One potato, two potato, three potato.
An effort to count the world's sloths.
A PAPER in the Lancet, shamelessly timed to coincide with the Olympic games, compares countries' rates of physical activity. The study it describes, led by Pedro Hallal of the Federal University of Pelotas, in Brazil, is the most complete portrait yet of the world's busy bees and couch potatoes. It suggests that nearly a third of adults, 31%, are not getting enough exercise.
That rates of exercise have declined is hardly a new discovery. Since the beginning of the industrial revolution, technology and economic growth have conspired to create a world in which the flexing of muscles is more and more an option rather than a necessity. But only recently have enough good data been collected from enough places to carry out the sort of analysis Dr Hallal and his colleagues have engaged in.
In all, they were able to pool data from 122 countries, covering 89% of the world's population. They considered sufficient physical activity to be 30 minutes of moderate exercise five days a week, 20 minutes of vigorous exercise three days a week, or some combination of the two.
There are common themes in different places. Unsurprisingly, people in rich countries are less active than those in poor ones, and old people are less active than young ones. Less obviously, women tend to exercise less than men—34% are inactive, compared with 28% of men. But there are exceptions. The women of Croatia, Finland, Iraq and Luxembourg, for example, move more than their male countrymen.
Malta wins the race for most slothful country, with 72% of adults getting too little exercise. Swaziland and Saudi Arabia slouch in close behind, with 69%. In Bangladesh, by contrast, just 5% of adults fail to exercise enough. Surprisingly, America does not live up to its sluggish reputation. Six Americans in ten are sufficiently active by Dr Hallal's definition, compared with fewer than four in ten Britons.
In an accompanying analysis of people's habits, Dr Hallal found equally wide differences. In South-East Asia fewer than a quarter sit for at least four hours each day; in Europe 64% do. And even neighbours may differ. Only 2% of Swiss walk to work, whereas 23% of Germans do so.
These high rates of inactivity are worrying. Paradoxically, human beings seem to have evolved to benefit from exercise while eschewing it whenever they can. In a state of nature it would be impossible to live a life that did not provide enough of it to be beneficial, while over-exercising would use up scarce calories to little advantage. But that no longer pertains. According to another paper in the Lancet, insufficient activity these days has nearly the same effect on life expectancy as smoking.