How do you do Marcante-Odaglia? I'm not finding any good resources online that do a good job of clearly demonstrating how to execute this technique?
Marcante-Odaglia was the "secret" method employed during WW2 by Italian Gamma men (and one woman).
The method was formalized after the end of war by Duilio Marcante, one of pioneers of formalised scuba training, which possibly was introduced to him by Luigi Ferraro, the most successful Gamma man during the war, and the first scuba instructor for recreational diving courses, started by Ferraro in 1949.
For understanding the physiology of this equalization method Duilio Marcante asked for help to one of his friends and diving pioneer, prof. Odaglia, one of the first specialists in hyperbaric medicine.
They published a paper around 1952 describing the method (in Italian).
Some years later, when this method was largely employed here by the community of recreational scuba divers who were using the ARO CC pure-oxygen rebreathers, an alternative method emerged in the community of spearfish free divers, the Frenzel method, also developed during WW2 for aircraft pilots.
The two methods share some common points:
1) pinch your nose
2) create internal pressure without using lungs.
But the two methods differ about how this pressure is created.
In Frenzel the pressure comes by the tongue, which is arched up, compressing the soft tissue separating the mouth from the nose. Hence Frenzel is done usually with the mouth closed and without breathing. The three main valves of our airways (lips, soft palate and epiglottis) are held closed.
Instead people using the ARO did not like to remove the mouthpiece for practicing the pure Frenzel, they preferred to keep the mouth and the epiglottis open, and being able to continue the very slow respiratory cycle required by the ARO without interruption.
So in the Marcante-Odaglia method the tongue is not used. The tongue is a powerful muscle: without it, the pressure generated is much smaller than with pure Frenzel (or Valsalva).
The only muscle available for the Marcante-Odaglia is the palatine muscle, the one which raises the soft palate and closes the passage of air between mouth and nose.
Almost all people can control voluntarily this muscle: for example when you blow through a pipe making bubbles in the water in a glass, or when you fill a balloon with your mouth.
So, learning to shut close your soft palate is easy. The problem is that doing just this, with the nostrils closed, causes just a modest overpressure inside the naval cavity, which could not be enough for opening the tubes, if they are congested.
Hence Marcante Odaglia is very easy to teach and practice, but unfortunately is not as powerful and effective as Valsalva or Frenzel. The latter, indeed, is much more complex, as it requires to coordinate the motion of the tongue against the soft palate in a quite unnatural way, which can cause vomit to some people, and generally is not so easy to teach and to learn.
Hence I consider the pure Frenzel, and the even more complex (but more powerful) Frenzel-Fattah methods as advanced methods which are only advisable for deep free divers or competitive spearfish hunters.
For us, normal rec divers, the Marcante-Odaglia is a good option, if our tubes can be opened easily. When they can't, you have to resort to good old Valsalva (or to BTV if you are lucky, having voluntary control of the small muscles which act directly on the tubes, with no involvment of tongue, glottis, jaw or soft palate).
Back to Marcante-Odaglia: despite the advantages of this method, it started to fade out also here in Italy, after Duilio Marcante passed away, in 1985. Previously almost all Italian diving instructors were trained by him in the Federal Didactical Center in Nervi (near Genoa).
I was there twice, in 1978 and 1982, so I learned this method (and its history) directly from him.
Instructors trained elsewhere did not learn this method, and of course they did not teach it to their students. Furthermore, many people got the erroneous understanding that Marcante-Odaglia and Frenzel are basically the same.
So I can understand how nowadays it is difficult to have proper information about the Marcante-Odaglia method. It is clearly described in his books, which indeed were never translated.
Hence I fear that this method will progressively disappear. I am probably one of the very last instructors who were so lucky to be trained directly by Duilio Marcante (and so unlucky to having been a patient of prof. Odaglia, but this is another story).
