I am sorry, I guess I got you all confused. so let me try and explain it better.

first, this test is a very crude and inacurate test, and is only meant to give you a general idea, in case you have non-specific symptoms and want to see if it may be related to respiratory muscle weakness.

it is not a breath holding test ( I am sorry but I am not familiar with the test on the link of MRs D, and can't comment on its utility or accuracy), but more assesment of the vital capacity. (although obviously much less accurate then a formal test).

what you do, is take in the deepest breath that you can and then count outloud as much as you can (basically while you exhale), without taking another breath in. this way you sort of check how much air you can get into your lungs, when you do a maximal effort of breathing in.

hope this is more clear.

alice