The Global Impact of Physical Inactivity
With the summer Olympic Games coming up, a group of 33 researchers from 16 countries worldwide felt this was a good opportunity to call the attention of the world to the public health problem of physical inactivity. Since physical activity has so many health benefits, it is concerning that only about one-third of the world’s population is physically active.
How much of a health problem does this pose worldwide? I was part of a group of researchers who, for the first time, identified the global impact of physical inactivity on the world’s major non-communicable diseases (NCDs). Our work , published as part of a special series on physical activity in The Lancet, found that physical inactivity, which is defined as being active for less than 2 ½ hours per week doing a moderate-intensity activity like brisk walking (or one hour and fifteen minutes of a vigorous-intensity activity like jogging), has become a contributor to the burden of disease similar to tobacco smoking or obesity.
My colleagues and I looked at what impact physical inactivity has on coronary heart disease (CHD), type 2 diabetes, and breast and colon cancer – diseases that the United Nations has deemed as threats to global health. We found that between 6 and 10 percent of these diseases worldwide is caused by physical inactivity. Physical inactivity is responsible for 5.3million of the 57 million deaths that occurred globally in 2008. That means physical inactivity is responsible for about 1 in 10 deaths worldwide. If every inactive person in the world were to become active, the life expectancy of the global population would increase by 0.68 years.
What do these numbers mean? For comparison, let’s look at smoking, a widely accepted risk factor for poor health. Smoking is estimated to cause about 5 million deaths worldwide each year. Thus, inactivity and smoking are comparable, in terms of the number of deaths they cause. However, unlike smoking and other risk factors including poor diet and alcohol, physical inactivity is a neglected dimension of prevention and intervention worldwide.
Part of that prevention means doing 2 ½ hours a week of moderate-intensity activity. What do we mean by moderate-intensity? A good way to gauge your intensity level is this: you are working at moderate-intensity if you can still carry on a conversation, but don’t have enough breath to sing. What activities count? Anything that gets you moving at a moderate-intensity, including: cycling to work, dancing in your living room, tending to your lawn or garden, doing water aerobics with friends, walking your dog, or even playing with your children or grandchildren.
Many of us will admire the breathtaking feats of athletes competing in the Olympics. Although only the smallest fraction of the population will attain these heights, the overwhelming majority of us are able to be physically active at very modest levels – such as 15–30 minutes a day of brisk walking – which still yield substantial health benefits.**
To help motivate you to make physical activity a part of your everyday life, sign up for the Presidential Active Lifestyle Award (PALA+) at www.presidentschallenge.org .
Dr. I-Min Lee is a member of the President’s Council on Fitness, Sports & Nutrition (PCFSN) Science Board and a professor at Brigham and Women’s Hospital and Harvard Medical School.
* Obesity is defined as having a BMI of 30 or higher. Generally, this would be someone who is 5’9” and weighs 203 pounds or more. It is important to remember that BMI cannot account for differences in muscle mass and fat mass.
**The information covered here is for the adult population aged 18 and older. Children and adolescents ages 6-17 need to be active at least 60 minutes a day.