See lkrubner post http://news.ycombinator.com/item?id=2702904 for a link to http://en.wikipedia.org/wiki/Jerry_Morris which clearly indicates standing is not sufficient, exercise is necessary. (Please give lkrubner the karma points for posting the link first.)

From Wikipedia, "[...] sedentary drivers of London's double-decker buses had higher rates of cardiovascular disease than the conductors who climbed the stairs" and "[Jerry Morris] performed further studies that showed slow movements such as gardening helped very little and exercise had to be more vigorous to help."