Like many Chinese athletes, Ms. Wu had been plucked from her family as an adolescent and sent to live at a state-financed sports academy, where training is grueling. Many athletes do not see their families for years. Last week, after Lin Qingfeng claimed a gold medal in men’s weight lifting, his father told reporters that he did not recognize his 23-year-old son, whom he had not seen for six and a half years, until he heard his name mentioned on television. “It’s been a long time,” Mr. Lin’s mother said, “since he’s had a meal at home.”

Yan Qiang, a veteran sportswriter, defended China’s emphasis on winning medals, saying they have helped to unify the nation. “We still need gold medals to boost social morale,” he said in an interview. “The people need it. And the athletes are willing to gamble their youth for a brighter tomorrow.”

The obsession with Olympic glory is inextricably tied to the country’s recent history. In the first half of the 20th century, Chinese intellectuals called their nation “the sick man of Asia,” lamenting its failure to produce Olympic-worthy athletes. Shortly after founding the People’s Republic of China, Mao Zedong sent a delegation of 40 men and women to the 1952 Summer Games in Helsinki, Finland; all but one arrived too late to compete.

In the decades that followed, China boycotted the Games to protest the participation of Taiwan, the breakaway island China still considers a province. It was not until the 1980 Winter Games in Lake Placid, N.Y., that Beijing returned to the Olympic fold.

In 1984, it won its first cache of gold medals during the Summer Games in Los Angeles. Still, in the years that followed, Chinese athletes struggled to make their mark beyond sports like pistol shooting, table tennis and badminton.

The Communist Party set out to change that in 2002, when it began Project 119, a program that uses prodigious state resources and relentless training to groom potential gold medalists in sports like swimming, gymnastics and track and field.

Dong-Jhy Hwang, a historian at the Graduate Institute of Physical Education at National Taiwan Sport University, noted that for many years China’s competitive fires were constrained by Mao, who proclaimed that during international sports events, friendship mattered more than competition.