Recently, stories abound in the popular press on the health risks associated with too much sitting. News anchors talk up the impact of sitting on premature death, story lines read "Sitting kills" and "Get off that deadly chair," whereas e-news stories and streaming video zip along the information highway informing listeners and viewers on the deadly effects of prolonged sitting. So, is this truly news or is it merely a reinvention of an age-old message?
EARLY OBSERVATIONS
Not so long ago, in 1953, Jeremy Morris and colleagues observed that bus conductors who climbed the stairs of double-deck buses in London as part of their regular workday experienced half the number of myocardial infarction cases when compared with their colleagues driving the bus who spent 90% of their work hours sitting (2). A little while before that, in 1713, Bernardino Ramazzini, the Italian physician widely considered the father of industrial medicine, noted that tailors and cobblers who sat at their work and were therefore called "chair-workers," experience general ill health (6). Note that both these examples of early observations on the ill-health effects of prolonged sitting involve workers. Hence, the connection between the workplace setting and the negative impact of prolonged sitting is not new. However, because of the more recent changes in the work environment brought about by emerging technologies and automation, sedentary and sitting tasks have become a usual circumstance for many employees, and the message is highly relevant today.
THE HEALTH HAZARDS OF TOO MUCH SITTING
Sedentary behaviors include sitting in a variety of settings, for example, television viewing at home, sitting while commuting, and screen time during computer use at work are all examples of behaviors with very low energy expenditure across a variety of settings that may occur throughout the course of a single day. During the course of an entire day, repeated throughout weeks and months, accumulated sitting time may have negative consequences for health. Recent evidence reports associations between television time and poor metabolic health, indicating that overall sitting time is related to increased health risk caused by higher waist circumferences, body mass index, systolic blood pressure, triglycerides, plasma glucose, and fasting insulin, as well as lower high-density lipoprotein. Furthermore, leisure time spent sitting (≥6 hours day−1 vs. <3 hours day−1) was associated with 34% and 17% increased risk of death among women and men, respectively, after 14 years of follow-up in the American Cancer Society's Cancer Prevention Study II (4). When sitting was considered in the context of the level of physical activity (≥6 hours day−1 of sitting and being less physically active), the risk of death increased to a 94% higher likelihood for women and 48% higher likelihood for men, respectively, compared with their less sedentary counterparts. In one study, each 1-hour increment in television viewing time was found to be associated with an 11% and an 18% increased risk for all-cause and cardiovascular disease mortality rates, respectively (3). In a recent study from the Cooper's Institute, cardiovascular mortality outcomes related to sedentary behaviors of men after 21 years of follow-up showed an 82% greater risk of dying among men who reported spending more than 10 hours per week sitting in automobiles compared with men sitting in automobiles less than 4 hours per week (7).
BEING AN ACTIVE COUCH POTATO
Too much sitting may be hazardous to overall health and well-being, but does it apply when guidelines for physical activity are met? The current guidelines for health-enhancing physical activity include the accumulation of 150 minutes per week of moderate-intensity activity, or 75 minutes per week of vigorous intensity activity, or a combination of the two where vigorous activity counts double compared with moderate-intensity activity (5). A 30-minute run three times per week or a daily 25-minute walk will exceed the minimum criteria for meeting the physical activity guidelines for health. However, if this same person sits in front of the computer at work for 8 to 9 hours each day or spends 4 hours per day or more in front of the television, this person might be considered an "active couch potato" and has a higher likelihood for metabolic abnormalities. It is questionable whether the time spent in activity is sufficient to offset the deleterious effects of so much sedentary time. Breaking up sitting time appears to be beneficial for health.
BREAKING UP IS HARD TO DO - OR IS IT?
Healy and colleagues from Australia have presented research indicating a beneficial association between breaks in sedentary time and metabolic biomarkers (1). The difference between sedentary time and nonsedentary time was akin to moving from a sitting to a standing position or from standing still to beginning to walk. The higher the number of "breaks" in sedentary time, the lower the risk associated with waist circumference, body mass index, triglycerides, and 2-hour plasma glucose. In fact, there was a 6-cm difference in waist circumference among those with prolonged sitting behavior compared with those who engaged in frequent "breaks" in sedentary time throughout the day.
Based on a review of the sedentary behavior literature, Patel's team identified research gaps related to interventions studies where sedentary time is broken up or reduced with specific emphasis on the workplace setting (4). However, this does not mean that nothing is known about increasing work breaks or reducing prolonged sitting time in the workplace. In fact, some good examples of introducing physically active work breaks already exist in the literature. Table 1 outlines several examples. However, more research is needed to increase our understanding of what works in reducing the ill effects of prolonged sitting time as the result of planned interventions.
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TABLE 1: Examples of Research on the Introduction of Physically Active Work Breaks
PROLONGED SITTING AND WORKPLACE PRODUCTIVITY
Perhaps even more important of an area for research than the impact of prolonged sitting on health is its deleterious effects on productivity and sick leave, especially when it is considered from an employer's point of view. Obviously, a successful intervention that improves productivity as the central outcome provides immediate rationale for a company to invest in such a resource. From this perspective, a close examination of what is available in the area of occupational health and ergonomics makes good sense. Here, the integration of worker health protection (occupational health and safety) and worksite health promotion is an intuitive fit. An excellent resource to consider is the NIOSH WorkLife program (see http://www.cdc.gov/niosh/worklife/guide.html).
IDEAS FOR BREAKING IT UP AT THE WORKPLACE
When workers are exposed to prolonged sedentary time, a program or intervention that provides opportunity for a break from sitting may benefit the health and productivity of employees. Such breaks would include periodic or more frequent standing up (but not prolonged standing that may have its own health-related issues), stretch breaks, and walking breaks, among others. In many cases, the potential to move from a sitting to a standing position (and vice versa) does not necessarily impede with the work routine. For example, conference calls, data entry, and call center work tasks are all examples of work that may be conducted in either sitting or standing positions. On the other hand, stretch breaks or other activity-specific breaks are likely to affect the flow of work tasks in which an employee is involved. For such breaks to fit in the work routine, adaptations may need to be made. Table 2 presents several ideas from public access resources for interventions that may help prompt or provide support for breaking up the prolonged sitting times among employees.
TABLE 2: Ideas for Reducing Sitting Time among Employees
REDUCTION OF SITTING TIME AS PART OF A LARGER PROGRAM
Comprehensive, multicomponent, and multilevel programs have been shown to be effective for employee health improvement, reduction in productivity loss, and generating a positive return on investment. Integrating a focused effort to reduce prolonged sitting time as a component of a comprehensive health promotion program is a good idea. It supports the overall program objectives and is consistent with the larger vision of improving employee health. Furthermore, insofar as prolonged sitting may affect only a portion of the workforce, the overall comprehensive program will present other employees with access to programs more appropriate for their jobs. Given that physical activity remains a mainstay of worksite health promotion programs, a variety of interventions that reduce sedentary behavior from a multitude of perspectives represents a long-term approach to improving and maintaining the health of employees.
References
1. Healy GN, Dunstan DW, Salmon J,
et al. Breaks in sedentary time: Beneficial associations with metabolic risk.
Diabetes Care. 2008;31(4):661-6.
2. Morris JN, Heady PA, Raffle CG, Parks JW. Coronary heart disease and physical activity of work.
Lancet. 1953;2:1053-7.
3. Owen N, Healy GN, Matthews CE, Dunstan DW. Too much sitting: The population health science of sedentary behavior.
Exerc Sport Sci Rev. 2010;38(3):105-13.
4. Patel AV, Bernstein L, Deka A, Feigelson HS, Campbell PT, Gapstur SM, Colditz GA, Thun MJ. Leisure time spent sitting in relation to total mortality in a prospective cohort of US adults.
Am J Epidemiol. 2010;172:419-29.
5. Physical Activity Guidelines Advisory Committee.
Physical Activity Guidelines Advisory Committee Report, 2008. Washington (DC): U.S. Department of Health and Human Services; 2008. Available from:
http://www.health.gov/paguidelines/. Accessed September 6, 2010.
6. Ramazzini B.
Diseases of Workers (1700, Latin). Translated by Wright WC. Chicago (IL): University of Chicago Press; 1940. p. 281-5.
7. Warren TY, Barry V, Hooker SP, Sui X, Church T, Blair SN. Sedentary behaviors increase risk of cardiovascular disease mortality in men.
Med Sci Sports Exerc. 2010;42(5):879-85.
