During her fourth yoga class, Yvonne Kong attempted a seated twist to stretch her spine. She couldn't turn as far as the rest of her class, so the instructor pushed her into the position.
The Hong Kong hairdresser immediately felt a sharp pain in her lower back, which persisted after the class. She visited a chiropractor the next day to begin a course of treatment.
Kong, aged 40, said she had never checked whether the instructors were qualified to teach yoga.
"I thought they should be or they wouldn't be teaching," she added.
As in many Asian cities, yoga has boomed in Hong Kong over the past few years, but according to some students and medical pracitioners there has been a corresponding spike in injuries.
"Yoga keeps us in business," said chiropractor David Cosman.
The popular exercise, which originated in India, combines meditation with a series of poses meant to improve strength and flexibility.
It has become the workout of choice for many Hong Kongers in high-pressured jobs as they seek to ease the stress of city life, leading to the establishment of an increasing number of yoga studios.
The Pure Yoga centre opened its first 4,000 square-foot (372 square-metre) studio in Hong Kong in 2002. Now, the chain's largest studio is 35,000 square feet and it has since expanded globally, with branches in Taipei and New York City.
The city hosts a huge yoga conference every year, and magazines are packed with adverts promoting different styles or studios.
"The busy lifestyle in Hong Kong allows time to perform only one or two hours of exercise a day and they choose yoga because it seems less harsh," said Elton Ng, a physiotherapist specialising in the treatment of sports injuries.
Cosman said the yoga craze has brought his office a steady stream of visits from injured enthusiasts. The most common complaints are of lower back and neck pain.
Eleanor Kee, a chiropractor who works in Causeway Bay said that 20 percent of all her current patients were injured through yoga.
"One of the reasons people injure themselves is that they don't realise (yoga is) more than just some relaxing technique, it's a practice people take years to perfect," she said.
Often, she said, she encounters injuries caused by an instructor forcing a student into a pose.
Chiropractor Heidi Petrick said it is important for students to check that instructors have the proper certification.
There is a temptation, she said, for fitness centres to offer yoga classes simply because there is such a high demand.
"There is a strong danger in people having too much faith... when putting your body in someone else's hands," she said.
Carrie Chan had been doing yoga for three years. Around two months ago, she changed her warm-up routine from running to working on a stepper.
When she later attempted a simple stretching pose during her yoga class, the 37-year-old felt a sharp pain.
"I heard a sound from my hamstring, like a broken sound," said Chan, who works as a team manager at an insurance firm.
Chan said she could hardly walk or sit afterwards and had to go three times a week for three weeks to her chiropractor to relieve the pain.
There have been several personal injury lawsuits filed by yoga students against studios around Hong Kong.
In 2002, Ma Yuen-wah sued the exercise chain California Fitness for an injury she sustained at one of their branches.
The chain's spokesman Ken To would not comment on the court case, but said the firm held regular workshops and ongoing training to maintain and improve the skills of its staff.
In December 2008, a judge ruled that Yoga Plus had to pay more than 300,000 Hong Kong dollars (38,000 US) to a former student who had to be hospitalised after practising yoga for the first time at the company's studio.
Yoga Plus closed down five months before the ruling.
Yogananth Andiappan, yoga director at Anahata Yoga, an internationally accredited yoga centre specialising in teaching instructors, said a lack of training for the yoga teacher could result in injuries.
"(Injuries are) possible when instructors are not knowledgeable or experienced in yoga," he told AFP.
Instructors who attend Anahata's yoga centre must complete 200 hours of training and pass practical and theoretical exams before they are certified.