Once the province of men in dark, smoky stadiums and shadowed by an image of violence, Thailand's ancient martial art of Muay Thai is being reborn, as a fitness regime.

Known as the country's national sport and said to be 2,000 years old, Muay Thai has seen a surge in popularity over the last five or so years, with gyms promptly taking advantage with state-of-the-art facilities mushrooming in Bangkok's most prestigious neighborhoods.

"Many Thais thought it was a violent sport so they were hesitant to send their kids to our school, but that's all changed thanks to international interest in the sport," said Phoemsakul Kesbumrung, general manager of Bangkok's Muay Thai Institute, which is dedicated to preserving the sport.

He should know. His school has grown from a handful of students in 1995 to 450 full-time students at present, with more signing up each year, and he has had to increase classes from 3 times-a-day, 6 days-a-week to 4 times-a-day, 7 days-a-week.

"Muay Thai isn't just about strength and lifting weights, it's also about training the mind to concentrate," he said.

"Muay Thai simply means 'Thai boxing.' It is also known as 'The Art of Eight Limbs' as hands, arms, elbows and knees are used extensively in this ancient sport that also mixes religious beliefs with traditional cultural practices.

Considered as much an artistic discipline as a sport, it includes a ceremony known as "Wai Kru" in which students pay respect to their teachers in a ritual that is considered an essential part of many ancient Thai disciplines including boxing, dance, Thai massage and astrology.

Foreign interest grew in the wake of films such as Tony Jaa's Ong Bak martial arts series, drawing a number of people to Thailand to pursue the sport.

Local celebrity endorsements and a string of home-grown boxing idols including two-time World MAX champion, Buaka Banchamek, a lightweight boxing champion, also helped boost interest. And Thai women and children are now taking up a sport previously dominated by men.

Children in particular are sent to both get fit and keep in touch with Thai tradition. One of Phoemsakul's students joined when less than 3-years-old and is still training.

Women hope to stay in shape and get rid of stress.

Sparring and spas

At The Siam hotel, General Manager Jason Friedman says that most guests who choose the hotel's one day and multi-day Muay Thai packages are female guests looking to firm up and blow off some steam in a unique way.

Guests are offered a unique Thai boxing lesson at the hotel's customized indoor ring followed by a pampering spa session to ease tired muscles at the hotel's opulent Opium Spa.

"We wanted the gym to be a core experience of the hotel and because of the rise in popularity of the Ultimate Fighting Championship, more people are hearing the words 'Muay Thai'" said Friedman.

Phoemsakul, at the Muay Thai Institute, has a steady stream of Muay Thai success stories to share, including one about an American expatriate living in Thailand who took up Muay Thai to lose weight after childbirth and ended up shedding 74 kilos over two years.

"From barely being able to run around the boxing ring, she was able to run 15 kilometers every day without getting tired," he said.

On a recent weekend, Natchanok Yochana was busy warming up for a Sunday evening women-only fight, watched over by her proud father, Nung Yochana, who said she used to sneak off to learn Muay Thai until he enrolled her at the school.

"I like the traditions behind Muay Thai and of course, I like to fight," said the lean 15-year-old, who practices twice a day and dreams big about her sport, smiling through her sweat.

"I'd like to go to the Olympic Games and represent my country. That would be the highest honor in my life," she said.