A new study in the journal The Lancet shows just how big of a toll physical inactivity takes on our health -- and how its relationship with death may be comparable to that of smoking.
Researchers from Brigham and Women's Hospital and Harvard Medical School found that not engaging in moderate exercise for 150 minutes a week (what is recommended by the Centers for Disease Control and Prevention) was linked with 5.3 million deaths worldwide in 2008 -- about 9 percent of all deaths.
"With elimination of physical inactivity, life expectancy of the world's population might be expected to increase by 0.68 years," researchers wrote in the study. "These findings make inactivity similar to the established risk factors of smoking and obesity."
(Researchers noted that that additional 0.68 years seems low because that figure was calculated taking into consideration both active and inactive people.)
The researchers analyzed past studies on the effects exercise has on the risk of different diseases. They found that not engaging in the recommended exercise levels was the main cause of 6 to 10 percent of coronary heart disease, breast cancer, colon cancer and Type 2 diabetes cases around the world.
Specifically, not meeting the recommended exercise levels was linked with 6 percent of coronary heart disease cases, 7 percent of cases of Type 2 diabetes, and 10 percent of cases of colon and breast cancer.
The CDC recommends that adults get at least 150 minutes per week of a moderate aerobic exercise -- like walking briskly -- plus two or more days of muscle-strengthening activities. Or, another recommended combination is 75 minutes per week of vigorous aerobic exercise -- like running -- along with two or more days of muscle-strengthening activities. Yet another recommended combination is doing a mix of vigorous and moderate aerobic exercises along with the two days or more of muscle-strengthening exercise.
And you don't need to do all that exercise in one sitting: The CDC says that doing just a bit at a time -- even 10 minute increments -- can help you achieve recommended exercise levels.
For some exercises that have been linked to living a longer life, click through the slideshow:
In 2008, a small Swiss study found that sedentary people who switched from taking escalators and elevators to taking the stairs cut their risk of dying prematurely by 15 percent. "This suggests that stair climbing can have major public health implications," lead researcher Dr. Philippe Meyer, told the BBC. An earlier look at data from the Harvard Alumni Health Study also found that climbing 35 or more flights of stairs a week significantly increased longevity when compared to people who climbed fewer than 10 stories a week. Flickr photo by mariachily
Biking to work is a great way to squeeze exercise into your day, spend some time outside and even save on gas money. But a leisurely ride, while it might leave you less sweaty upon arrival at the office, won't do as much for your lifespan as if you really ride it out. A study of Copenhagen cyclists found that men who pedaled the fastest lived more than five years longer than slower cycling men, and the fastest women cyclists lived almost four years longer. Flickr photo by terren in Virginia
A 2009 analysis of data from the Aerobics Center Longitudinal Study found that men who swam regularly had about a 50 percent smaller risk of dying than sedentary men -- but swimmers also had a lower mortality rate than men who walked and ran for their exercise. Flickr photo by West Point Public Affairs
A 2011 study found that people who naturally walk at a pace of one meter per second, about 2.25 mph, or faster, lived longer than their slower peers. But walking pace might be more of an indicator of longevity rather than a way to increase it, the study's author cautioned. "Your body chooses the walking speed that is best for you, and that is your speed, your health indicator," lead researcher Dr. Stephanie Studenski told MyHealthNewsDaily. "Going out and walking faster does not necessarily mean you will suddenly live longer," she said. Flickr photo by Justin Scott Campbell
Some think to get the full benefit of a good workout, you need to be sweating for a full 30 minutes -- or longer. But with so many people struggling to find a spare 30 minutes, researchers have begun to investigate if a shorter sweat session could be just as good. A 2011 study found when compared to sedentary people, 15 minutes of daily activity, like brisk walking, added three years to life expectancy, according to Reuters. Flickr photo by lululemon athletica
Walking faster, cycling harder -- there's an underlying theme to many of the benefits of exercise: intensity. Overall, vigorous activities seem to have more life-lengthening powers than nonvigorous activities, according to a 1995 study. In fact, intense exercise may double the years added by moderate exercise, according to a 2005 study. Five days a week of walking for 30 minutes led to 1.3 to 1.5 additional years, The Washington Post reported, but intense exercise, like running half an hour five days a week, resulted in 3.5 to 3.7 extra years. Flickr photo by frankjuarez