Swimming star Ning finding his stride after retirement

China's former swimming world champion Ning Zetao has kept a low profile since his sudden retirement in March.

However, it seems that the 26-year-old has not totally abandoned the sporting life, with the pool ace challenging his endurance on land over weekend in the BMW Hood to Coast China Relay, around Zhangjiakou, Hebei province.

"As a retired swimmer, I can actually follow all sorts of sports now," said Ning, who only managed to finish part of the grueling 185km course. "It's a very different experience running in the relay.

"I have mostly just run alone on flat roads, but the relay is a combination of roads and muddy cross-country sections. It's very different from what I had imagined."

Ning shot to fame in 2015 by becoming Asia's first world champion in the men's 100m freestyle.

However, despite his professional athletic background, he still found the relay extremely tough going.

"I have to say that it's a lot more difficult than what I expected," said Ning.

"It was a huge challenge. I only experienced part of the track, but we chose the most difficult sections. I underestimated how hard it would be."

"As a pro athlete, aerobic fitness was not my focus - strength training and improving my skills were the priorities. Now, I'm making changes which will benefit my heart health."

Ning also said he enjoyed the team element of the race. One of his teammates was office worker Wu Ya, who usually participates in triathlons.

"The Hood to Coast relay and triathlon are both tests of endurance, but they are different," said Wu. "The relay's length and time are challenging. Luckily, it's a team sport.

"I learnt a lot, and the experience will in turn help me to improve in triathlon."

Zhang Jingkun, a biketrial enthusiast, was another member of Ning's team.

"All of the members in our team have sports experience, so it might seem like the relay should be easy for us. But that's not the case. It's hard," said Zhang.

"If you really like the sport, you should keep on doing it. More importantly, just enjoy it."