Laird Harrison

June 07, 2016

BOSTON — Contrary to enthusiastic reports in the media, standing at a desk burns only about 12% more energy than sitting, new research shows.

"Short walks are going to give you the biggest bang for the buck," Bethany Barone Gibbs, PhD, from the University of Pittsburgh, said here at the American College of Sports Medicine 2016 Annual Meeting.

Epidemiologic studies on risks related to sitting have captured a lot of attention in recent years. In particular, reports that sitting can increase mortality, even in people who exercise regularly, have raised concerns.

And they have fueled the popularity of desks that allow users to either sit or stand, said Dr Gibbs.

Just how much more energy it takes to stand instead of sit matters because the average American is burning about 100 fewer kilocalories per day at work now than 40 years ago, she explained, citing data from the Bureau of Labor Statistics.

According to a recent estimate, 90% of Americans could stop gaining weight if they increased their energy expenditure by those same 100 kcal per day, she pointed out (J Am Diet Assoc. 2009;109:1848-1853).

Standing desks might be a simple way to burn those calories. In a report published last year in the Wall Street Journal, standing for 4 hours was said to burn 240 kcal more than sitting.

Counting Calories

A "calorie calculator" on JustStand.org produced a more moderate estimate — a difference of 150 kcal between standing and sitting for 4 hours. But even that didn't seem quite right, said Dr Gibbs. "We thought the numbers looked a little high."

To test these estimates, the researchers used indirect calorimetry with a metabolic cart (Vmax Encore; Becton, Dickinson and Company) to measure energy expenditure in 18 adults interested in buying sit–stand desks.

Half the participants were men and half were women. Average age was 39 years, average weight was 75.7 kg, and average body mass index was 27.3 kg/m².

The researchers assessed study participants performing tasks such as copying definitions from dictionaries in simulated work situations as they sat continuously, stood for 30 minutes and then sat for 30 minutes, stood continuously, and sat for 30 minutes and then took a 2-minute walk at a self-selected pace.

 
I believe in it personally, but I don't think the evidence is there.
 

For a 60 kg person, sitting and standing burned only 0.071 kcal/kg more per hour than continuous sitting — an increase of 7.5% (< .001). Continuous standing burned 0.106 kcal/kg more per hour than continuous sitting — an increase of 11.5%. Sitting with a periodic walk was most beneficial, burning 0.222 kcal/kg more per hour than continuous sitting — an increase of 23.5% (< .001).

Extrapolating over an 8-hour work day for a 60 kg person would mean that sitting and standing would burn 43 kcal more than continuous sitting, and sitting and walking would burn 107 kcal more than continuous sitting.

A combination of standing and walking could increase energy expenditure in an 8-hour day by 177 kcal for an average-sized woman and by 208 kcal for an average-sized man, Dr Gibbs reported.

The higher estimates reported in the media could have come from studies that used heart rate, a less accurate approach than indirect calorimetry, she explained.

Some previous research has suggested that people who stand more at work sit more when they are not working, she pointed out. Still, the finding doesn't mean sit–stand desks are worthless, said Dr Gibbs, who uses one herself.

Some previous small studies have shown that people report feeling more positive and productive when they stand up at work, she said. "I believe in it personally, but I don't think the evidence is there," she told Medscape Medical News.

Dr Gibbs and her colleagues did not test treadmill desks, which allow people to walk while working. "Of course, walking on a treadmill is going to give you a way better health benefit," she said. "But a sit–stand desk is more easily integrated into the American workplace."

After the presentation, James Betts, PhD, from the University of Bath in the United Kingdom, asked whether the researchers had taken into account how much the participants moved around while sitting.

"We were measuring their productivity, so it was not a natural environment," Dr Gibbs explained. "They did not move around much."

A series of other studies presented during the session examined sitting from other perspectives.

Results from a randomized controlled trial were presented that showed that 4 days of prolonged sitting abolished the benefits of a 1-hour bout of exercise to attenuate postprandial plasma triglycerides.

This was true regardless of whether the participants were taking in more calories than they were burning, said Edward Coyle, PhD, and Il-Young Kim, PhD, from the University of Texas at Austin, who presented the research.

But an epidemiologic study suggested that prolonged sitting only slightly increased the mortality rate of people who exercise regularly and are not obese.

The research so far leaves many questions about the relation between sitting and exercising, said Peter Katzmarzyk, PhD, from the Pennington Biomedical Research Center in Baton Rough, Louisiana, who presented the results.

For now, the bottom line is that clinicians should encourage their patients to exercise, regardless of whether they are standing up at work, said session moderator Renee Rogers, PhD, from the University of Pittsburgh.

Standing has benefits, but "it's a continuum, a spectrum," she told Medscape Medical News. "Standing may not be enough in terms of the public health message that we're sending."

The study presented by Dr Gibbs was funded by a grant from HumanScale. Dr Gibbs, Dr Coyle, Dr Kim, and Dr Katzmarzyk have disclosed no relevant financial relationships. Dr Rogers reports receiving a grant from Weight Watchers.

American College of Sports Medicine (ACSM) 2016 Annual Meeting: Abstract 1723. Presented June 2, 2016.

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