Office Workers Sit Less With Intervention, Up Muscle Mass

Becky McCall

May 02, 2016

A multicomponent office-based intervention reduced sitting time in office workers and was associated with a lowering of body-fat percentage, shows a study that adds to a growing but inconclusive evidence base for the effects of sitting on health.

At 1 month, sitting time was reduced by 71 minutes in an 8-hour working day and was primarily replaced by standing time. In addition, the number of prolonged sitting periods dropped and sit-to-stand transitions increased — for example, by walking to talk to a colleague rather than emailing them, report the researchers, led by Ida Danquah, a PhD student from the University of Southern Denmark, Copenhagen.

The cluster randomized controlled trial — entitled Take a Stand! — included 317 office workers in 19 offices across Denmark and Greenland and is currently the largest of its kind conducted in the office environment among nonhealthcare workers. Findings are published online April 19 in the International Journal of Epidemiology.

Ms Danquah highlighted the fact that intervening in the workplace targets a cohesive group of workers who can support each other, unlike in the isolated environment of the home. The intervention was also designed to minimally disrupt the working day.

"We deliberately didn't tell them to go jogging during work time. They mainly changed from sitting to standing and walking while still doing required tasks," she told Medscape Medical News in an interview.

Coauthor Janne Tolstrup, PhD, also from the University of Southern Denmark, commented on the potential health effects related to less sitting time, noting that the findings, "in the long run, could be associated with reduced risk of heart diseases, diabetes, and all-cause mortality, especially among those who are inactive in their leisure time."

However, the researchers appreciate that the value of the intervention really lies in its sustainability, and they are quick to note that the study lasted for only 3 months, pointing out that "future research should address factors that sustain the reduction in sitting time."

And asked to comment, Richard Pulsford, PhD, from the University of Exeter, United Kingdom, acknowledged the benefit of a minimally disruptive workplace intervention but agreed that "it remains to be seen whether even comprehensive multiple-component workplace interventions can bring about sustainable change in workplace activity/inactivity behavior."

Likewise, Nipun Shrestha, MD, from the Health Research and Social Development Forum, Nepal, who recently conducted a Cochrane Review on sitting at work, published in March (Cochrane Database Syst Rev. 2016;3:CD010912), reflected that, regarding sustainability of the intervention in the current study, "there is a decrease in effectiveness at 3 months compared with 1-month follow-up."

Multicomponent Intervention to Reduce Sitting Time

In total, four workplaces (municipal organizations and one bank) comprising 19 offices were cluster-randomized (1:1) to intervention or control. The intervention comprised a combination of local environmental changes, as well as a lecture and workshop, and to help with implementation and motivation, the support of local ambassadors and management was enlisted.

Sitting time was measured at 1 and 3 months using an activity-measuring device attached to each participant's thigh. Data were collected on time spent sitting, standing, or other activities. Control participants were instructed to behave as usual.

The researchers found that total sitting time was 71 minutes less per working day at 1 month (P < .001), and 48 minutes less at 3 months (P < .001) in the intervention group compared with the control group.

Also at 1 month, the number of prolonged sitting periods (30 minutes or more) was lower (-0.79 per 8-hour workday, P < .001), and sit-to-stand transitions were higher (+14%/sitting hour, P = .001) in the intervention vs control groups, respectively. A similar pattern was found at 3 months.

Body-Fat Reduction

Body-fat percentage over 3 months was 0.61% lower in participants in the intervention group compared with the control group (P = .011). The 0.61% drop in body-fat percentage was due to an increase in fat-free mass of 0.79 kg.

Asked whether this small change in body fat was significant, Ms Danquah said, "The overall aim of this type of intervention is to ultimately protect against coronary heart disease. Body-fat percentage could be a marker for this."

However, Dr Pulsford explained that there was no reduction in body fat per se in the study; rather, an increase in muscle (fat-free mass) led to a slight reduction in percentage of body fat, which he noted is an important distinction

"This increase in fat-free mass is perhaps not surprising given the increased daily activity of large muscle groups involved in the higher number of sit/stand transitions and daily walking in the intervention group."

Dr Shrestha added that if the activity that replaced sitting were just standing, "then 48 minutes would not cause any reduction in body-fat percentage, as there is hardly any difference in energy expenditure between sitting and standing."

Sit-Stand Desks Commonplace in Scandinavia

Sit-stand desks are commonplace in Scandinavian offices and in particular, this trial included workers who already had redundant sit-stand desks and aimed to test whether the intervention encouraged greater use of these desks, which it did.

"Because nearly all offices in Denmark have these desks, people could just use what they already had, and they did," Ms Danquah pointed out.

The recent Cochrane Review assessed the health benefits of sit-stand desks by reviewing 20 studies. Six of the studies provided evidence suggesting that users of sit-stand desks sat between 30 minutes and 2 hours less, compared with when they used conventional desks during the working day.

Is Sitting Really "the New Smoking"?

Although sitting has been described by some researchers as "the new smoking," it is still too early to draw concrete conclusions, due to mixed findings in studies examining the issue.

A meta-analysis reported by Medscape Medical News last year claimed that prolonged sitting was associated with higher mortality from all causes.

However, a 16-year study, also from 2015, found that sitting per se, irrespective of physical activity, is not associated with risk of death. Those authors suggested policy makers be "cautious about placing emphasis on sitting behavior as a risk factor for mortality that is distinct from the effect of physical activity."

Sustainability of Reduced Sitting-Time Interventions

The study led by Ms Danquah was carried out 2 years ago, and since then she and her colleagues have asked some of the participants whether they continue to make behavioral changes to sitting time while at work.

"Of course, people are back to some of the old habits, but also people are standing and walking more and are having more breaks in their day," she said.

She emphasized that this study had a short duration, and effective change would take time. "Change is likely to be incremental as people start seeing the benefits. We also found that if office workers saw one person raise their desk then another might raise their desk, too — it spreads in the office environment."

Many offices that participated in the trial intend to continue with the intervention.

"In one municipality workplace, they plan to spread the intervention to the entire workplace later this year," Ms Danquah noted.

This work was supported by Tryg Fonden, Denmark. The study authors have no relevant financial relationships, nor do Dr Shrestha and Dr Pulsford.

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Int J Epidemiol. Published online April 29, 2016. Abstract


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