Time Spent Sitting & Formal Exercise vs General Physical Activity

In the late 1950s Morris and Crawford (1958) published the results of a study that had discovered that heart disease was more common among bus drivers than bus conductors, and among clerical workers than postmen.

This lead Morris and Crawford (1958, p.2) to the hypothesis that “men in physically active jobs have a lower incidence of coronary heart disease in middle-age than men in physically inactive jobs.”

In the following decades, the associations between occupational activity and cardiovascular disease were confirmed, as were its relations with physical activity generally (Thompson et al., 2003).

However, an additional nuance has recently emerged. Overall time spent sitting has been shown to be associated with cardiovascular and metabolic diseases, as well as total mortality (Van der Ploeg et al., 2012). This relation exists independently of exercise levels. In other words, regardless of time spent in formal exercise, spending prolonged periods sitting can contribute to premature morbidity and mortality.

Although researchers are attempting to further understand and define this relation, the evidence so far has been sufficiently persuasive. One target people should aim for is to reduce time spent sitting at work. Interventions could include:

  • Personally tailored activity;
  • Counselling for employees;
  • Sending motivational email messages;
  • Encouraging the use of pedometers; and
  • Suggesting local walking routes.

However, a recent systematic review concluded that the evidence base for these interventions remains small and more research is needed (Chau et al., 2010).

References

Morris, J.N. & Crawford, M.D. (1958) Coronary Heart Disease and Physical Activity of Work. British Medical Journal. 2, pp.1485-1496.

Thompson, P.D., Buchner, D., Pina, I.L., Balady, G.J., Williams, M.A., Marcus, B.H., et al. (2003) Exercise and Physical Activity in the Prevention and Treatment of Atherosclerotic Cardiovascular Disease: A Statement from the Council on Clinical Cardiology (Subcommittee on Exercise, Rehabilitation, and Prevention) and the Council on Nutrition, Physical Activity, and Metabolism (Subcommittee on Physical Activity). Circulation. 03(107), pp.3109-3116.

Van der Ploeg, H.P., Chey, T., Korda, R.J., Banks, E. & Bauman, A. (2012) Sitting Time and All-cause Mortality Risk in 222,497 Australian Adults. JAMA Internal Medicine . 172(6), pp.494-500.

Chau, J.Y., van der Ploeg, H.P., van Uffelen, J.G., Wong, J., Riphagen, I., Healy, G.N., et al.  (2010) Are Workplace Interventions to Reduce Sitting Effective? A Systematic Review. Preventive Medicine. 51(5), pp.352-356.

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