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Prolonged sitting linked to cancer, study shows
Prolonged Sitting
Prolonged sitting linked to cancer, study shows - photo by Metro Creative Graphics

Exercise before or after a sedentary work day may not reverse the damage sitting has done already, a new literature review study says.

Daniela Schmid and Michael F. Leitzmann of the University of Regensburg in Germany looked at 43 observational studies, including 68,936 cancer cases, about the correlation between sedentary lifestyles and cancers. The authors found that the recommended amount of exercise — 150 minutes a week of moderate intensity aerobic activity and muscle-strengthening activities according to the Centers for Disease Control — will not undo the adverse effects of sitting.

The pair found that adults spend 50 to 60 percent of their day engaging in sedentary behaviors, including TV viewing,

“Adjustment for physical activity did not affect the positive association between sedentary behavior and cancer. This indicates that the increased risk of cancer seen in individuals with prolonged time spent sedentary is not explained by the mere absence of physical activity in those persons,” Schmid and Leitzmann wrote.

“Support is provided by observations of significant positive relations of TV viewing time to metabolic risk and mortality, even in physically active adults. That sedentariness has a detrimental impact on cancer even among physically active persons implies that limiting the time spent sedentary may play an important role in preventing cancer, even against the background of achieving the physical activity recommendations.”

Additionally, each two-hour per day increase in sedentary time was related to an 8 percent increased risk in colon cancer, a 10 percent increase in endometrial cancer risk and a “positive relation” between sedentary behavior and lung cancer.

The authors noted that TV viewing was often accompanied by other unhealthy behaviors such as eating unhealthy foods and smoking. As such, for every two hours a person increased their TV viewing time per day, researchers noted a 23 percent increased risk of obesity. By contrast, a two-hour per day increase of sitting at work increased one’s obesity risk by 5 percent.
“Sedentary behavior and obesity mediate risk for certain cancers (e.g., colorectal cancer and endometrial cancer) through shared mechanisms, whereas other cancers (e.g., breast cancer and renal cell cancer) show distinct obesity-specific pathways,” the authors wrote.

So in addition to regular exercise, what can people do to decrease their risk of sedentary-related cancer risk?

Get outside
Schmid and Leitzmann note in their study the importance of vitamin D in defending individuals against colon cancer.
“Vitamin D deficiency represents an additional biologic pathway through which sedentary behavior may contribute to cancer etiology. Vitamin D levels are lower in obese than normal weight individuals, and increased vitamin D levels are hypothesized to protect against colon cancer.”

The World Health Organization recommends sedentary employers allow employees to take time each day to expose themselves to vitamin D by walking around the campus of their work and encouraging active transportation such as walking or bicycling.

Get up
The Mayo Clinic recommends individuals incorporate action into watching television. Using hand weights, riding a stationary bike, stretching or simply getting up to the TV to change channels or the volume keep you from sitting for too long.
During the workday, use the popular 50/10 rule: work for 50 minutes sitting, then get up, stretch, walk to the drinking fountain, upstairs or around the office.

Individuals who work at a company that has a fitness facility on-site can take advantage of the opportunity to get active during lunch breaks or before and after work. If the weather is prohibitive to going outside, a slow pace on the treadmill or stationary bike in the fitness facility is a good fill-in.

Choose healthy snacks
Schmid and Leitzmann noted the detrimental snacking choices during TV viewing, but individuals can be conscious about their snacking. At work, if someone has a habit of running to the vending machine for an afternoon snack, try buying and preparing snacks before work. They can control portions, sugar, salt and fat intake easier when they are divvying out the portions themselves and allow themselves time to make a good choice.