Physical inactivity has a negative global impact so severe that its adverse effects on health are comparable to that of smoking or obesity, according to a new study.
What's more, the researchers say the problem of inactivity is so bad that it should be considered a pandemic.
Specifically, the scientists found that inactivity was responsible for 5.3 million out of 57 million deaths throughout the world in 2008, and it caused around one in 10 deaths globally, which is comparable to the effects of smoking. The researchers also, for the first time ever, analyzed and quantified the global impact of physical inactivity on some of the world's most prominent diseases.
In the first article, researchers from Brigham and Women's Hospital and Harvard Medical School estimated that a failure to spend at least 150 minutes per week doing moderate physical activity, such as briskly walking for 30 minutes, contributed to an average of 6 percent to 10 percent of several diseases worldwide, including type 2 diabetes, breast cancer, colon cancer and coronary heart disease.
"Physical inactivity and obesity both have deleterious effects on [these] diseases," Dr. I-Min Lee, a professor of medicine at Harvard Medical School and lead author of the study, told ABCNews.com. "Our findings described above examined the effects of inactivity, after taking into account the adverse effect of obesity. Thus, the results may be an underestimate of the true effect, since physical activity helps to control body weight."
If everyone did start participating in about the 30 minutes of moderate exercise per day, life expectancy throughout the world would increase by 0.68 years, Lee noted in the study.
Dr. George Flores, program manager for the California Endowment, weighed in on the series, and called it "timely" and "important."
Risk to health from inactivity is actually greater than the risk to health from being obese, he said.
"In the USA, the number of insufficiently active people is 50 percent greater than the number of obese people," said Flores. "That means that the opportunity to lessen risk for more people to a whole host of health problems is greater if we focus our attention on getting more people active instead of just focusing on obesity. Reducing inactivity is the single most promising opportunity to improve the health of the population at large."
Modern conveniences, including cars and computers, have contributed to the influx of physical inactivity in recent decades. Social isolation has also contributed to the shift to an inactive society.
Since the publication of the study "Actual Causes of Death in the United States," in 1993, Dr. David Katz, director of the Yale Prevention Center, said scientists have known that the three leading causes of premature death here are tobacco, poor diet and lack of physical activity.
Now, these data are becoming apparent throughout the modern world.
"Since 1993, tobacco exposure, here in the U.S., at least, has declined," said Katz. "So the relative contributions of feet and forks to the total burden of chronic disease and premature death has risen. And as labor-saving technologies proliferate across the globe, so, too, do the ill effects of sedentariness."
In the second study, Brazilian researchers showed that about one-third of adults throughout the world are at high risk of disease because of their lack of physical activity.
The researchers defined the recommended amounts of moderate activity as at least 30 minutes or more, five times per week, or vigorous activity for 20 minutes three times per week. They found that inactivity rises with age. It is more prevalent in high-income countries and is higher in women than men.
Of note, several low-income countries in Africa and the poorest regions of Latin America had inconclusive data to properly show inactivity rates for the study.
A third paper conducted by University of Tennessee researchers analyzed successful and promising interventions that can be used to work more physical activity into daily life.
"Because even moderate physical activity such as walking and cycling can have substantial health benefits, understanding strategies that can increase these behaviors in different regions and cultures has become a public health priority," Dr. Gregory Heath, lead author of the study, said in a statement.
After examining more 100 reviews of exercise interventions between 2001 and 2001, researchers found that the most successful ones included community exercise events and social support networks, such as buddy systems and walking clubs. Creating surrounding areas that are conducive to walking, biking and running encouraged people to get out and exercise more, and several studies showed that lighting and aesthetics of exercise areas can improve levels by up to 50 percent.
Whether technology or apps, running paths or lighted parks are available, Keith Ayoob, associate professor of pediatrics at Albert Einstein School of Medicine in New York said, it's important to "just move. Period."
"There's no substitute for low-tech moving, but there are apps and such that can motivate and help track," said Ayoob. "And we need to learn to decrease sedentary leisure activities. Sometimes you have to just power down to strengthen up."
With so many people throughout the world connected to mobile devices, there is indeed a place for apps. Researchers from the CDC found that text messages and other communications through mobile devices could successfully contribute to exercise interventions.
Finally, in a fifth paper, researchers said the prevalence of inactivity and its extreme effect on global health makes the problem a pandemic.
"The response to physical inactivity has been incomplete, unfocused, and most certainly understaffed and underfunded, particularly compared with other risk factors for non-communicable diseases," Dr. Harold W. Kohl, III of The University of Texas Health School of Public Health and lead author of the fifth paper, said in a statement.
Kohl and his colleagues noted in the study that exercise should be worked into a multifaceted system in society, through transportation, education, government, medical prevention and public health programs. Community-based efforts, rather than focusing on individual physicality, will be more beneficial in increasing exercise worldwide.
"The analysis here is convincing," said Katz of the Lancet series. "And common sense supports the conclusion reached by science: Failure to put our innate animal vitality through its native paces is taken life from our years, and years from our lives."