February 2020, Issue #2 Sedentary Behavior and Health

Biswas, Aviroop, BSc, Oh, PI, MD, MSc, Faulkner, Guy E., PhD, et al., Sedentary Time and Its Association with Risk for Disease Incidence, Mortality, and Hospitalization in Adults, Annals of Internal Medicine, 2015; 162:123-132.

Diaz, Keith, PhD, Howard, VJ, PhD, Hutto, B, MSPH, et al., Patterns of sedentary behavior and mortality in U.S. middle-aged and older adults: A national cohort study, Annals of Internal Medicine, 2017; 167(7):465-475.

Rawlings, GH, Williams, RK, Clarke DJ, et al., Exploring adults’ experiences of sedentary behavior and participation in non-workplace interventions designed to reduce sedentary behavior: a thematic synthesis of qualitative studies, BMC Public Health, 2019; 19: 1099.


November 2019,  Issue #1 The Inactivity Problem


Du, Yang, MD, MS; Buyun Liu, MD, PhD; Yangbo Sun, MD, PhD; et al. “Trends in Adherence to the Physical Activity Guidelines for Americans for Aerobic Activity and Time Spent on Sedentary Behavior Among US Adults, 2007 to 2016.” JAMA Network Open. 2019; 2(7):e197597. doi:10.1001/jamanetworkopen.2019.7597

Background. The 2018 Physical Activity Guidelines agreed with and extended the results from the 2008 Guidelines that found U.S. adults needed to increase aerobic and other activity. These reports showed that being inactive was leading to many poor health outcomes, including falls.

Du and his research team asked, “Over the decade between reports, how much has the U.S. population complied with the recommendations for aerobic activity of about 150 minutes per week?”

Also, the 2018 recommendations noted that sedentary behavior (extended time sitting) had an independent association with health outcomes, meaning that more sitting is associated with worse health, regardless of other activity. The researchers asked, “Over this same decade, how sedentary was the U.S. population?”

Data from the US Centers for Disease Control and Prevention’s National Health and Nutrition Examination Surveys (CDC/NHANES) provided evidence from 27,343 adults to answer these questions. NHANES participants are a statistically representative sample from the non-institutionalized US population age 18 and over.

Results. For all ages, findings showed no statistically significant change over time in the proportion of the U.S. population in compliance with the aerobic activity recommendations, about 63.2% in 2008 and 65.2% in 2016. For adults ages 65 and older, even fewer, about half (49.1%) were compliant with aerobic activity recommendations in the most recent survey (2015-2016).

For sedentary behavior, the findings for all adults showed a worsening situation: 5.7 to 6.4 hours per day (2008 to 2016, respectively). During this time period, older adults were generally consistent in reporting about 6 hours. Reducing the effects of sedentary behavior on health is the subject of an upcoming News from Science.

Looker, Anne C. and Wang, Chia-Yih, Prevalence of Reduced Muscle Strength in Older U.S. Adults: United States 2011-2012. NCHS (National Center for Health Statistics) Data Brief, No.179, January 2015.

Looker and Wang examined the weakening of muscle strength as a function of age. They also examined differences by gender and race/ethnicity. They noted the associated between strength and functional capacity for getting out of a chair.

U.S. Department of Health and Human Services. 2008 Physical Activity Guidelines for Americans

This report was developed to address the national problem of inactivity and poor health outcomes. When the expert panel examined all research in this area, they concluded that health improvements required aerobic activity (about 150 minutes per week) and strength-building (twice a week). Also, for older adults, balance exercises were recommended to address falls risk. This report was more cautious about older adults, suggesting they should be as active as their abilities and conditions allow.

U.S. Department of Health and Human Services. Physical Activity Guidelines for Americans, 2nd edition, Washington, DC: published online April 17, 2018.

This report was a follow up to the 2008 Guidelines. It concurred with the earlier exercise recommendations and extended the findings in several areas. The 2018 report emphasized the benefits of physical activity, including balance exercises, for all older adults. Findings showed physical activity was linked to less fall-related injury, including fewer falls and when there was a fall, less severe injuries.

The panel also noted:

“Physical activity is key to preventing and managing chronic disease.” The evidence was strong for a positive association between activity and: risk of early death, coronary heart disease, stroke, high blood pressure, adverse blood lipid profile, type 2 diabetes, metabolic syndrome, colon cancer, breast cancer; prevention of weight gain, weight loss, improved cardio-respiratory and muscular fitness, prevention of falls, reduced depression, and better cognitive function.”

Additional evidence was at least moderate for positive health outcomes with lower risk of hip fracture, lung cancer, endometrial cancer; weight maintenance, increased bone density, and improved sleep quality; better functional health, and reduced abdominal obesity.

The recommendations added a focus on reducing sedentary behavior that is separate from and in addition to recommendations for increased physical activity.

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