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.

The study is just one in a special series of reports in the journal Lancet, timed -- in an ironic twist -- to coincide with the Olympics.

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.