More evidence that exercise will lengthen your life; and television shorten it

Here's an eight year study of 400,000 persons in Taiwan -

The people in the low-activity group exercised for an average of 92 minutes per week, or just under 15 minutes a day. Compared to those in the inactive group — who did almost no physical activity — those in the low-activity group were 14 percent less likely to die from any cause, 10 percent less likely to die of cancer, and had a three-year longer life expectancy, on average.

Every additional 15 minutes of daily exercise beyond the minimum 15 minutes further reduced the risk of all-cause death by 4 percent and the risk of cancer death by 1 percent.

The benefits of even low levels of physical activity were seen in all age groups, in both men and women, and in people with cardiovascular disease risks.

The study appears online Aug. 15 in The Lancet.

But television? Not so clever.

Researchers in Australia found that people who averaged six hours a day of TV lived, on average, nearly five years less than people who watched no TV.

For every hour of televisionwatched after age 25, lifespan fell by 22 minutes, according to the research led by Dr. J. Lennert Veerman of the University of Queensland.

But other experts cautioned that the study did not show that TV watching caused people to die sooner, only that there was an association between watching lots of TV and a shorter lifespan.

Though a direct link between watching TV and a shortened lifespan is highly provocative, the harms of TV are almost certainly indirect, said Dr. David L. Katz, director of the Prevention Research Center at Yale University School of Medicine.

"As a rule, the more time we spend watching TV, the more time we spend eating mindlesslyin front of the TV, and the less time we spend being physically active," Katz said. "More eating and less physical activity, in turn, mean greater risk for obesity, and the chronic diseases it tends to anticipate, notably diabetes, heart disease and cancer."