Lack of exercise costs world $67.5 bln and 5 million lives a year

* Physical inactivity linked to 5 million deaths a year * Sitting for eight hours or more raises mortality risk * Experts say at least an hour a day of exercise is ideal By Kate Kelland, Health and Science Correspondent LONDON, July 27 (Reuters) - A study of one million people has found that physical inactivity costs the global economy $67.5 billion a year in healthcare and productivity losses, but an hour a day of exercise could eliminate most of that. Sedentary lifestyles are linked to increased risks of heart disease, diabetes and cancer, researchers found, but activity - such as brisk walking - could counter the higher likelihood of early death linked with sitting for eight or more hours a day. Such inactivity is estimated to cause more than 5 million deaths a year - almost as many as smoking, which the World Health Organization (WHO) says kills 6 million a year.