Wales's rugby squad have turned to yoga in preparation for the World Cup in New Zealand in September.
Catherine Kelleher was contacted by the Welsh Rugby Union after it heard about her 'hot yoga' classes in Cardiff.
She said the heated environment requires no warm-up and benefits players who are tired after training.
"I've been very surprised at how well they've taken to it," she said. "I think they enjoy the relaxation at the end of a few tough days."
Ms Kelleher claims to be the first practitioner in Wales of hot yoga, which combines elements of a range of yoga techniques in temperatures of up to 34 degrees Celsius (93.2F).
Former Wales rugby star Jonathan Davies is among those who have attended her classes in the last year.
She said the lack of the need of a warm-up allows people to go much deeper into stretches and into connective tissue, and is particularly helpful for sportsmen and women.
"It allows their muscles to relax," said Ms Kelleher of the warm temperature.
"When the guys come to me they've already done a few days quite hard training.
"Their bodies are quite fatigued anyway so it's of benefit to them to do stretching in a heated environment, because to come to a cold class, they would find it quite difficult to get into the depth of stretch we'd want them to get into.
"It's also beneficial in recovering from injuries - it allows us to work in stretches to help injured parts of the body which we would struggle to get into in a cold environment.
Ms Kelleher said the focus of her sessions with the rugby squad was more on training and recovery, and less on the spiritual side of yoga.
'Little bit susceptible'
"People are drawn to it who want a stronger session - it's the mindset that it's a bit tougher," she said.
"I've been very surprised at how well they've taken to it. They seem to have loved it - numbers have gone up since we started.
"I think they enjoy the relaxation at the end of a few tough days."
The idea to do hot yoga came from the WRU's head conditioning coach Adam Beard, who said the players had really taken to the idea and were volunteering to take part.
"We hand-picked six guys who we thought were a little bit susceptible to injury and not as flexible," he told the Western Mail newspaper.
"We put those six in and then said to the others it's not compulsory, but we ended up having to knock the guys back, because we can only fit 10 in the room."
Tennis stars Andy Murray and Venus Williams have tried a version of hot yoga, along with players from Chelsea and Fulham football clubs.
Former Wales captain and Manchester United footballer Ryan Giggs has also revealed that taking up yoga had helped him prolong his sporting career into his late thirties.