and youth has been conducted in movement behaviour silos, even though these behaviours do not occur in isolation of each other and have intuitive and empirical interactions. A body of research indicates that an integrated or holistic approach is more effective in changing behaviour resulting in a larger impact on health indicators, compared to an approach that only focuses on individual risk factors. Feedback from Canadian pediatricians, our knowledge user colleagues, and our expert international collaborators indicates that evidence-informed 24-hour guidelines that integrate physical activity, sedentary behaviour and sleep are needed and preferred over separate guides in order to enhance the promotion of healthy active lifestyles among children and youth across Canada.
With leadership from the Canadian Society for Exercise Physiology, a group of Canadian and International research and practice experts in physical activity, sedentary behaviour, sleep, and health promotion were convened to participate in the development of the Integrated Guidelines. After reviewing and consolidating the existing bodies of evidence in physical activity, sedentary behaviour and sleep, the experts have produced an initial version of the Integrated Guidelines.
One of the final stages in the development of the Integrated Guidelines is to gain feedback about the clarity of the guidelines, as well as level of agreement, perceived importance, and support for the guidelines from a large number of practitioners (e.g., pediatrics, education, public health, health promotion, physical activity, etc.). Acceptance and dissemination of the Integrated Guidelines is important for the alignment of strategic efforts in policy, practice, and research aimed at promoting health for Canadian children.
Participation in this survey is voluntary. By accessing and completing this survey you are giving your implied/passive consent to participate in the survey. A potential discomfort may include you feeling uncomfortable with some of the questions being asked if they are sensitive or evocative. If you feel uncomfortable, you may choose not to answer a question. The survey does not collect information about your name or email address and responses will be presented in group format only. This survey will be distributed through our collaborating partner’s networks, memberships and email listservs; in the past, similar surveys have resulted in 2,000 respondents. If you have any questions about this study, please contact Dr. Mark Tremblay at 613-737-7600 ext. 4114 or firstname.lastname@example.org. The Children’s Hospital of Eastern Ontario (CHEO) Research Ethics Board (REB) has reviewed this protocol. The REB considers ethical aspects of all research studies involving human participants at the CHEO and its Research Institute. If you have any questions about your rights as a study participant, you may contact the CHEO REB Chairperson at 613-737-7600 ext. 3624.
Note: Canada’s Integrated 24-Hour Movement Behaviour Guidelines for Children and Youth is in draft form and is not intended for general circulation.
Click on the link below for more information on the survey and instructions on how to get started. Thanks for your time!
We encourage you to circulate the survey link to your colleagues and among your networks. This stakeholder survey will be open until 12 p.m. EST on December 18th, 2015.
Today’s post comes from PhD student Calum Leask, describing his new paper, which is available here. You can find more on Calum at the bottom of this post.
Spending too long sedentary is associated with a multitude of physical and mental health risks. Of all sub-groups, older adults are the most sedentary and spend an average of 8.5 hours a day sitting down. Everybody is living longer now than ever before and therefore, it is important to make sure that these additional years can be as healthy as possible. One simple way this can be done is by reducing the amount of time spent sitting and interrupt prolonged (>60 mins) seated periods. Depending on the context of older adults’ sitting (for example what, when, where and with whom are these periods occurring), some sedentary bouts may be easier / more difficult to break up. Therefore, gaining this information may provide valuable guidance for future research. This is one of the first studies to explore the context of sedentary behaviour in older adults using objective measures (an activity monitor and wearable camera) and this study formed the first stage of my PhD research. The study was co-authored by Juliet Harvey, Professor Dawn Skelton and Dr Sebastien Chastin at the Institute of Applied Health Research in Glasgow Caledonian University.
For this study, 36 older adults (13 male and 23 female) were recruited and wore an activity monitor and timelapse camera for between 1 and 7 days. Participants had a mean age of 73 years and were recruited from the Glasgow Caledonian University Older Adult Volunteer Research Database. The activity monitor was attached to the individuals’ leg and detected both movement and posture in order to identify the periods in which participants were sedentary. The timelapse camera was worn on a lanyard around the participants’ neck and automatically captured an image of the physical environment from a first person perspective when a change in light or temperature was detected. The images taken during the sedentary periods identified by the activity monitor were then examined using an international classification system (SITONAUMY) to describe what, where, when, why and with whom the sedentary periods were occurring. The concept of using the activity monitor and camera images in combination is visible below.
In total, 52 days of data from 36 participants were available for analysis. Participants spent the majority of their sedentary time (70.1% at home) and 22.9% of their non-screen sedentary behaviour reading. Whilst the deleterious effects of sitting too much have already been discussed, activities like reading are cognitively stimulating and facilitate cognitive function, especially during aging. Therefore, it should be questioned whether future interventions should target these periods, or solely focus on sedentary activities which are cognitively passive.
A large portion of older adults’ sedentary time (56.9%) was spent alone. Loneliness increases the risk of prolonging sedentary time in this population; therefore older adults living alone may be an important sub-group to specifically target in future interventions. The social sedentary activities which this sample participated in were prolonged (18% of sedentary time) yet infrequent (6.9% of sedentary bouts). Socialising, like reading, has a mental health benefit, therefore it may be suggested that sedentary activities in specific contexts should be targeted, as opposed to generically aiming to reduce sedentary behaviour.
Whilst this study was conducted on a relatively small convenience sample, some of the results, including average daily sedentary time (14.2 hours) and television viewing time (4.3 hours), compare favourably to larger previously published works. Although using objective measurement (as conducted here) has been shown as more accurate than subjective means, the assessment is quite costly and due to the vast amount of data collected, requires intensive data processing and coding. However, the findings provide detailed insight into the context of older adults’ sedentary behaviour and provide specific guidelines for future interventions, although these results should be confirmed in a larger and representative population of older adults.
The full text may be found here: http://www.eurapa.net/content/12/1/4
Calum Leask is a PhD Student in the School of Health and Life Sciences at Glasgow Caledonian University, Scotland. His research focuses on reducing sedentary behaviour in older adults and more specifically, developing strategies to help older adults identify and reduce prolonged seated periods. For further information, please contact: email@example.com
The journal Measurement in Physical Education and Exercise Science is pleased to announce the publication of the new Special Issue on the measurement of sedentary behaviour (title: “Don’t Just Sit There – Do Something!“). The Special Issue is open for free access until the end of 2015.
A press release describing the new issue can be found here.
Today’s post comes from Dr. Olaf Verschuren, of the Centre of Excellence for Rehabilitation Medicine in Utrecht.
Children with cerebral palsy and adults with stroke are advised to participate in moderate to vigorous physical activity (MVPA), such as brisk walking and running. However, these patient groups develop or return to an inactive lifestyle due to the different physical, cognitive and environmental barriers, and often become deconditioned and predisposed to a sedentary lifestyle that may contribute to an increased risk for their health.
As we all know, prolonged periods of sedentary behavior are associated with several metabolic risk factors and all-cause mortality, independent of participation in physical activity. Therefore, people with stroke and children with cerebral palsy should not only participate in physical activity but also try to reduce or break up sedentary time as this might reduce the high risk of health problems. However, there is a lack of knowledge about sedentary behavior in these patient groups.
The SBRN defined ‘‘sedentary’’ as any waking behaviour characterized by an energy expenditure ≤1.5 metabolic equivalent of task (MET) while in a sitting or reclining posture. Despite sitting being an omnipresent behavior in all people, there are no studies actually assessing the energy expenditure of sitting and standing in people with stroke and children with cerebral palsy. So, in order to be able to support people with stroke and children with cerebral palsy to engage in activities that generate light to moderate intensity energy expenditure (that exceeds the 1.5 METs) and confer some health benefit, it is necessary to know which activities generate the required physiological response. Thus, when operationalizing sedentary behavior against low intensity physical activities such as sitting, standing and walking, we have to rely on the energy expenditure.
Olaf Verschuren (researcher at the Brain Center Rudolf Magnus and Center of Excellence for Rehabilitation Medicine, University Medical Center Utrecht and De Hoogstraat Rehabilitation, in Utrecht, The Netherlands) and colleagues recently published two studies that objectively measured and calculated the energy expended by people with stroke and children with cerebral palsy during near sedentary behaviors.
The main findings:
- Children and adolescents with cerebral palsy across all functional had energy expenditures higher than 1.5 METs during standing. Our findings related to energy expenditure therefore suggest that changing children’s position to a standing position may contribute to the accumulation of light activity and reduce sedentary behavior. See Figure 1.
- The findings of the study in people with stroke demonstrate that the energy expenditure during typical sedentary behaviors (sitting supported and unsupported is very narrowly bounded around 1.0 METs. Energy expenditure during sitting and standing was ≤1.5 METs for almost all functional levels. Independent wheelchair propulsion and walking seem to be light activities (≥1.5 METs) that could be used by people with stroke to interrupt sedentary behavior. See Figure 2.
Verschuren, Olaf, et al. “Muscle activation and energy-requirements for varying postures in children and adolescents with cerebral palsy.” The Journal of pediatrics 165.5 (2014): 1011-1016.
Verschuren, Olaf, et al. “Characterizing energy expenditure during sedentary behavior after stroke.” Archives of Physical Medicine and Rehabilitation (2015).