THE stress of taking a ''personal development'' course now popular in Hong Kong could cause medical and psychological problems including hyperventilation, palpitations, chest pains, depression and anxiety attacks, a doctor has warned. An expatriate doctor who took a course earlier this month recalled how one participant was unable to stand because he was hyperventilating. Later the same man's fingers and thumb locked together in a claw-like position because of a spasm caused by severe hyperventilation. The doctor, a general practitioner, added although sessions could last for up to 14 hours there was only one meal period, and up to four hours between short breaks. With students actively discouraged from going to the toilet during sessions, many people drank only sparingly, leading to possible dehydration, she said. The effects of hyperventilation could cause heart palpitations, dizziness, faintness, chest pains, numbness and tingling sensations, she warned. The doctor, who asked not be named, signed up for an advanced course with Asia Works after taking an introductory basic course. Nearly 50 people attended the second-stage course held in Admiralty. Chris Gentry, who was formerly with another personal development course, Life Dynamics, led the training. Earlier this month the Sunday Morning Post disclosed how Robert White, who founded Life Dynamics, accused Mr Gentry of denigrating his former colleagues and poaching staff and students to Asia Works - charges Mr Gentry denied. Contacted about the events at the Queensway exhibition hall, Mr Gentry refused to comment on the allegations, only saying: ''I don't want to talk about this; this is really tough.'' The hyperventilation incident happened during a four-hour session known as ''the lifeboat'' in which people are asked to imagine they were on a sinking ship. They had 30 seconds to convince the other participants they should be allowed to ''live'' and get one of the few places in the lifeboat. ''We were all lying on the floor and were told to jump up. This Chinese man could not because his legs were tingling with a pins and needles sensation - a classic symptom of hyperventilation,'' the doctor said. ''Chris Gentry told him he had too much oxygen in his blood. That is not a proper explanation. ''When you hyperventilate as a result of anxiety, you blow off all your carbon dioxide and this is what causes pins and needles,'' the doctor said. ''They should have given the man a paper bag to breathe into immediately. ''Some people helped the guy up into a chair and tried to keep him upright - but Chris Gentry just shouted at them [to] '. . . leave him alone'. ''Later I saw the finger tips of the student's right hand were forced together because of a spasm known as tetany,'' added the doctor, who left the second of three Asia Works programmes after two sessions. Another student asked to be excused periodically because she suffered dehydration and was advised by her doctor to drink fluids regularly. Asia Works staff tried to prevent her from going, saying the entire course would have to stop while she went to the bathroom. ''It is outrageous; no one should be able to stop you having a drink,'' the doctor said. ''The staff might have had first aid training, but judging from the way Chris Gentry reacted to the case of hyperventilation, they do not seem to have remembered much of it.''