Regian Eersel reveals the secret behind his insane cardio

Aside from his world-class skills in the art of striking, what makes two-sport ONE world champion Regian Eersel extremely dangerous is his never-ending gas tank.

Those who shared the circle with “The Immortal” can attest to his godly fighting prowess, which is made even more lethal by his insane physical conditioning.

Eersel, of course, puts a lot of work behind closed doors to put himself in tip-top shape.

In an interview with Sensai Sam, the Surinamese-Dutch fighter, who is currently on a ridiculous 21-fight winning streak, said he still trains cardio the conventional way:

“Of course, running, everybody runs, you know. I think I do about 15 kilometers a week.”

Moreover, the Sityodtong Amsterdam product credited swimming as the main reason behind his seemingly unlimited vigor, adding:

“And I do swimming also with a professional swimmer and teacher. So it’s not like I’m going to the pool for a couple of minutes for a casual swim, it’s with a professional teacher who teaches you how to swim with good form and correct techniques.”

Watch the full interview below:

Swimmers, of course, are considered peaked-conditioned athletes in terms of overall endurance.

It’s no wonder a high IQ fighter like Eersel has adopted their training methods, given the exhausting nature of Muay Thai and kickboxing, especially at the highest level.

Eersel loves to bring his opponents into deep waters in the championship rounds and drown them with his insane output once they're already huffing and puffing.

“The Immortal” will once again put his amazing cardio to good use when he defends his ONE lightweight Muay Thai throne against Dmitry Menshikov at ONE Fight Night 11.

The entire card will emanate from the Lumpinee Stadium in Bangkok on June 9 and air live and free for Prime Video subscribers in North America.