Liu emerged as Asia’s first Olympic gold medalist in the 110-metre hurdles at the 2004 Athens Olympics. He also ranks as the continent’s first world champion hurdler.

A nagging tendon injury caused the Shanghai native to limp off the track when Beijing hosted the Summer Games in 2008. He retired from the sport this April, blaming his longstanding injury.

Now scientists from Liu’s hometown believe they have found a way to restore him to full health, along with millions of other patients bearing muscle-related injuries.

“Muscle stem cells are the ultimate way to cure muscle-related wounds or diseases,” said Hu.

“Our technology would not only benefit athletes, but also address a wide range of medical issues such as treatments for people involved in car accidents, those who have had surgery for cancer, or sufferers of amyotrophic lateral sclerosis (ALS).”

By transplanting the stem cells from the test tube back into the patient’s body, new muscles can regenerate in the area that was injured or malfunctioning, she said, adding that a return to full physical capability was likely.

The problem is the paucity of such stem cells. Even though the cells can be extracted from healthy muscles fairly easily, large wounds require large numbers to be dragged over from healthy parts of the patient’s body, which poses more of a risk, Hu said.

For decades, researchers around the world have tried to grow muscle stem cells independent of a human carrier so that large numbers could be harvested without jeopardising the patient’s health. All previous attempts have failed.

Scientists found the stem cells were either reluctant to divide in the test tube, meaning they were unable to multiply, or that they lost viability after being transplanted.

In two months, Hu's team, which included professor Wang Hongyan, managed to harvest 10 trillion muscle stem cells from a pool of just 10,000 original stem cells taken from the host. Moreover, the newly created versions were almost as effective as the originals in terms of regenerating muscle.

The study took over two years but success came faster than the team expected. The key was to find which proteins would best stimulate growth in the test tube out of a list of 10,000 possible candidate proteins, Hu said.

“It was like looking for a needle at the bottom of a lake,” she said.

They locked down four proteins that served as messengers between cells and which were able to stimulate the growth of the cell in an artificial environment.

This technology may have huge potential in clinical applications as muscles do not heal easily when left to their own devices. If a patient loses more than 20 per cent of the tissue in a functioning area, the damage would be permanent, Hu said, adding that no cure was available – until now.

The professor said a similar method could be used to grow tendon stem cells to treat injuries like Liu’s.

She added that although tests on mice showed that the test tube-generated cells were almost identical to the natural cells, extensive clinical trials would be needed to reduce the risk of side effects on humans, such as mutations that could lead to tumours. Such trials are crucial as safety is of paramount importance.

The team has contacted hospitals in China about conducting human trials but has struggled to find volunteers, partly due to financing and partly because Chinese are less interested in sport than people in Western countries, Hu said.

“Most people in China don’t care about muscle injuries until they find they cannot walk,” she said. “Some people could not understand the importance of this study.”