Sitting has become epidemic in the United States, with Americans sitting an average of eight to 13 hours a day. Research that shows just how bad sitting is for us is mounting by the day. Here are some of the numbers:

7.7 hours: Average time we sit while commuting and at home.

83 percent: Rise in sedentary jobs since 1950.

3 hours: People who sit three hours less a day can add three years to their life expectancy.

54 percent: Those who sit for most of the day are 54 percent more likely to die of a heart attack.

60 calories: People who stand burn an average of 60 more calories an hour than sitters.

2 hours: Every two hours spent sitting reduces blood flow, raises blood sugar and reduces good cholesterol by 20 percent.

Sources: American Journal of Epidemiology study;; Medicine & Science in Sports & Exercise.