Introduction

Neville Owen gave an excellent 1st Keynote on Friday’s programme at WCAA 2012.  He presented “New Insights into Sedentary Behaviour and Older Adults” and I also caught great presentations from the following: Charles Matthews, Emmanuel Stamatakis, Margaret Grant, Benedicte Deforche, Paul Gardiner, John Buckley, Yu Ling Chen, Shilpa Dogra, Iuliana Hartescu, Sally Barber, Sandra Agyapong-Badu, Susan Pivavet, Ceilia Edwen, Sandra Van Oostrom, Ruth Melo, Carla Nascimento, Karen Francis, Jitka Jancova, Jaime Cuenca and many others report the importance of sedentary behaviour within their presentations.  So here’s a wee summary of the lay of the land in sedentary behaviour (SB) territories over a 3 part series.

 “Sedentary behaviour is any waking activity characterised by energy expenditure of ≤ 1.5MET’s and a sitting or reclined posture” (SBRN, 2012)

 With the emergence of the digital revolution we have the opportunity to sit in most environments, domestic, work, travel and leisure.  The problem with large amounts of sitting, is that we tend not to use very much energy (usually less than 1.5METs), obviously there are a quite a few exceptions propelling a wheelchair, cycling, horse riding, rowing, seated manual work, and so on.  The notion of sitting being detrimental to health is not a new one and research goes back to Morris, et al., work in 1953 where he observed the incidence coronary heart disease to be higher in bus drivers and telephonist, than in conductors and postal workers (respectively). From there, the message was to increase physical activity and we now have national guidelines on physical activity for all age groups.  So now we are beginning to shine the spotlight on sedentary behaviour.

Neville Owen presented the keynote with information from a population level right down to a cellular level; demonstrating that there is a detrimental health association with being sedentary, relating to morbidity (cardio-vascular risk, cancer, metabolic syndrome, diabetes, obesity) and mortality. The strongest associations of which seems to be with TV viewing, we consider TV viewing to be a proxy for sedentariness.  Total sitting time and total sedentary time can also be measured by objective and subjective means.  The patterns and bouts of which seem to be important factor and it may be that even short breaks in SB could perhaps lessen some of the detrimental effects of sedentariness.

Iuliana Hartescu brought to our attention that amount of sleep can also be related to CVD and suggest that maybe sleep should be considered as part of SB, or at the very least consider it alongside SB to observe it bearing.

Some feel that sedentariness is an inevitable part of ageing and indeed with older adults sitting is not always bad, as with all ages, we do need a certain amount of rest and recovery!   There are many social and cultural experiences that shape our behaviour.  As we get older, I guess there has been more time for these behaviours to be cemented in everyday life and perhaps a harder habit to break.  Neville Owen suggest that on average, older adults seem to spend about 60% of their day in SB and the most popular behaviour TV watching, but what we really need to sus out is why this is: is it boredom? Rest? An Information Source? Entertainment?  Jaime Cuenca showed us that older adults actually give very little value to TV watching and give much more value to activities for activities such as hobbies and interaction with the family.

The future:

  • We need further information on causality of the link between SB and negative health outcomes.
  • We need to define minimum dose of sedentariness that we can get away with (freq & duration)!
  • We also need stronger experimental evidence of the biological mechanisms of SB, as it seems to have its very own metabolic consequence separate to inactivity.
  • We need the formation of clear evidence based guidelines on reduction of SB

SB Ref – SBRN (2012) Standardised use of the term “sedentary” and “sedentary behaviour”, Applied Physiology, Nutrition and Metabolism, 37:540-542.

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