LOS ANGELES, CA (Catholic Online) - In order to reap the benefits of sustained physical activity. The government advises about a half-hour of moderate activity a day for adults. In regards to the 23.5 hours of every day, researchers say it's important not to spend it sedentary or sitting.

Researchers recommend that physical activity and sedentary behavior independently affect your health and life expectancy. According to the author of "Sitting is Bad," Peter Katzmarzyk, professor of epidemiology at Pennington Biomedical Research Center Whether says that whether "you're physically active and meet the exercise guidelines, or if you're not active."

"Sitting is Bad" isn't Katzmarzyk's first study to document the ill effects of sedentary behavior. An Australian study published last August found that people who watched an average of six hours of TV a day lived 4.8 years less than those who didn't watch any television. In addition, every hour of TV that people watched after age 25 was associated with a 22-minute reduction in their life expectancy.

The recent analysis took a broader look, calculating the cumulative effect on overall life expectancy of a sedentary population.

Recent surveys show that worldwide people spend about 300 minutes, or 20 percent of their day, sitting; many people spend much longer. Shaving at least a couple of hours off that time could add years to life expectancy, the new study suggests.

Katzmarzyk and his colleagues pooled data from five studies that asked participants about their sedentary habits; including how much time they spent sitting, watching TV or using the computer screen. The researchers folded in the mortality risk associated with sedentary behavior, and then calculated how many years of life would be gained if these risk factors were removed from life expectancy calculations.

Sitting, it turns out, can shorten life expectancy almost as much as smoking can, which highlights just how damaging inactivity can be, particularly for the heart. "What the results mean is that we got everyone in the U.S. to sit less, our population life expectancy would be two years higher, so instead of living to 78.5, we would be expected to live to 80.5 years old," Katzmarzyk says. "That's a really big deal."

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