TV Shortens Your Life
In the journal Circulation, researchers reported on data collected from 8,800 Australian men and women (over age 25 with no history of heart disease). Individuals were surveyed on a number of lifestyle factors including their television viewing for a week. The study participants also reported their overall activity levels and took tests for oral glucose and cholesterol levels. The study ran for six years. Over that period of time, 87 people in the study had died from cardiovascular disease and 125 had died from cancer.
When researchers analyzed their data, they grouped people by how many hours of TV they watched each day. What they found was that every hour of TV watching increased a person's risk of dying from cardiovascular disease by 18%, increased overall risk of death by 11%, and increased the risk of death from cancer by 9%.
In other words, people who watched more than 4 hours of TV a day (the average in the U.S.) had an 80% increased risk of death from cardiovascular disease over the 6-year time period when compared to people who watched 2 hours or less each day.
But Is It Really TV That Harms Health?
Researchers controlled the study for obesity and overweight, high blood pressure, high cholesterol and exercise levels. That means they used statistics to factor out those variables in order to isolate TV watching. The numbers reported above are after the other variables were controlled for. In other words, whether you exercise or not -- too much TV is bad for your health.
Rethinking "Sedentary Behavior"
Another article, published in BMJ Sports Medicine, challenges us to rethink the term "sedentary behavior." Instead of focusing on exercise time (e.g., "I exercise 30 minutes a day"), we should think about minimizing periods of "muscular inactivity." This new term simply means time spent doing nothing. I may exercise 30 minutes a day, but if I spend the rest of my day sitting at a computer or watching TV, my level of "muscular inactivity" is still too high. I like this way of rethinking our daily activity. Too many people exercise some and then think that justifies sitting around the rest of the time (I know this is true, because I am one of those people). So by looking at total "muscular inactivity" time, we may make some behavioral changes that lead to greater health.Long-Lived Peoples
This whole perspective of "muscular inactivity" really makes sense when we think about the people with the greatest longevity. Generally, the most long-lived people in the world don't exercise very much, but they also have very little "muscular inactivity" in their day. They spend their time walking, doing chores, cooking and gardening (but no formal "exercise"), and they live longer and age better than the rest of us.A Muscle Inactivity Challenge
Give this a try -- for one week, count the number of minutes you exercise AND count the number of minutes you spend in "muscular inactivity," such as watching TV. When I did this for myself, I was shocked. I spend hours and hours in "muscular inactivity" every day (sitting at the computer, driving and watching TV). Time for more gardening, chores and walking for me!Sources:
Dunstan DW, Barr EL, Healy GN, Salmon J, Shaw JE, Balkau B, Magliano DJ, Cameron AJ, Zimmet PZ, Owen N. "Television Viewing Time and Mortality. The Australian Diabetes, Obesity and Lifestyle Study" Circulation. 2010 Jan 11.
Editorial. British Journal of Sports Medicine. January 2010
