18 Feb Prolonged Sitting Raises Cardiac Risk Factors in Post-Menopausal Women
MedicalResearch.com Interview with:
Dorothy Sears Ph.D.
Professor of Nutrition
College of Health Solutions
Arizona State University
MedicalResearch.com: What is the background for this study?
Response: Historically, heart disease among women has been understudied despite this being the number one cause of death in women. One in three women will die from heart disease. Older women are the fasting growing population in the US and after menopause experience a dramatic increase in risk for cardiometabolic diseases such as cardiovascular disease and type 2 diabetes. For these reasons, it is critical to understand the impact of modifiable behaviors on this risk. Accumulating evidence shows that prolonged sitting is a highly prevalent behavior, associated with cardiometabolic and mortality risk, and greatest in older adults. Thus, overweight or obese postmenopausal women who partake in prolonged sitting time likely have highly compounded cardiometabolic risk.
MedicalResearch.com: What are the main findings?
Response: In our overall study population (overweight/obese postmenopausal women), we observed an average sitting bout duration (a “bout” is a period of uninterrupted time) of 39 minutes and an average total sitting time per day of approximately 9 hours. These sitting time measures were significantly associated with cardiometabolic disease (heart and type 2 diabetes) risk factors, including greater body mass index, waist circumference, fasting blood sugar, insulin, and insulin resistance.
The strongest biomarker associations with the sitting measures were for fasting insulin and insulin resistance, which are important predictive and mechanistic biomarkers of risk for heart disease, type 2 diabetes, and cancer. As you can see, accumulation of greater sitting time, in bouts or across the day, is quite detrimental.
- Each additional hour of daily sitting time was linked with a more than 6% higher fasting insulin and a more than 7% increase in insulin resistance; and
- Each additional 15 minutes in average length of uninterrupted sitting period was associated with a greater than 7% higher fasting insulin and an almost 9% increase in insulin resistance.
Importantly, these associations were still significant after adjusting for exercise or for body mass index.
We also observed that Hispanic women sat for less total daily time and for shorter sitting bouts than non-Hispanic women. Interestingly, we found that the detrimental association between uninterrupted periods of sitting (sitting “bouts”) and fasting blood sugar may be greater in Hispanic women than in non-Hispanic women. This last finding needs to be corroborated in larger studies.
We controlled for confounding factors such as age, physical functioning, education, ethnicity, and marital status in our analyses, so these factors do not explain our findings. The associations persisted even when we controlled for exercise, meaning that the exercise participants conducted did not mitigate the negative effects of their sitting time.
(A sitting “bout” is a period of time that a person stays in the seated position without getting up)
MedicalResearch.com: What should readers take away from your report?
Response: Evidence from our study and that of others show that prolonged sitting time is a cardiometabolic health risk and should be discussed by clinical and healthcare professionals with patients. Clinicians and other health care providers should encourage patients to reduce their sitting time, total daily sitting time and uninterrupted bouts of sitting, in addition to encouraging physical activity. Other studies from our team and those of others suggest that, in older adults, replacing sitting time with standing or light activity may be health-promoting and, in practice, more feasible than with exercise. Accumulating evidence suggests that sitting time interruptions should be practiced throughout the day and need not be high intensity or long in duration.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
- Additional research in larger multi-ethnic/race populations is needed to validate whether sitting time impacts Hispanic women more negatively than non-Hispanic women.
- Sitting time is pervasive and negatively impacts people of all ages and sex so, research in populations across the lifespan is needed.
- Our study was a single time point cross-sectional study looking at associations. Studies with multiple timepoint measures over time are needed. We are engaged in three large controlled research studies that aim to reduce sitting time in sedentary postmenopausal women. We are very interested to see if cardiometabolic (heart and diabetes) risk is reduced in these women when their sitting time is reduced. These intervention studies will also inform us about what recommendations we can make to the public about how and how often to break up sitting time and support healthy aging.
This study, those of others and our on-going work could lead to public health guidelines related to workplaces providing standing desks for desk-job employees, social and community-based promotion of standing breaks, and how/how often to break up sitting time.
Our study was supported by funds from an American Heart Association Go Red for Women Strategically Focused Research Network grant and the National Institutes of Health.
Citation: ISC2020 Abstract
Ya‐Ju Chang PhD , John Bellettiere MA, MPH, PhD , Suneeta Godbole MPH , Samaneh Keshavarz BS , Joseph P. Maestas , Jonathan T. Unkart MD, MPH, MS , Daniel Ervin PhD , Matthew A. Allison MD, MPH , Cheryl L. Rock PhD, RD , Ruth E. Patterson PhD , Marta M. Jankowska PhD , Jacqueline Kerr PhD , Loki Natarajan PhD , and Dorothy D. Sears PhD firstname.lastname@example.org
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