They were persuaded by doctors at the Centre for Impotence and Fertility in Rome that the only valid way to test the efficacy of the treatment was by applying a kilogram weight - equivalent to a large bag of sugar - to the end of their penises to assess their rigidity.
If the weight did not buckle the penis, that would be proof that the treatment worked.
In all, 123 men agreed to participate in the study, ranging in age from 33 to a remarkable 77. The drug, alprostadil, was inserted into the urethra (the opening of the penis) and the men were given what doctors call "visual erotic stimulation" - pictures of undressed women to you and me.
First, the hardness of the penis was assessed using an electronic rigidometer called a Rigicompt which measured the pressure. Once this rose above 75mm of mercury it was judged to be fully rigid.
Next the men were subjected to the "penile buckling test". If they could carry the kilogram weight - no hands allowed - they passed.
The test was carried out using a virility meter. The device is applied to the top of the glans of the penis and presses downward, recording the pressure in grams.
Dr Ermanno Greco, who conducted the study with his colleague Dr Paolo Polonio-Balbi, said: "It is a machine which expresses your virility. You can see exactly what your power is. It is not such a severe test."
An erection capable of lifting a weight of 750 grams - three-quarters of a bag of sugar - is good enough for intercourse, though it is not fully rigid, Dr Greco said. Men who can support a kilogram weight from the end of the penises are at peak virility and push the machine off the scale.
The results of the study, reported in the Lancet, showed that the drug improved the blood flow in all patients, increasing the size of the penis and more than doubling it in some. Unfortunately, "not many had a real and lasting hardness," Drs Greco and Polonio-Balbi say.
There was complete rigidity in 11 men and a full but not lasting erection in 16 that subsided in one to two minutes.
Five patients were sufficiently impressed to try the drug at home and two "got good results", the doctors say. The other 118 returned to using the injections direct into the penis that most of them had previously relied upon.
The performance of even the most successful Italian volunteers pales beside the exploits of the sadhus of Nepal. In Chomolungma Sings The Blues, an account of travels around Mount Everest by the mountaineer Ed Douglas, he describes meeting a sadhu who offers to lift a rock with his penis - for a price. How much does the rock weigh? Over 80 kilos. "It is a hard life," says the sadhu.