To complete the Spartan Race, you need to be able to run long distances, and also have strong muscular endurance.[Photo by Wei Xiaohao/China Daily]

As the founder of the CrossFit gym in Beijing, Xu also brought 40 of her gym members to join her public group. "I wanted to show them that gym is not the only way of doing exercise - you can do all kinds of sports."

According to Xu, the Spartan Race can be a good way for people to identify their physical weaknesses, as different obstacles require different skills to complete them.

Richardson Manzol, who comes from Venezuela, is another Spartan ambassador. He led a team to run the Super Race an hour after he finished the Elite group event, and the following day, he returned to lead a vegan team in the Spartan Sprint competition.

Manzol says he has fallen in love with the event. "I took part in the Spartan Race in 2016, and I'm married to it now," says Manzol, who completed his trifecta last year.

"It's just like being a kid again. You are in a huge playground full of obstacles and you're allowed to get dirty," Manzol says.

Manzol has been a vegetarian for six years, and became a vegan two years ago. After learning about nutrition, Manzol realized that there were many other sources of protein other than meat and dairy, so he decided to adopt a vegan lifestyle.