Standing desks played part in cutting office workers' sitting time by an hour a day: The BMJ
Office workers who used standing desks reduced their sitting time by about an hour a day over one year, according to the results of a randomised control trial (RCT). The first author of a paper based on the study, which appears in today’s edition of The BMJ, is Charlotte Edwardson, associate professor of physical activity, sedentary behaviour and health at the University of Leicester’s department of health sciences.
As well as the standing desks, the office workers received a package of measures to encourage them to move more and sit less. Sitting less was also linked to minor improvements in stress, wellbeing, and energy levels at work – although these improvements were not deemed to be clinically meaningful.
Dr Edwardson was one of a team of researchers based in the UK and Australia that evaluated the impact of an intervention called SMART Work & Life (SWAL). Its aim is to reduce sitting time and increase moving time at work – with and without a standing desk – delivered by ‘workplace champions’.
Three control groups in RCT
The trial involved 756 office workers from two councils in Leicester, three in Greater Manchester and one in Liverpool. Participants were randomly assigned to the SWAL intervention, the SWAL intervention with a standing desk, or a control group (working as usual) over a 12-month period.
The average age of participants was 45, 72 per cent of whom were women and 75 per cent were white British; most (85 per cent) worked full time. The participants’ average body mass index (BMI) at the start of the study was 26.5.
Members of the SWAL intervention group received resources to help them reduce their sitting time and which highlighted the health risks of sitting for too long. Workplaces were also encouraged to make small changes around the office to enable more movement – such as relocating printers and wastepaper bins and creating standing areas for meetings.
Those in the SWAL plus desk group also received a height adjustable desk to encourage less sitting time while their counterparts in the control group worked as usual. Workers’ sitting time was measured using an accelerometer device, which was worn on the thigh at the onset of the study and again at 12 months. Daily physical activity levels, and self-reported feedback about work, physical and mental health were also recorded.
The SWAL intervention plus standing desk was three times more effective at reducing sitting time than the SWAL intervention alone. For example, at 12 months, daily sitting time for the SWAL group, and the SWAL plus standing desk were, respectively, 22 minutes and 64 a day minutes lower on average than the control group.
Possibility of 'reporting bias'
Small, but non-clinically meaningful improvements in stress, wellbeing, and a sense of work-related vigour were found for both intervention groups compared with the control group at three and 12 months, as well as lower limb pain (hips, knees and ankles) in the SWAL plus desk group.
Although time spent sitting was lower in both intervention groups compared with the control group, the researchers state that most participants simply replaced sitting with standing, and that say further work is needed to encourage more physical activity, particularly outside of working hours.
Dr Edwardson and her colleagues acknowledge that their study had some limitations. For example, knew the purpose of the device measuring their movement and this could have affected their behaviour. They could also have been selective in their responses to questionnaires – a phenomenon known as ‘reporting bias.’
The researchers state that both SWAL and SWAL plus desk were associated with a reduction in sitting time, although the addition of a height adjustable desk was found to be three times more effective.
Sedentary behaviours and home working
The findings are noteworthy because they come from a fully powered cluster randomised trial with objective measurement of sedentary behaviour at three and 12 months [Cindy Gray]
In a linked editorial, Cindy Gray, from the University of Glasgow's school of social and political sciences, said: ‘The findings are noteworthy because they come from a fully powered cluster randomised trial with objective measurement of sedentary behaviour at three and 12 months.’
However, Professor Gray pointed out that the move to more home-based and blended patterns of working after the Covid-19 pandemic is likely to increase sedentary behaviours in the workforce. Therefore, she says ‘understanding how to optimise occupational interventions to support people to sit less and move more around their home during both work and non-working hours
A growing body of evidence indicates that sedentary lifestyles are associated with higher levels of chronic disease, including heart diseases, type 2 diabetes, some cancers, and higher rates of depression and anxiety.
Office-based workers are one of the most sedentary populations – spending 73 per cent of their workday and 66 per cent of their waking day sitting – but studies looking at ways to reduce sitting in the workplace have been deemed low quality.
To read the full version of the article, titled Effectiveness of an intervention for reducing sitting time and improving health in office workers: three arm cluster randomised controlled trial, visit: https://www.bmj.com/content/378/bmj-2021-069288
To see the editorial, titled: The importance of sitting less and moving more, visit: https://www.bmj.com/content/378/bmj.o1931Author: Ian A McMillan