Breaks in Sedentary Time

There are two, no three, disease or health related lifestyle factors that I pay the most attention to when scanning research updates: dietary intake, tobacco use and sedentary behavior.  Sedentary behavior is any activity that keeps the body relatively still, e.g., sitting  and- typing a blog post, watching TV, playing cards, reading a book, listening to an instructor/speaker, playing video games.  Past research has shown that the more a person sits the worse it is for their health, with health defined as all-cause mortality, chronic disease, metabolic dysfunction (high blood pressure, blood sugar, etc.).  I have already talked about the past studies, but to review (and I don’t recall who was in the sample studied, i.e., men, women, young, old, black, white), sitting for more than an hour without taking a break -getting up and moving - is associated with poor health outcomes and this is still true (with a weaker effect) if the person doing the uninterrupted sitting also exercises for an hour or so a day.  So physical activity is good, sedentary behavior is bad, and sedentary behavior is bad (deleterious) for inactive AND active people.

So that was old news.  This week I read another study about the benefits of breaking up sedentary time.  The study by Sardinha, Santos, Silva, Baptista, & Owen (2014) specifically focused on Portuguese adults between the ages of 65 and 94, but it is likely that the same metabolic processes happen in older adults of other races/nationalities though the effect may be higher or lower.  An example; if sedentary behavior increased the risk of all-cause mortality by 2% in one group, it would probably increase the risk in a similar group, but the increase (effect) might be 1% or 5% instead.  Sedentary behavior is still bad, just more or less so.

The current study was a little different from those that came before, and that is a good thing, because it makes the evidence stronger.  Here the researchers included measures specific to an older person’s physical activity level, physical functioning and physical independence.  The participants wore accelerometers on their hips during the day for four days.  The accelerators recorded information on movement that the researchers could turn into activity levels.  The researchers took several measures of physical functioning, including, how many times a person could sit and stand from a chair in 30sec, how many dumbbell curls they could do in 30sec, and how far they could walk in 6 minutes.  The researchers measured physical independence with a 12 item scale with a total of 0 to 24 points.  Items include questions about one’s ability to do an activity with or without assistance, e.g., bathe, do laundry, walk, etc.  I found an example of both tests, if you’d like to see them click here for the physical function test and here for independence test.

For the outcome of interest, Sardinha et al focused on differences in persons’ physical functioning abilities (e.g., the dumbbell activity) and a score that totaled all those physical function abilities. These measures matter because they are important indicators of successful vs usual aging.  Sardinha et al compared the functional measures, while controlling for persons’ physical activity levels (do they get the recommend 30 minutes a day of moderate to vigorous physical activity/ yes or no; based on the accelerometer data), independence test scores (described in the above paragraph), BMI, sex and some other things.  They wanted to see if peoples’ scores were different based on the amount of time they spent in sedentary behavior (sb) and whether or not that time is broken up; breaks in sedentary behavior (BST).

And of course, the scores were different.  In the analysis of the physical function components and the overall score, there were higher scores in the dumbbell curl, the chair test and the overall score, when people took breaks in their sedentary time. The researchers also looked at the direct and independent effect of moderate-vigorous physical activity (cycling, aerobics, running), sedentary time and breaks in sedentary time on the total physical function score and found that people who engage in at least 30 min of moderate to vigorous physical activity a day have higher scores, people who spend the most time in sedentary behavior have the lowest scores and those who take breaks have higher scores than those who do not.

I leave you with a quote from the authors’ conclusion section:

Therefore, PA [physical activity] guidelines for older adults might emphasize more strongly these two distinct behaviors to be considered together, such that even if a person were to comply with 30 min/d of MVPA, they should avoid too much sitting for the rest of the day. Periodic and small interruptions to SB [sedentary behavior] are likely to be of importance in preventing a decline in physical function.

Sardinha, L. B., Santos, D. A., Silva, A. M., Baptista, F., & Owen, N. (2014). Breaking-up Sedentary Time Is Associated With Physical Function in Older Adults. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, glu193.

What's the story behind the calories + activity labels for soda?

Another study meant to test the effect of providing nutrition information at the point of sale has been published in a respected peer reviewed journal.  In addition, the results of the study are reported in the popular press and as often occurs, the popular press is reporting selectively.  It’s unfortunate that reporters would be selective or misrepresentative because the actual findings are impressive without embellishment or obfuscation. 

Here it is in a nutshell.  In 2012/2013, Sara Bleich and colleagues Barry, Gary-Webb and Herring conducted a study in Baltimore, MD. They introduced 4 beverage related nutrition disclosures (or treatments) to a small sample (n=6) of corner stores that were in walking distance to nearby middle and high schools. All 6 stores received each of the 4 nutrition treatments for about two weeks– but in random order.  The nutrition disclosures, which were placed on signs on beverage cases were 1) Did you know that a bottle of soda or fruit juice has about 250 calories? Or 2) Did you know that a bottle of soda or fruit juice has about 16 teaspoons of sugar? Or 3) Did you know that working off a bottle of soda or fruit juice takes about 50 minutes of running? Or, 4) Did you know that working off a bottle of soda or fruit juice takes about 5 miles of walking?  [Note that the exercise examples are not equivalent, a flaw the researchers note in the limitations section of their paper.  Why does it matter?  People may not know how long it takes them to walk five miles, for me it would be more than 90 minutes.  In addition, the calorie expenditure data was based on a male or female adolescent weighing about 110 pounds.  The individualistic nature of calorie expenditure is one of the reasons I prefer multiple traffic light labels over exercise equivalents for an informative information disclosure.]  While the nutrition treatments were in place (i.e., the randomly selected sign was posted) research assistants collected sales receipts from a random sample of purchases at each store.  To be included in the random sample, the sales receipt had to be associated with someone who appeared to be between the ages of 12 and 18 and black.  This is important because the results of the study are generalizable to black adolescents in a Northeastern US city – not other kids, not adults, not other types of locations(e.g., a rural town).  The headlines in popular press do not make this distinction and only focus on one thing.  The headlines promulgate the findings that telling a person how much activity they will have to do to burn the calories in a soda or fruit juice leads to a change in the number of sugar sweetened beverages purchased, the size of sugar sweetened beverages purchased, and the average number of calories purchased. 

In the study, (see table 1 if you can access it) the average beverage calories sold when no information was posted was 207; the average calories sold during the calorie only treatment was 185; the teaspoons of sugar treatment, 188; the minutes of running treatment, 193; the minutes of walking treatment, 187.  In this analysis, for this outcome, the best treatment was the calorie only disclosure.  The average percent of sugar sweetened beverages purchased when no information was posted was 97%; for all of the different treatments the percent of sugar sweetened beverages purchased was between 88.3% and 89.1% - more than a 10% drop from the no information treatment, but similar across information types.  The purchase of sugar sweetened beverages greater than 16 ounces (recallthis post about the portion size cap) was around 53% when no information was posted and a much lower 38% with the calorie only treatment, 42.7% with the teaspoons of sugar treatment and 46.7% and 47.9% with the running and walking treatments, respectively.  As you can see, there is no earth shattering headline about exercise equivalents in the overall results of this study and in fact, the results are an exception to previous findings that calorie disclosures alone did not work.  However, in the analysis I just described, the types of disclosure or treatments were not directly compared to each other. 

In a sub analyses (with adjustment), the researchers did compare the treatments and found a significant (real) but modest (about 6 calories) superiority for the treatment that listed the number of miles it would take to walk off a bottle of soda or juice compared to the average across all treatment conditions.  For example, in the analysis of all the beverage sales,  the average calories sold for any information treatment was 184 (compared to 203 without information), but the average calories sold in the walking 5 miles treatment was 179.

During the last week of information disclosure, the researchers conducted exit surveys with a small group of randomly selected beverage customers (who were black adolescents). The surveys explored whether or not the youth saw, understood, believed and considered the information.  Please see the full article to read about the findings.¹

Lastly, and importantly, the researchers continued to track sales for 6 weeks after removing all of the nutrition signs.  They did this to test lasting effects and indeed all of the outcomes, though attenuated, remained in effect.

I am a researcher in this same area – though my focus is on nutrition labeling law. I understand that calorie only disclosures are not always effective or as effective as public health advocates would like them to be and I find the literature on multiple traffic light labeling more promising.  Others find the literature on exercise equivalents, to which the Bleich et al study belongs, to be equally or more promising.  So, I think that is what the press is capitalizing on – exercise equivalents did change behavior in this study, but the press isn’t doing a good job of telling the rest of the story.  In this sample of black youth, who as a population have a disproportionate prevalence of obesity and soda consumption, just providing a calorie disclosure at the point of sale led to positive changes in all outcomes.  That is GREAT news!   As the federal law now stands, the only disclosure mandated is calories and Bleich et al give us hope that even if we can’t modify the law's directive, nutrition labeling could still positively impact a high risk group.

¹Am J Public Health. Published online ahead of print October 16, 2014: e1–e8. doi:10.2105/AJPH.2014.302150

Rethink Butts.

For me, and perhaps many of you, no place soothes my soul more than the sea - specifically the shore.  I love the sand, the sun, the sound of the waves and the great, vast, body of water that looms before me.  I am protective of my beautiful place - of the earth in general  - and I most passionately and avidly promote tobacco free beaches, parks and trails.

If I could be responsible for passing one law - it would not be diet related - it would be one that led to Tobacco Free Beaches USA.

Today I heard a public service announcement from a Legacy Foundation and Leave No Trace Center for Outdoor Ethics partnership.  The PSA was launched over a year ago, in honor of Earth Day 2013.  I am sharing the PSA with you so you will consider joining in the effort to rid the earth of toxic cigarette waste.  If you are a smoker, I hope you are like many I see who respect the earth and dispose of their butts responsibly (i.e., not out the car window or on the ground).  {I have to add, if you are a smoker, quitting smoking is hard, but doable and it will change your life! Click here for help.}

Cigarette butts are not readily biodegradable; they don't break down and harmlessly evaporate into the air.  The filters breakdown (after many years) into particles of a harmful plastic compound and the chemical components are absorbed into the soil or worse, children and or animals (dogs, cats, fish, etc) come into contact with the discarded cigarettes and are poisoned by them. 

Please listen to the PSA by clicking on the arrow and to learn more, go to the rethinkbutts website here.