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Who is at risk of too much sitting in construction?

Dr Nick Gilson

Presented by: Dr Nick Gilson, Senior Lecturer at the School of Human Movement and Nutrition Science.

Run time: 31:01

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Construction Work Health Forum Podcast

Presented by: Dr Nick Gilson


Dr Nick Gilson:

Thank you very much. I've never had an introduction like that ever before. I don't have any balloon tricks, I promise.

I'm here to talk to you about sedentary work. I'm going to talk to you about this important topic from a chronic disease and illness perspective. So that's important to kind of set out my stall there. Rather than a health and safety at work, it's a health and wellbeing at work issue. What I'm going to do in my presentation, about 40 minutes, is pull on an evidence base which has really exploded over the last ten years. You can see there in that top graph in my area of publications, in public health and population health and wellbeing, there's been a five fold increase in the amount of studies which have dealt with sedentary behaviour in the occupational environment. That's compared to really a kind of steady flow on for health and safety publications.

So using that evidence, I'm going to talk about four key areas. The first is I want to just define what sedentary behaviour is for you. That's different from inactivity. That's very important to be aware of. Next, I'm going to talk about exposure; what we know about how much people are sitting, both in the workplace and outside of the workplace. Then I'm going to talk a little bit about impact. Which is very important from a health perspective, but also from a productivity perspective. Then finally, I'm going to talk about some of the things that we've been doing around intervention and trying to get people to sit less, stand more and move more at work. All of that is wrapped up in this kind of context of construction, which is a very interesting area. I'm going to try and contextualise that for you and post three key take away messages as I go through the presentation. Okay?

So first of all, what is sedentary behaviour? Well a good way of getting a handle on it is to look at the concept from an energy expenditure perspective. Okay? This is a continuum which moves from sedentary to very vigorous activity. We measure this continuum on a unit of energy exchange called the met. So you guys, at the moment, you're expending one metabolic equivalent at the moment, just over, because you're sitting still, just about. If you would get up and move incidentally, you'd move into that light area. Then if you were to brisk walk, then you'd be into moderate intensity physical activity. Which a threshold relative to mets is about three, four that. Okay? So it's useful to think about sedentary behaviour on that scale. This is our defining definition that we have in the area. Which not only takes in mets – so 1.5 mets or below is sedentary behaviour. But also a postural aspect. Okay? So it's about sitting and low energy expenditure during waking hours. That's quite important.

Okay, now sedentary behaviour, very quickly, is very different from inactivity. What we do a lot of is we go out into the field and we use devices called accelerometers. These are little monitoring devices you can clip onto your belt or you can put onto your wrist. They measure energy exchange. We can get a very, very detailed and accurate measure of sedentary behaviour and physical activity through those monitors. These are two classic graphs from an accelerometer. The first one at the top there shows that big spike where the individual or participant is getting 30 minutes of moderate to vigorous physical activity in the day. Do you know what the guidelines are for physical activity? [Long pause] no? You've got to accumulate a minimum of 150 minutes of moderate to vigorous physical activity through the week. So that's about five blocks of 30 minutes. That individual, on this day, is getting their 30 minute dose. But what do you notice about the rest of the day? [Long pause] highly sedentary. So this person is both active but also highly sedentary through the day.

Now what do you notice about the bottom graph? No big spike. This individual is actually inactive relative to the guidelines, but is less sedentary than the participant above because they're getting their little spikes through the day. So it's important to be aware of the distinction between sedentary behaviour, which is really sitting a lot, and inactivity, which is not meeting the guidelines.

Okay, so moving on. How much sedentary behaviour do we do in a typical day? Have a guesstimate for yourselves. How sedentary do you think you are? [Long pause] about six hours? Anybody more than that? Hands up. [Long pause] anybody less than that? [Long pause] okay. Well what we do is we map exposure through the day. This is your typical kind of routine if you've got an office based job. So you wake up. You're into breakfast. You're sitting in transport. You're sitting usually in your work for many hours. You're sitting in transport back. Then if you're lucky, you get time for that 30 minutes. Okay? So really, sedentary behaviour and exposure is ubiquitous in our modern day society.

It's not always been like that. If we think about the main driver for high sedentary behaviour, it's the occupational context. Your typical person sits for about eight to ten hours a day, with half to three-quarters of that in occupations. You can see that nice kind of time analysis there in the two graphs showing that from the 1960s up to the present day, we've got more and more sedentary. The main driver for that is sedentary occupations. Okay? Which as important point to recognise.

Now office work is much more prevalent in society today. We've also got non-office based work where we've got increased mechanisation and technology which is promoting sitting. But if you look at total occupation energy exposure, that's dangerous for health. But it's also the pattern of exposure. So what we've done with this little device here – it's a pressure pad. We've put this on lots and lots of chairs in offices and we've got a pattern emerging of the type of sitting that people do. These blocks here – the black blocks – it's Monday, Tuesday, Wednesday, Thursday; one participant. The black blocks are sitting. The white blocks are not sitting. You can see the variation between the days. So on Monday, the first bar, there's lots of prolonged sitting there. Okay? In the third bar, on Wednesday, there's lots of breaking going on there. So prolonged sitting and breaking sitting is also very important for health. It's not your total exposure; it's your pattern of sitting that you need to be aware of.

Now what about construction? How much sedentary exposure happens in your industry? Well, this is the only piece of research that I've come across from Safe Work Australia which looks at sedentary exposure in the construction industry. You can see there the difference between men and women and how it ranks up against other industries like manufacturing. So for male construction workers; that data is suggesting that they have the lowest sedentary exposure out of those industries. But look at the difference with women in the industry as well. But even with men, you're still looking at a 60% exposure rate, which is still very high. But the important thing to be aware of with this measurement is that it's self report and it's a very loose indicator. So we don't have any incredibly detailed data on how much people sit in the industry in their different occupations.

Now I've gone to the literature and pulled out some of the key studies. I only came across three studies which looked at construction workers. This one was from Danish workers. You can see there construction workers, mobile plant operators, 3.5 to 4.5 hours a day. That is measured with accelerometers, so it's a good measure. But a low sample size. We want big sample sizes to get a good indicator.

This one is unpublished data from a group that I work with in the Netherlands. Forty-four per cent of the day, male construction workers spent sitting. Now this is an important piece of data, I think, for the construction industry. Now there's lots of jobs there that are very vigorous in your industry, I'm sure. But the flow on effect then for other domains of sitting in leisure and transport is also high. So in vigorous occupations, this very large dataset is suggesting that construction workers may sit the most in other domains outside of work. So it's important that we target those other domains as well.

I suppose my first question – really, we know very little about sedentary exposure in construction work. That's going to be my first take away message. This is a model we use a lot in my area where we try and build from relationships between disease to translation; where we're trying to change population incidents and we're trying to change policy. At the moment, in non-office based work, we desperately need some measurement based studies to develop a good evidence base so then we can target the appropriate sub-occupations in the construction industry. Develop some tailored interventions, test them. Look at what's good, what's bad and then begin to translate, if we can.

So if we do think about exposure, where might prolonged sitting least occur? Would you agree with that? This is my general thoughts and ideas. So supervisors, manual skilled labouring on site and then you've got your tradies; electricians, carpenters, plumbers, etcetera. Where sitting might most occur is in these areas; so power crane operators, mobile crane operators, machine operators and, of course, I'm guessing there's increasing desk work in the construction industry. Would I be right in suggesting that? Okay. So that's also a big area of concern.

Okay, I'm going to move on to impact. Okay? Who's heard of this term chair disease? [Long pause] ever heard of that? Anybody seen anything in the media over the last six months? You're nodding your head. What did you see?

Okay. So the general gist is if you sit a lot, you're going to die earlier. Is that right? Almost worse than smoking. Now there was a great 60 Minutes report – and I'm happy to send you these slides so you can have a look at that – which outlines the danger of sedentary exposure. You've got that reference to sitting, which I don't think is particularly helpful. Because there's a linear relationship between smoking and cancer risk. So you've got zero tolerance for smoking. Now with sitting – sitting is healthy. We all do it. It's nice. It's relaxing. We don't want to take sitting out of the day completely. It's important to sit. But what we do is we too much sitting. That's the problem. So we've got to transition between sitting, standing and moving more. So that headline there about the new smoking is, I don't think, particularly helpful.

Then you've got some things which have filtered in through the epidemiology literature which shows increased risk. Then you've got these things here, which have most recently occurred. This is a newspaper I picked up from the train. When I was standing, of course, not sitting. You can see there the complete opposite message. Sitting does not shorten your life. Okay? Then this appeared in The Australian. Sitting is okay as long as you keep moving. So it's all really confusing. If you look at the epidemiology literature sometimes, to use a construction analogy; it's a bit like a pile of bricks. Okay? We're trying to construct something and it doesn't make much sense.

But I guess, as a scientist, what we are doing – and if you'll excuse the pun, we are trying to construct a solid argument for the importance of reducing prolonged sitting. Okay? This remains, for me, one of the most powerful messages. From a great Canadian study on over 17,000 people – and this is total sitting across the day. Now your risk of mortality is about 15% higher if you sit all the time. Okay? That's a very, very powerful message.

Now very quickly, because I want to move on to the area of intervention and productivity. What is the physiological basis for why prolonged sitting is a risk? Those are the key things that we've lined it to; premature mortality, cardio metabolic markers and also some cancers, specifically breast cancer for women and colon cancer. Now the physiological foundation for standing and moving more and not sitting a long time can really be broken up in to three areas based around muscle contraction. Okay?

This is an EMG trace. It's basically measuring the muscle activity when you sit, when you stand and when you walk. Logically, of course, you've got hardly any activity when you're sitting. You've got some small contractions when you're holding posture when you're standing. You've got bigger contractions when you're moving. Okay? Now if you want to look at the benefits of standing and moving, they can be linked to metabolic regulation. Okay? So basically, a key enzyme in your muscle, when you stand, when you hold a posture, when you move; you release this enzyme, lipoxygenase, which regulates glucose and lipid metabolism. Okay?

You also use energy. So you're not converting that energy to stored fat. You're using it up and you're accumulating it through the day. The new area of science is around gravitational resistance. Which is coming through now from space science which suggest that when you stand, your body tries to distribute your blood – your mean arterial blood pressure – through the body because it doesn't want to pool in the legs. So there are very small things going on in your body which regulates that mean arterial blood pressure. Which is also proving to be quite important. Okay? So health wise and chronic disease wise, those are the three areas that are important.

But what I just want to introduce you to quickly to, which I think is equally important for business, is this carrot and stick argument around not just making or kind of trying to produce a healthy environment for workers, but also trying to produce a business model around productivity for business.

Now if we think about the stick model, we've got an issue of duty of care there. I'm not going to go there. But it's important to recognise that we've recently had out in the public domain now a case which has been brought to ComCare around sedentary exposure risk and ill health. It got knocked back on appeal as well. But we're going to see more of these cases coming through. So there's an issue of duty of care and accountability there for business. But equally from a carrot perspective, we've also got issues around productivity and illness and absenteeism. Which costs the Australian economy billions per year. Okay? So if we can target the type of behaviours which are contributing to our workers' sickness, we're going to benefit health and, therefore, the productivity of industry.

But along with absenteeism, we need to recognise this concept of presenteeism. Have you come across that term before? I'm sure you have in your area. You're at work but you're not focussed. You're not dealing with the tasks that you need to do. The cost of presenteeism, in that context, is even higher than absenteeism. So what I'd like to put forward to you – and again, this is a hypothesis – is prolonged sitting exposure linked to presenteeism issues.

Now if we look at the evidence – there's a few studies. They're cross-sectional. So they're not randomised and controlled. We haven't got good quality evidence there. We're using self report measures, which are not great indicators of productivity. The studies we've done – the people we recruit into those studies tend to be really productive and happy anyway. Okay? So we have an issue with variability there. So the evidence is tenuous. But what we've got is we've got these studies coming through – through lab based studies which are trying to explore the link between sitting, standing, moving and presenteeism in the workplace.

Now these are standing desks. Does anybody have a standing desk at work? And you use it? Okay. We're testing these standing desks at the moment with one of these. Anybody got these at work? [Long pause – Laughter] you want one? Okay. These are treadmill desks. Now we're not proposing that everybody goes out and gets a treadmill desk. I can't really see these working in power cranes or mobile cranes or those types of things.

[Laughter] what we're doing is we're using these different ergometers to control sitting, standing and moving in an experimental study. So what we do is we're recruiting people into the study, they go through these different conditions. What we do is, at the end of the day, we measure EEG. Which is basically brain function in the frontal area of the brain here. Now those areas of the brain are all associated with executive function. So that means focussing on tasks. Okay?

Our hypothesis was if we energise the workplace and we get more standing and moving, can we get better executive function? This is hot off the press. We haven't published this yet. But this is some preliminary data. It's suggesting that yes, we do. Now the three bars there are the different conditions. So we've got sitting, standing, moving. The height of the bar represents your cognitive resource. So the higher the bar, the better you're able to focus. Okay? The positive area is all about focussing on the things that you need to do and should do and are urgent. The negative area is all about the stuff that you can put to the side and is not urgent and you can put away for another day. The neutral side is the stuff that you don't need to pay any attention to whatsoever. You can see, from that EEG trace, that you get better response if you get movement in the day. Which is quite exciting. It's all experimental. We're yet to take that out in the field.

So if you think about it – if you've got cognitive resource and you're energising the work environment – you're not spending hours and hours sitting. You're going to get better attention on urgent tasks. You're going to delegate non-urgent tasks. You're going to avoid inhibitory tasks. That's what our data is suggesting. Okay? Now if you can translate that to other occupational groups in the construction industry which are very important for operation, that's going to be quite powerful.

Okay, so ten minutes left. This is my take away number two. Minimising the risk of prolonged occupational sitting is important. You're aware, many of you, of the stuff that's filtering through into the media around chair disease. But also, we've got a developing area for work performance productivity and presenteeism which is going to be very important in the next five years.

Okay, so we'll move onto my last four areas and think about intervention models. Do we have any guidelines for sedentary exposure? [Long pause] do you guys have anything from a health and safety perspective? [Long pause] I don't know.

Yep, okay. From a chronic disease perspective, we don't have any guidelines yet. We're still developing them. The epi evidence just isn't there yet to go and hang your hat and say this is exactly the amount of sedentary exposure you should have in the day. Some groups have attempted to do that. Okay? So for total sitting, a very good group in Sydney have pushed out a huge study which is suggesting an increased risk of 5% for every hour over seven hours. So that might be a threshold, seven hours. There's been some colleagues for desk based jobs which have suggested that we interrupt sitting every 20 to 30 minutes for two to five minutes. Okay? Then we can go back to sit again. That's all about the patterns. Most recently, a group from the UK have tried to apply it to the workplace and suggested that we must try and accumulate two hours, increasing to an ideal of four hours of standing and light intensity activity.

Now is that doable for your industry? That's the question. That's the key question, the golden question. Okay?

If we translate that to different industries, we might have different bespoke models that fit different tasks, jobs and industries. The first one at the top there might be the minimal model where at least we're trying to get some walking in at lunchtime and some movement. The one at the bottom might be the ideal model where we're cycling through sitting, standing and moving very regularly in the occupational space. Other industries and jobs might fall in between.

So I think, at this point in time, it's important to realise that we haven't got one message that will fit everybody. What we need is research, good quality studies which can trace exposure and fit models to occupational groups. When we do that and we intervene – and if we're going to intervene successfully – so not just when my team walks into a workplace for 12 weeks and tries to change things. But for sustainable change, we need to hit not just the individual and the environment, but also the organisation and the policy of that organisation. So it becomes embedded – change becomes embedded.

Now I'm going to finish off with a study that we did which has resonance, I think, for the construction industry. Part of this study revolved around sedentary exposure. We did this study with truck drivers supported by Queensland Government. What we're trying to do is we're trying to change – small changes in eating habits, movement and sitting in truck drivers during the day. Okay?

What we did is we went out – we recruited both long distance and short delivery drivers from the Brisbane metropolitan area. We tried to move their behaviours – both eating, physical activity and sitting – through these wonderfully titled trucks. Okay? Called gear shifts, basically. So what they did is they went out, did lots of environmental mapping for their behaviours and then they tried to gradually and incrementally change that behaviour and build up points to achieve gear shift six over five to six months.

The way that we did that is through this little gizmo here. Anybody got a Fitbit or a Jawbone that you use? Okay, so many of you would be aware of this app. We trained them up in use of the app. We gave them the education, the information they needed. We helped them map their environment; so where change could be focussed. Then they went away and self monitored their behaviours. Sitting and sedentary exposure was very important in this.

Now I'm going to skip through these slides very quickly to get to the results. But this was the intervention plan. So recruitment – we did lots of good baseline measures. We then held workshops. We got them out into their environments, looked at where we could target change. We then did the intervention and we did some follow up measures. For this particular presentation here, I'm just going to show you our data for end intervention and follow up. So basically, did the truck drivers change?

This was our group. Forty-four; it's a pilot study. Heavily weighted to local delivery drivers. We found it really difficult to recruit long haul drivers. They were all men. Worked very hard, long shifts. Multiple shifts during the week. They had very high chronic disease indicators. Okay? High body mass, high waist circumference, high blood pressure, many were on medication. Okay? So a really at risk group.

Basically, this is our case analysis results. Any drivers above the horizontal line changed. Okay? Any drivers below didn't change or even got worse. You can see there, on the left hand side, a lot of drivers actually changed their behaviours during work to increase movement and reduce sitting. A number of them didn't. There was a lot of barriers there. Those dots on the right hand side pretty much reflect long distance driving. Okay? So a very, very tough group to change. We learnt a hell of a lot from that particular study.

But we did lots of interviews as well. I've just pulled out a few for there in my closing comments. That was from one driver about the use of the smartphone app and the activity tracker band. So it was targeting simple stuff. It wasn't asking them to go to the gym or go swimming. It was just, you know, enjoying your breaks. Can you get up? Can you move? Can you accumulate movement and steps rather than sitting? Okay? Can you park the car further away; build up that energy exchange? We got some great feedback from the app. Okay? It's a great data collection tool. So we were in touch with the drivers constantly. We were able to provide guidance across the five months, provide motivation. So for example, this driver here – the smartphone gave feedback and encouragement. You can see that bit there about one of the movement spikes. [Long pause] just moving on the spot while the load is taken off the truck. Diet stuff. Simple messages. Sleep and quality of sleep; a major issue for drivers. Okay? Really beneficial for sleep quality because the band also measures your quality of sleep.

This is the piece de resistance, what my career is heading towards. It actually shows that getting lost in Ikea can actually be beneficial for your health.

Okay, so my final message is can we change sedentary exposure in hard to reach groups? Many of the groups that you work with in the construction industry will be hard to reach. My view is yes. If we take a participatory approach where we engage employees, stakeholders, decision-makers and companies, we can develop programs which can reflect the day to day routines of different types of workers. We can reduce sedentary exposure and make a difference.

With that, I'd just like to thank you. We are continually interested in making connections around research in industry to try and look at this issue. So if anybody would like to meet and chat more, even over lunch or at another point about how we can contribute to making a change in behaviour of workers, then those are my details there. I hope you found that interesting and thank you very much.

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