Aging, sedentary behaviour and the beneficial effect of an active lifestyle

By Guy Hajj-Boutros, M.Sc.

It is a well-recognized fact that our society is growing older. This aging of the population is observed in developed as well as in developing countries, albeit at a faster pace in the latter. According to the World Health Organization, the aging of the population is an unprecedented phenomenon in human history. Although many anticipate this demographic revolution with apprehension, it is in fact a triumph of mankind over the adversities of the environment. Among many societal challenges posed by the aging of the population is a growing prevalence of multiple chronic diseases and functional impairments of older adults, giving rise to the geriatric syndromes, especially in those above 85 years of age. Still, there is evidence that we are aging better. Life expectancy at age 65 has steadily increased in most developed countries to reach current levels of about 85 years for women and 80 years for men. Thus, even at age 65, there is opportunity to introduce preventive medicine and to educate people to adopt healthy and active lifestyles and prevent many of the deleterious effect of aging.  

Aging is a heterogeneous phenomenon that is the result of the interaction between the individual genetic background and environmental factors, not the least of which is the adoption of a healthy lifestyle. For example, onset of type 2 diabetes can be delayed or prevented by in regular physical activity and healthy eating habits. There are also several social and psychological determinants of health, including education, income, social status, social participation, perceived control over one’s life, positive attitude, to name but a few.

In future discussion, we will present several aspects of healthy aging that are at reach to many older adults for a healthy and fulfilling life, namely physical activity, dietary habits and social participation. But first, it is important to understand the consequences of the sedentary behaviour and why active lifestyle might be a solution for a better aging.

Current guidelines for physical activity in older adults by the American College of Sports Medicine and the American Heart Association recommend performing a minimum of 30 min of moderate intensity endurance physical activity 5 days per week or 20 min of vigorous intensity endurance physical activity 3 days per week. In fact, these recommended guidelines may be difficult to achieve for most individuals and that only 12% of the elderly population (60 to 79 years old) in Canada meet these physical activity guidelines. In older individuals, there is evidence to suggest that the majority of their time is spent in a sedentary state (e.g. sitting) during the waking day. Several studies have examined if long periods of sedentary behavior such as sitting may be associated with any negative health outcomes. For example, a recent meta-analysis showed that prolonged sedentary behavior was associated with an increased risk of all-cause mortality, cardiovascular diseases, type 2 diabetes and cancer. In addition, high sitting time has been reported to increase cardiovascular disease mortality by 2.7 fold compared to low sitters in an elderly population. Moreover, a meta-analysis showed that higher amount of sedentary behavior such as sitting was associated with an increased risk of metabolic complications by 73%. There is even evidence to suggest that obese individuals sit 2 hours longer compared to lean subjects. Interestingly, this study noted that the energy expenditure of obese individuals could increase by 350 kcal per day if they applied the postural behaviors of lean subjects. Therefore, one could argue that sedentary behavior could decrease cumulative energy expenditure due to the loss of a large amount of muscle contractions that could occur throughout the waking day. This quantity of energy expenditure has been coined as non-exercise activity. Evidence has shown that the energy expenditure from non-exercise activity is higher than structured exercise such as walking for 30 min a day 5 times per week or running 35 miles a week. Thus, health professionals should not neglect this type of energy expenditure.

It should be noted that sedentary behavior for prolonged periods in physical active individuals has been described. For example, there is evidence to suggest that high sedentary time may be associated with chronic diseases independent from overall physical activity. Thus, sedentary behavior appears to be an important predictor of health outcomes that goes beyond the level of physical activity of an individual. However, in a recent meta-analysis that included more than 1 million subjects with a follow-up of 2-18 years, showed that 60-75 min of moderate physical activity per week seems to eliminate the increase risk of mortality associated with high sitting time (>8 hours per day). The authors also showed the same physical activity level attenuated but not eliminated the risk of mortality associated with high TV watching (>5 hours per day). A potential method that could counteract the negative health effects of prolonged sedentary behavior would be to increase the number of break up times. Accordingly, breaking up sedentary time appears to have positive effects on multiple metabolic risk factors. Therefore, the idea of specifically decreasing the amount of sitting time in future physical activity guidelines should be considered. However, an important question that remains unresolved is whether standing for long periods throughout the day is sufficient to eliminate the risk of disease. Health professionals could encourage different option/activities to older adults that may limit sitting time such as stand-up desks for computers, interactive videos games, standing when using public transportation, devices that vibrate when sitting too long and the use of stairs.

Collectively, based on the above evidence, decreasing sedentary habits is associated with additional benefits by reducing several cardiovascular diseases and all-cause mortality without major lifestyle changes. Older adults may consider reducing their sitting time and implementing more active breaks for a better aging.

References

1. Statistics Canada. (2015). Directly measured physical activity of Canadian adults, 2012 to 2013. Health Fact Sheet. Statistics Canada Catalogue no. 82-625.
2. World Health Organization (2015). World report on ageing and health. Geneva, Switzerland.
3. Nelson, M. E., Rejeski, W. J., Blair, S. N., Duncan, P. W., Judge, J. O., King, A. C., Castaneda-Sceppa, C. (2007). Physical activity and public health in older adults: recommendation from the American College of Sports Medicine and the American Heart Association. Medicine & Science in Sports & Exercise, 39(8), 1435-1445.
4. B.H. Hansen, E. Kolle, S.M. Dyrstad, I. Holme, S.A. Anderssen, Accelerometer-determined physical activity in adults and older people, Med Sci Sports Exerc 44 (2012) 266-72.
5. Biswas, P.I. Oh, G.E. Faulkner, R.R. Bajaj, M.A. Silver, M.S. Mitchell, D.A. Alter, Sedentary time and its association with risk for disease incidence, mortality, and hospitalization in adults: a systematic review and meta-analysis, Ann Intern Med 162 (2015) 123-32.
6. T.M. Manini, J.E. Everhart, K.V. Patel, D.A. Schoeller, L.H. Colbert, M. Visser, F. Tylavsky, D.C. Bauer, B.H. Goodpaster, T.B. Harris, Daily activity energy expenditure and mortality among older adults, JAMA 296 (2006) 171-9.
7. C.L. Edwardson, T. Gorely, M.J. Davies, L.J. Gray, K. Khunti, E.G. Wilmot, T. Yates, S.J. Biddle, Association of sedentary behaviour with metabolic syndrome: a meta-analysis, PLoS One 7 (2012) e34916.
8. J.A. Levine, L.M. Lanningham-Foster, S.K. McCrady, A.C. Krizan, L.R. Olson, P.H. Kane, M.D. Jensen, M.M. Clark, Interindividual variation in posture allocation: possible role in human obesity, Science 307 (2005) 584-6.
9. M.T. Hamilton, D.G. Hamilton, T.W. Zderic, Role of low energy expenditure and sitting in obesity, metabolic syndrome, type 2 diabetes, and cardiovascular disease, Diabetes 56 (2007) 2655-67.
10. U. Ekelund, J. Steene-Johannessen, W.J. Brown, M.W. Fagerland, N. Owen, K.E. Powell, A. Bauman, I.M. Lee, C. Lancet Physical Activity Series 2 Executive, G. Lancet Sedentary Behaviour Working, Does physical activity attenuate, or even eliminate, the detrimental association of sitting time with mortality? A harmonised meta-analysis of data from more than 1 million men and women, Lancet 388 (2016) 1302-10.
11. F.B. Benatti  M. Ried-Larsen, The Effects of Breaking up Prolonged Sitting Time: A Review of Experimental Studies, Med Sci Sports Exerc 47 (2015) 2053-61.