Can Physical Activity Offset Sitting-Associated Health Risks?

In March (here), we reported on an economic impact study of the National Health Service (NHS), which identified the extent to which physical inactivity is associated with adverse health outcomes, such as cancer and cardiovascular disease (CVD). Indeed, it was calculated that in 2016/17, 70,000 deaths could have been avoided, but for sedentary behaviour. This led some experts, quoted in a Daily Mail article, to characterise sitting as ‘the new smoking’.[i]

Having reviewed the accuracy of the Daily Mail’s reporting, the NHS remarked: 

‘Though it is likely that prolonged inactivity is bad for our health, we do not know from this study how much physical activity we need to offset the hours we spend sitting. A few extra minutes, or even an hour, spent standing is unlikely to have the same benefits as regular physical exercise’.[ii]

Earlier this week, in the Journal of the American College of Cardiology,[iii] new study findings revealed that 150 minutes of moderate exercise per week, or alternatively, 75 minutes of vigorous exercise per week, can eliminate the association between sedentary behaviour and all-cause mortality risk.[iv]

The purpose behind the University of Sydney’s research was to consider the mortality risks associated with a lack of physical activity and excessive sitting. Further, it sought to measure the advantages and disadvantages of replacing sitting with standing, physical activity and sleep.

Around 150,000 Australian men and women, over 45-years-old, participated in the study.

They were instructed to complete a questionnaire, which asked how much time they spent sitting, standing, sleeping (per day) and walking or participating in moderate or vigorous physical activity (per week).

After 8.9 years and 7.4 years, respectively, the researchers followed up on the study participants by assessing all-cause and CVD mortality.

Higher mortality risks (all-cause and CVD) were most commonly observed in those who sat for more than 6 hours per day and did not satisfy the recommended Australian physical activity level (150-299 minutes per week).

Those who met the lowest requirement for physical activity, i.e. 150 minutes per week, were able to eliminate the association with all-cause mortality risk, unless they sat for more than 8 hours per day.

The risk remained substantially elevated in those who were active for 1-149 minutes, but sat for just 4 hours per day.

‘In the absence of some physical activity, merely reducing sitting times may be insufficient for better health’, said lead study author and Professor of Physical Activity, Lifestyle and Population Health, Emmanuel Stamatakis, PhD

What is more, given that standing also yielded an insufficient reduction in risk, he advised that:

‘... substituting sitting for brisk walking may be a better option that is feasible by a majority of adults’.

In the Health and Safety Executive’s (HSE) Seating at Work Guide, it emphasises the importance of employees being allowed to move around after sitting or standing for long periods. Is it only a matter of time until the HSE proposes that employers should be encouraging more regular and more strenuous activity during breaks from seated and standing positions?

5.png

 

[i] Lucy Elkins, ‘Is sitting REALLY the new smoking? Alarming new research claims 70,000 deaths a year are caused by our increasingly sedentary lives - that's even more than lung cancer’ (25 March 2019 Daily Mailhttps://www.dailymail.co.uk/news/article-6849397/Alarming-new-research-claims-70-000-deaths-year-caused-increasingly-sedentary-lives.html> accessed 27 March 2019.

[ii] ‘Does prolonged sitting really kill 70,000 people a year in the UK?’ (26 March 2019 NHS) <https://www.nhs.uk/news/lifestyle-and-exercise/does-prolonged-sitting-really-kill-70000-people-year-uk/> accessed 29 March 2019.

[iii] Emmanuel Stamatakis et al, Sitting Time, Physical Activity, and Risk of Mortality in Adults Journal of the American College of Cardiology Apr 2019, 73 (16) 2062-2072; DOI: 10.1016/j.jacc.2019.02.031 <http://www.onlinejacc.org/content/73/16/2062> accessed 25 April 2019.

[iv] Mary Kekatos, ‘You can cancel out harmful effects of sitting down all day if you walk home instead, new study suggests’ (22 April 2019 Daily Mail) <https://www.dailymail.co.uk/health/article-6947777/You-cancel-harmful-effects-sitting-walk-home-instead-new-study-suggests.html> accessed 25 April 2019.