LONG strips of white silk hang from a wall in qigong master Lim Khiam Khoon's consultation room in the Qian Jin Zhui Chinese Physician Recuperate Centre along Changi Road.

Each strip has a safety pin and a numbered tag. On the floor next to the wall are scores of neatly arranged weights, ranging from 2kg to 20kg.

The silk strips belong to about 60 men, ranging in age from 38 to 75, who are Mr Lim's students in a most intriguing form of exercise: Iron Crotch Qigong.

The tie tai gong, supposedly developed by a Shaolin monk called Seng Feng during the Tang Dynasty, requires practitioners to tie one end of a strip of silk around the base of their genitals and the other end to a stack of weights. They then lift the weights with their family jewels before swinging them like a pendulum.

Mr Lim, 61, claims that doing this not only strengthens a man's genitals, but will also give other parts of the anatomy such as the spine, lungs, liver, gall bladder and bladder a vigorous workout.

He had learnt it from his late qigong master.

'Exercising one's sexual organs improves blood circulation, energises the body and develops a person's internal strength as well,' says Mr Lim, who has been teaching qigong for more than three decades and practising tie tai gong for two.

Western doctors interviewed by The Straits Times say there is no scientific basis to his claims and caution that the practice can cause great damage to the penis.

One doctor, who declined to be named, says: 'The male sexual organ is a mass of muscles and doing this can cause muscle strain and sprain.

'The strain can also strangulate the blood supply and cause gangrene or tissue death.'

Urologist Peter Lim agrees: 'You wouldn't want to undergo surgical repair or emergency reconstruction if the penis fractures! Blood loss can be significant and life threatening too!'

The qigong master, however, says each man is carefully assessed before he begins training and adds that not one of his students has suffered injury. They start with very light weights before graduating to heavier ones.

Mr Lim, who is also a Chinese herbalist and acupuncturist, charges $3,000 for the first 100 sessions and $120 each month thereafter.

Many of his students train every day.

On hand to demonstrate the skill to The Straits Times were three men coached by him: former journalists M.K. Leang, 75, and Hoh Beng San, 71, and pub owner Mike Ng, 38.

The ritual begins with a genital massage by Mr Lim to loosen muscles and warm them up.

Mr Leang and Mr Ng then manage 20kg and 30kg weights effortlessly while the very sprightly Mr Hoh confounds as he swings 50kg 25 times with great vigour.

The routine ends with Mr Lim hitting various 'vital acupuncture points' on the men's bodies with a bundle of thin iron rods wrapped in a piece of denim cloth. This, he claims, improves blood circulation.

All three look robust and claim that practising the Iron Crotch Qigong has improved their overall health and virility.

'No need for Viagra. I have no problems in that department,' quips Mr Hoh, a grandfather of three.

He started learning the skill three years ago just as he was about to undergo an operation for a badly misaligned spine.

'My back was killing me and I had already tried all sorts of treatments. Doctors told me I might end up in a wheelchair after the operation,' he said.

He knew about the qigong master, having written about him during his days as a journalist.

'I was very sceptical but I told myself I had nothing to lose so I gave this a try,' he recalls.

His back pain disappeared after six months and he claims he can now run up and down stairs with alacrity.

Mr Ng, meanwhile, shows a scar on his back.

'I had three slipped disc operations before I took this up seven years ago. I've been fine since,' says the father of four girls.

Mr Lim, who is married and has a son in his 20s, is well aware of the scepticism of Western doctors.

He says: 'They look at this from the perspective of Western medicine. But this is qigong, it's different.'

However, he strongly advises people against doing this on their own as they can hurt themselves.

'I supervise all my students and make sure they do it correctly. We know what we're doing.'

This article was first published in The Straits Times on May 3, 2008.