Actually, if you rank a nation's sporting prowess by how many Olympic gold medals it wins per capita, Jamaica - which won 2.2 gold medals per 1 million inhabitants - is, hands down, the supreme sports power on the planet. China, with a population of 1.3 billion, ranks 47th, and the US, with 305 million people, 33rd. Such calculations may seem flippant, but they also point out the dubiousness of equating a country's Olympic performance with its standing as a nation - athletic or otherwise.
The reason Chinese athletes achieved such glory is not the general fitness and athletic talent of its people. Rather, it is China's large and expensive scouting and training system, reminiscent of those in the former Soviet Union and East Germany, that selects children as young as five for Olympic training and turns them into state-sponsored athletes. Also, particularly for this past Games, in which the host was determined to shine, the Chinese sports bureaucracy chose to target sports that offer relatively weak international competition.
Meanwhile, however, the real China, in stark contrast to the Olympic China, exercises little and, perversely, seems to be getting fatter in the cities while remaining undernourished in the countryside. With spectacular images of the "Bird's Nest" and the "Water Cube" still lingering, it is easy to forget that most Chinese continue to live in rural areas, where poverty and malnourishment are commonplace. At the same time, in the burgeoning cities, American-style obesity has become a problem.