In 1940, Alvin “Shipwreck” Kelly sat atop a 225-foot flagpole in Atlantic City for 49 days and one hour. That took super-stamina and a skinny backside.

But according to a new study, sitting in front of the TV doesn't demand any physical prowess — and it's far worse for you than sitting at work.

Columbia University Medical School researchers found that participants who watched TV for four or more hours a day had a 50% greater risk of cardiovascular events and death over the course of the eight-and-half year study than those who tuned in less than two hours daily.

In contrast, those who sat the most at work had the same health risks as those who sat the least.

Why is sitting at work for six to eight hours less harmful than four hours a day of TV watching?

Well, when you watch TV, you don't move much — except to reach for a bowl of chips or ice cream. You may not even talk.

If you weigh 150 pounds, you're burning 68 calories per hour. But on the job, you'll burn 102 calories an hour while talking and 170 calories an hour doing moderate work.

So, to increase your calorie burn while watching TV, try chatting while riding a stationary bike. Here are some other things you can do to feel the burn:

• Sit up straight. Good posture demands engaged muscles.

• Laugh. Just 10 to 15 minutes of laughter can burn 10 to 40 additional calories.

• Drink water. One study found that drinking 16 ounces of water increases your metabolic rate by 30%, peaking at around 30 minutes after drinking.