We’ve shared before about the importance of standing up from your desk instead of sitting all day. We’ve suggested you consider a standing (or standup) desk or to squat, or, well, lots of other things.

Why? Because more and more evidence is mounting that sitting all day is really, reall byad for us. As in, “associated with cancer” bad, according to research findings appearing in the Journal of the National Cancer Institute.

And here comes even worse news: Even those of you who exercise regularly before or after work don’t lessen the negative effects of 8-9 hours of uninterrupted sitting.

Why exercise won’t reverse the harmful effects of sitting all day

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(Hibr via: Flickr)

As with most large-scale surveys, the research did not claim that sitting causes death. However, it reinforced a mounting body of evidence that sitting is highly correlated to life-threatening conditions and diseases. But one thing the researchers discovered seems highly counter-intuitive:

When spending the same time at their desks as those who don’t exercise, those who exercise (before or after excessive sitting) don’t lower their risk of cancer. “(The results) indicate 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,” the researchers recently told Quartz.com.

Bottomline: If done at times other than when you’re at work, running or walking or any type of exercise is not enough to counteract all the harm that can result from uninterrupted sitting eight or nine or 10 hours a day. Here are some likely reasons sitting all day is bad, even if you exercise other times:

Your body is designed to move

“Sitting for an extended period of time causes your body to shut down at the metabolic level.” Marc Hamilton, Ph.D., professor and director of the inactivity physiology department (we can only imagine the jokes poked at a department with the word “inactivity” in it) at LSU’s Pennington Biomedical Research Center, told Runners World last year. When your muscles, especially certain leg muscles, are immobile, your circulation slows. So you use less of your blood sugar and you burn less fat, which increases your risk of heart disease and diabetes.

People are less active on days they exercise

Also from Runner’s World, this amazingly counter-intuitive statistic: People who work-out or run are 30 percent less active overall on days when they exercise versus days they don’t hit the road or the gym. “Maybe they think they’ve worked out enough for one day.”

Alternatives to sitting all day at your desk

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Simply interrupting your sitting time with short breaks of movement—just standing or walking slowly—has beneficial effects. In a 2008 study found who took more breaks (of just 4 1/2 minutes) from sitting had narrower waists, and lower body mass index, triglycerides and glucose tolerance—all important measures for obesity and metabolic health.

Try walking, a treadmill, or a treadmill desk

Research suggests improved glucose metabolism with one minute and 40 seconds of walking every 30 minutes for a nine-hour sitting period, as well as two-minute bouts of light-intensity treadmill walking every 20 minutes throughout a five-hour sitting period. Getting up and walking around at least twice an hour can keep your skeletal muscles turned on and lower the risk of disease. Be like Steve Jobs and have walking meetings.

Buy, build or rig-up a standing desk

Try a standing (or standup) desk. In addition to the collection of desks we’ve written about, we’ve created a Board at Pinterest.com/SmallBusiness filled with examples of standup desks, from DIY (free) to really awesome (expensive).

Share your ideas: Do you have a favorite way to break up your all-day sit-athon? Share it on the comments below.

(Photo illustration: SmallBusiness.com, Photo: Thinkstock)