The Spartan Race endurance series is urging more Chinese warriors to join its legion.

Founded in 2005, Spartan Race features a series of obstacle races of varying distances and difficulty, ranging from six kilometers to a full marathon.

It has grown from strength to strength after being introduced to China by sports marketing company SECA in 2016.

"For the past two years, we've witnessed the birth of many Chinese Spartan warriors," said Yu Lei, the senior vice-president of SECA.

"Spartan Race is gradually becoming a lifestyle which encourages people to keep pushing themselves mentally and physically."

With the new slogan "Push Harder", the 2018 Spartan Race will feature over 20 events across China which are expected to attract over 100,000 competitors. There were just four events in 2016 and nine last year.

Spartan Race, which has been franchised to 30 countries, features events such the Spartan Sprint, the Super Spartan, the Spartan Beast and the Ultra Beast, as well as a new kids' race introduced last year.

Through the kids' race, which is open to children aged 4 to 14, organizers say they hope to build more "Spartan families" in an increasingly fitness-focused China.

The series also announced five race ambassadors have been appointed to represent the "warriors".

"The race is a good way to release the pressure of my work and help live a lifestyle that I want to have for the rest of my life," said Lu Zhengyu, one of the ambassadors, who works as a scientist.

The 2018 Spartan Race is also being supported by automobile company Infiniti and Chinese sportswear brand Anta.

The series counts tennis superstar Serena Williams and her husband, Reddit co-founder Alexis Ohanian, among its famous finishers after the pair completed a Spartan Race together in January in the US.

"Competed in a Spartan race this weekend with some of my @kryptonian teammates," the 36-year-old wrote online at the time.

"This first video was a 5.5-foot jump. Halfway through I knew there was no chance to get my legs over so I remembered my gymnastics classes from my youth!"