In the hot seat: why your chair is a health hazard

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Evidence suggests that prolonged sitting is a serious health hazard. Should office workers be worried?

“Our backs have become weaker over the last few decades – we just don’t use them as much as we used to,” says professor Daniel Lieberman. “Chairs with a seat back didn’t become common until the Industrial Revolution, before that unless you were a king or whatever, everyone else had stools or sat on the floor, and when you do that you have to use your back muscles constantly in order to support yourself. The fact we sit so much of the day...that has all kinds of fascinating effects on our posture and likelihood of getting back pain.”

Lieberman, Professor of Human and Evolutionary Biology at Harvard university, was interviewed on Changing World, Changing Bodies, a fascinating BBC World Service radio programme about how the decline of active work has led to the decline of our bodies and propensity for modern diseases like back pain.

Some doctors believe our back muscles have weakened due to prolonged sitting, a possible factor in back pain. Photograph: iStock

While at the start of the 19th century, just one per cent of people sat down for a living. Today three quarters of us work sitting in offices or drive for a living.

What do we really know about sustained sitting at work, what is the advice and solutions and what leadership should we be looking for from the health and safety community?

Prolonged sitting – a definition

There’s no single definition of what counts as prolonged sitting, though some studies argue that anything from 30 minutes to 12 hours of unbroken sitting can be bad for health. The HSE’s Displace Screen Equipment (DSE) guidance (for use alongside the 1992 DSE regulations) recommends taking a five to 10-minute break every hour of continuous screen use. This is to give the body as well as the eyes a break – with advice to ‘vary posture’ or focus on distant objects.

Evidence for health risks

There is some recent evidence linking sitting with the risk of death. In 2017, a study of 7,985 adults in America found that participants who spent more of their waking hours sedentary were more likely to die during the four-year follow-up.

The findings, published as Patterns of Sedentary Behavior and Mortality in U.S. Middle-Aged and Older Adults, said that both the total volume of sedentary time and its accrual in prolonged, uninterrupted bouts was associated with all-cause mortality.

Sitting has been linked to specific and serious health outcomes. A large study of 68,497 women also in the US published in 2003 showed that for each two-hour period spent sitting at work, there was a seven per cent increase in diabetes.

Interestingly, the reverse was true in that for each two hours’ of standing or walking about, there was a 12 per cent reduction in diabetes. In women, a standing or walking occupation has been associated with a lower risk of cancer compared to sitting occupations, according to an study by Stamatakis et al in 2013.

The exercise factor

Exercise as a way to beat the effects of prolonged sitting is contested. A study on sedentary behaviour done by the University of Sydney, Australia and Loughborough in the UK of 150,000 Australian adults found that premature mortality and cardiovascular disease was an issue in the least physically active groups – those doing under 150 minutes of exercise a week, suggesting that exercise could be enough to offset the risks of sitting.

However, in Patterns of Sedentary Behavior (cited above) scientists found that regardless of body mass index or exercise habits, the risk of death grew in tandem with total sitting time and sitting stretch durations in excess of 30 minutes. “If you have a job or lifestyle where you have to sit for prolonged periods, the best suggestion I can make is to take a movement break every half hour,” said lead author Keith Diaz. “Our findings suggest this one behaviour change could reduce your risk of death.”

Standing to work can burn an extra 50 calories per hour compared to sitting. Photograph: VARIDESK

Sitting has been linked to obesity. NHS says prolonged sitting can slow the metabolism, which affects the body’s ability to regulate blood sugar, blood pressure and break down body fat. In Denmark, 4,732 working adults participated in a study (Eriksen et al 2015) which found a positive association between change in occupational sitting time and BMI.

What has this to do with health and safety?

HSE says that there are no specific regulations controlling the risks around sedentary work. However, both the Health and Safety at Work Act 1974 and the Management of Health and Safety at Work Regulations 1999 require employers to protect their employees from risks to their health, which would include sedentary work.

It is HSE’s role to provide leadership and set the agenda for what it expects employers to do in health. In February this year HSE commissioned the Workplace Health Expert Committee (WHEC), which advises it on emerging risks, to provide scientific evidence that could inform its policy around sedentary working.

Sedentary Work and Health, the paper produced by WHEC, is a good summary of research. The paper agrees that ‘systematic reviews’ have demonstrated risk associations for cardiovascular disease, type 2 diabetes, colon, endometrial, lung and breast cancers and depression in people who sit for long periods.

However, WHEC said it was not possible to isolate or prove the health impacts for occupational sitting. WHEC thinks studies have mixed leisure behaviours (such as watching TV) into their results, and the potential for reverse causation (individuals bringing existing health issues into the workplace) is a challenge.

HSE’s conclusion is that more research must be done. Future work could include using wearable technology to obtain valid exposures and to assess the effectiveness of control measures. Future workplace intervention strategies may also seek to prioritise women and young people, who HSE says seem to be at greater risk of adverse health outcomes from sitting.

New guidance

Gavin Bradley, founder of Active Working says however that we know enough already and that guidance must just urgently catch up with the risks faced now: “The DSE regulations were developed over 30 years ago. They were designed to ensure those who sit at their desks do so comfortably. They do not draw sufficient attention to the risks of prolonged or excessive sitting so we need to start again.”

Active Working is a consultancy which works with firms to ‘increase employee wellness and performance through break-up and reduction of workplace sedentary behaviour’. It also runs the On Your Feet Britain campaign which populates advice through social media. With the tags #SitLess and #MoveMore workers are urged to have fun in coming up with creative ways to move, such as having walking meetings or standing for phone calls.

Walking meetings can encourage creative thinking as well as helping to incorporate movement into the day. Photograph: iStock/bernardbodo

Bradley has also helped to draw up new recommendations around healthy sitting durations and breaks. The Expert Statement on the sedentary office, published in British Journal of Sports Medicine 2015, was co-signed by Public Health England and several universities.

It goes much further than the DSE regs, advising desk-based workers to incorporate two hours a day of standing and light activity (light walking) during working hours, eventually progressing to a total accumulation of four hours a day. “To achieve this, seated-based work should be regularly broken up with standing-based work, the use of sit–stand desks, or taking short active standing breaks.”

It has a clear message for employers: “Companies should advise staff that prolonged sitting, aggregated from work and in leisure time, may significantly and independently increase the risk of cardiometabolic diseases and premature mortality.”

Get up, stand up?

Sit–stand (or stand–up) desks appear to be the ideal solution to integrating so much movement and standing into the office environment. Are they any good?

Safety Management has been trialing stand-up desks made by Varidesk. My personal experience has been amazing, it has got rid of the worrying lower back twinges I experienced after extended sitting, and I would not swap the freedom of movement the flexible desk gives for sitting all day for anything (you can read my review online: https://bit.ly/2XM3TLo).

But what do the health experts say about standing desks as the solution to our chair addictions?

Professor Karen Walker-Bone is director at Arthritis Research UK/MRC centre for Musculoskeletal Health and Work. Her view was surprising. She said although studies show that prolonged sitting puts pressures on the discs in the back, pressure levels have not been shown to be any higher compared to prolonged standing.

Further, she said that although there have been some studies linking positive health outcomes to standing desks, they aren’t reliable. “There’s not enough high quality evidence to say there’s a difference for back pain,” she says, qualifying: “That’s largely because the studies have [involved] people who are not necessarily different from an average worker, they haven’t said that having back pain is a problem.”

Walker-Bone did say that my improved back health could be down to the opportunity standing desks provide for lifting legs, shifting weight or posture. “By standing, you ameliorate that because you probably don’t stand completely still for very long, you probably shift from one foot to the other a bit more.”

 “Standing allows for more movement than if you are sitting for four hours at your computer when you really don’t move at all, you get focused on one thing. For me the danger is the static posture, whichever one.”

The stand–up desk I trialled allowed for more movement than when sitting

The need for intervention

How much help do employees need in this area? Often, advice for computer users around posture and breaks is a ‘tick’box’ exercise, perhaps done on induction and then swiftly forgotten.

At Lambeth Council, however, leaving employees to their own devices has brought health problems, says its HR and organisational development director, Dean Shoesmith. “Since moving to our new buildings just over a year ago, we’ve seen an increase in musculoskeletal conditions, which is the council’s primary reason for absence, ahead of stress-related conditions,” he explains.

A new ‘hot-desk’, set up in Lambeth Council’s modern accommodation, has meant employees moving regularly to different desks and unfamiliar set-ups. “Equipment is flexible with fully adjustable chairs and PCs on movable arms, but staff often forget to make the adjustments they need to work comfortably,” he says. The Council is tackling the issue proactively. “Like all culture change, this takes time and constant reinforcement and education of adopting good posture and taking regular breaks.”

Research into this topic has uncovered a body of evidence that says that prolonged sitting carries some pretty big health warnings. Although HSE says there aren’t enough studies that can pinpoint these to the workplace, largely it’s about common sense. It feels good to vary movement in the day, it does not feel great to sit for ages.

Whether you invest in a stand-up desk, or make a commitment to use the stairs whenever you can, the answer is quite simple. “Our bodies were made to move, ” says Walker-Bone. “What we should be doing more really is moving our bodies.”

HSE Sedentary work & health: https://bit.ly/30wfSht

Chair exercises for wellbeing - a video from British Safety Council here




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