Sedentary behaviors have been linked to obesity, diabetes, cardiovascular disease, and all-cause mortality. In terms of potential mechanisms, research has revealed associations between sedentary time and cardiometabolic risk factors, including higher waist circumference, higher blood pressure, unbalanced glucose and insulin metabolism, and unfavorable blood lipid profile.1
Television watching and its negative impact on health have been well-documented. A recent research study examined whether other types of sedentary behaviors netted a similar, deleterious impact on health. Specifically, the group of public health scientists sought to determine how cardiometabolic risk would be affected if individuals replaced their time spent doing one sedentary task with another sedentary task.2
The researchers examined data from the Coronary Artery Risk in Young Adults (CARDIA) Study—a cohort study including a diverse group of middle-aged adults recruited from four communities across America (Birmingham, AL; Chicago, IL; Minneapolis, MN; Oakland, CA). Through self-reported questionnaires, study participants (n=3,211) provided an estimate of time spent on six types of sedentary tasks (watching television, using a computer, completing paperwork, reading, talking on the telephone, and sitting in a car). Anthropometric data and fasting blood samples were collected for the analysis of a variety of cardiometabolic variables, from which a composite cardiometabolic risk score was estimated. Then, an analysis method known as isotemporal substitution paradigm was used to compare the different types of sedentary behavior in relation to cardiometabolic risk.2
- Time spent engaging in sedentary tasks was adversely associated with cardiometabolic risk, even after adjusting for physical activity
- Replacing time spent watching television with any other type of sedentary task significantly lowered the participant’s cardiometabolic risk
- Compared to other sedentary behaviors, television viewing produced the strongest, increased association with cardiometabolic risk
These findings suggest that reducing TV time may have a meaningful, beneficial public health impact on cardiometabolic health. However, the investigators cautioned that more studies are needed, as their cross-sectional data cannot infer causality and their study did not take into account the impact of sleep duration, sleep quality, and other potential confounders.
The study results were published in American Journal of Epidemiology (February 2018).
Why is this Clinically Relevant?
- Time spent engaging in sedentary tasks was detrimental to cardiometabolic health
- Among different sedentary tasks, television watching may pose the strongest cardiometabolic risk
- Clinicians should inform patients the health risks of sedentary behaviors and especially encourage patients to reduce time spent watching television
- Brocklebank LA, Falconer CL. Accelerometer-measured sedentary time and cardiometabolic biomarkers: A systematic review. Prev Med. 2015;76:92-102.
- Whitaker KM, Buman MP, Odegaard AO, et al. Sedentary behaviors and cardiometabolic risk: an isotemporal substitution analysis. Am J Epidemiol. 2018;187(2):181-189.