Time to combine physical activity, sedentary behaviour and sleep guidelines into one holistic guideline?

Sitting is bad for you.  Exercise is good for you.  Sleep is too.

At present, we have 3 separate guidelines targeting these 3 separate behaviours.  However, when combined these behaviours make up the full 24 hour period, so it seems a bit strange to separate them out into separate and distinct constructs, especially since they all interact and influence each other (e.g. more screen time means less sleep, more activity means more sleep, more sleep means more activity, etc).  As a result, Canada is in the process of creating guidelines which integrate sleep, activity, and sedentary behaviour to give more holistic and less fractured advice to the public/policymakers/physicians/etc.

I’ve spent the past 3 days at a meeting learning about the development of these new guidelines, and I think they are a very interesting and relevant idea.  Drs JP Chaput, Val Carson, Casey Gray and Mark Tremblay (full disclosure: friends and colleagues all) have recently released a commentary outlining the rationale for these new guidelines, which has been published in the International Journal of Environmental Research and Public Health. The article has an open access license, so I have included it in full below.  It’s only a couple typed pages long, and worth the read.

I’m interested to hear what people think of this idea, as I think it represents a very different approach to thinking about activity/inactivity than has been employed in the past.


1. Introduction

Human movement has been a necessity for survival throughout evolution. However, sitting has become the new norm in today’s environment despite the fact that we have not genetically adapted to this sedentary lifestyle (1). It is now common to refer to physical activity as having “health benefits”, even though the active state is the normal biological condition for metabolic processes (2,3). Lack of human movement should rather be perceived as “abnormal” and associated with numerous health risks (4,5).

Physical inactivity and childhood obesity represent pervasive, and arguably the greatest, health challenges to our children today (6,7). There is no easy solution to these serious public health threats and they need to be addressed by a range of strategies to maximize success. One of the strategies is to find ways to increase overall physical activity of children. However, health research has mainly focused on the impact of moderate-to-vigorous physical activity (MVPA), or even high-intensity physical activity, on various health outcomes. Although this approach has resulted in important contributions to the field, emerging evidence indicates that a broader, more inclusive and more integrated approach to understanding and promoting human movement is required to better address the current public health crisis of physical inactivity and childhood obesity.

There is no doubt that MVPA provides many important health benefits. However, MVPA only accounts for a small proportion (<5%) of the 24 hour day, even among active children and youth. In contrast, sleep (~40%), sedentary behavior (~40%) and LPA (~15%) make up approximately 95% of the day (Figure 1). Ignoring other components of the movement continuum while focusing efforts on MVPA limits our understanding of how habitual movement behaviors interact to impact children’s health. Indeed, recent efforts to address the single-minded focus on MVPA have led to a proliferation of sedentary behavior research and to the creation of the world’s first sedentary behavior guidelines for children and youth (8-10).

There is accumulating evidence that excessive sedentary behavior, particularly screen-based sedentary behavior (e.g. television viewing), has unfavorable effects on various health indicators, independent of MVPA (8,9). Likewise, short sleep duration is associated with many adverse health outcomes including obesity, type 2 diabetes, depression, suicidal ideation, and poor academic performance (11-14). This issue is of particular concern since a decrease in sleep duration has been observed over the past decades in children and adolescents (15,16). Finally, a growing body of evidence indicates that spending more waking hours in LPA compared to sedentary pursuits can provide health benefits (17-19). Reallocating sedentary time to LPA (e.g. TV watching to active play) is of substantial public health interest given that it is not feasible to participate in MVPA during all waking hours. Breaking up sedentary time with LPA is a more achievable and viable goal for increasing movement (i.e. number of steps per day) and acquiring associated health benefits than focusing solely on MVPA. However, current physical activity guidelines only focus on MVPA (and recently sedentary behavior) and do not take into consideration other important movement/non-movement behaviors that occur throughout the day. This issue is important because having one “unhealthy” movement behavior can moderate the health benefits of another. For example, the health benefits of MVPA can be mitigated if children have poor sleep habits and/or engage in excessive sedentary behavior (20). Conversely, increased physical activity could well decrease the detrimental effects of insufficient sleep and/or extended periods of sitting in some individuals (21,22).

Figure 1. Estimated distribution of movement behaviors over the 24 hour period.

2. Is there a need for 24 hour movement behavior guidelines?

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Category: News, Obesity Research, Peer Reviewed Research, Physical Activity, Sedentary Behaviour | 1 Comment

Drinking coffee during pregnancy associated with obesity in offspring

pregnant coffeeIn 1992, David Barker suggested that many chronic diseases are the result of physiological processes initiated between our conception and our birth. The key feature of this model is that intrauterine environmental exposures and events affect fetal development, and may increase the risk of specific diseases in adult life.

For instance, you may have heard of the thrifty phenotype hypothesis. The thinking goes as follows: poor nutritional conditions in utero initiate metabolic adjustments to prepare the unborn fetus for survival in an environment in short supply of nutrients. However, when such a fetus is then born to an environment of plentiful supply of nutrients, this maladaptation increases their susceptibility to disease. In other words, any factor which reduces fetal growth tends to be associated with a number of chronic conditions later in life, such as coronary heart disease, stroke, diabetes, and hypertension.

Caffeine is one the most widely consumed substances in the world. For instance, over three-quarters of pregnant women in the US report consuming caffeine. Prior studies have suggested that caffeine intake by pregnant women can result in an increased risk of miscarriage, fetal death and impaired neurological development. More recently, human studies have shown that in utero caffeine exposure is associated with increased risk of abnormal fetal growth including small-for-gestational-age. Small-for-gestational-age has been associated with higher risk of obesity and metabolic syndrome after birth.

This indirect link between maternal caffeine intake and offspring obesity prompted Li and colleagues to assess the relationship in a prospective study of 829 pregnant women with 15 years follow-up of their offspring. Maternal caffeine intake was prospectively assessed during pregnancy while outcome measures, such as offspring BMI were retrieved from medical charts of the children. The analyses controlled for a number of potential confounders, including maternal prepregnancy BMI, race/ethnicity, diabetes, smoking during pregnancy, and absence of breastfeeding, among many others.

What did the authors find?
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How many calories do you burn by laughing?

laughterI have been drawn to sketch comedy since my early teens. I religiously watched every episode of In Living Colour and Saturday Night Live (SNL) and subsequently tried to re-enact some of the scenes and characters with my friends. During high school, my friends and I would dream about being SNL writers when we grew up, spending many math classes giggling over some ridiculous sketch idea we came up with. As an adult, my obsession with Saturday Night Live has not waned. While I have tried (unsuccessfully) to get tickets to the live show for a number of years, the closest I’ve come to checking that item off my bucket list was during a tour of the SNL studio while on a recent NYC visit.

This summer, while traveling through Africa (and planning on reading literature more germane to where I was travelling), I got hooked on Live From New York, a highly detailed account of SNL’s long history. In that voluminous book (760 pages) I learned that many of my favourite comedians who at one time or another graced the SNL stage, including the likes of Dan Aykroyd, Mike Myers, Chris Farley, Amy Poehler, and Tina Fey, honed their art at The Second City comedy club. As soon as we were back in Toronto, I enrolled myself into the improv comedy program at Second City.

I have been taking 3-hour classes with 18 other brave souls every weekend for the past month and a half. And it has been an absolute blast. On many occasions, I come home after class with my jaw sore from laughing so much. But I’ve also come home quite hungry and exhausted, which got me thinking: how many calories do we burn when busting a gut over something hilarious?
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Exercise physiologist needed

The Department of Applied Human Sciences at the University of Prince Edward Island is looking for a CSEP Certified Personal Trainer or Certified Exercise Physiologist to coordinate labs in biomechanics and exercise physiology this winter (a BSc is required, an MSc is an asset).

Details here.

If you know anyone in Atlantic Canada (or who wants to move to Atlantic Canada) with those qualifications, please encourage them to apply.



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What day of the week do you weigh the most?

Weight FluctuationMonday. According to a recent study by Orsama and colleagues, that’s the day when most people experience their maximum body weight. And your lowest body weight? That’s most likely to be recorded on Friday.

The weekend certainly seems to play some havoc on our energy balance.

The 7 day week cycle has an impact on many of our behaviors. Take sleep, for example. During the week, we get up regularly at the sound of our alarm, but come Saturday, the alarm clock may be turned off and you allow yourself to sleep in. Your physical activity level is also likely to oscillate based on the day; individuals who actively commute to work may become more of a couch potato on the weekend. People may also be more likely to go out and have a few drinks over the weekend. All these behaviors can have an impact on a person’s energy balance, and subtly, on their body weight. And apparently, that’s exactly what happens.

In the study published earlier this year, Orsama and colleagues explored the weekly rhythm of weight to understand the normal variation of weight which occurs during the week. The researchers analysed daily self-reported body weight in 80 adults (BMI: 20.0–33.5 kg/m2; age: 25–62 years). To avoid intra-day variation in body weight individuals were instructed to record their daily weight immediately after waking up and before breakfast. The length of each individual’s time series of recorded weight varied from 15 to 330 days.
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Economists should focus on the economy, not public health

We get it.  Maclean’s Editor-at-Large Peter Shawn Taylor thinks that public health people (e.g. myself) should stay away from chronic disease (I guess it’s time to wrap up my research program and call it a career!).  And he thinks that we should definitely stay away from any policies related to chronic disease that have anything to do with personal choice or the economy.

Earlier this month I sounded off on a recent Maclean’s editorial arguing that public health should prioritize infectious diseases like Ebola, rather than chronic diseases like cancer or obesity.  This week, Mr Taylor repeated the same arguments in an opinion piece for the Globe and Mail concluding that:

It is not the job of public health to have an opinion on taxes, economic policy, free trade or corporate control. Neither should it be their business to interfere in the freely-made choices of adults.

Public health ought to stick to their needles, and leave the economy alone.

To recap: Mr Taylor (an economist and journalist) is well equipped to tell public health agencies how to run their business.  Those of us trained in health research are not (one presumes it is because we are not economists).  The level of condescension implicit in that line of reasoning is nothing short of astounding (if I ever meet Mr Taylor, I hope to ask him what he thinks of health economists… does their economic training qualify them to speak on important matters of public health, or are they disqualified by their training in public health?).
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