Lung function test isnt an indicator to wether you have asthma or not. Asthma diagnosis is done mainly by history of symptons. You could have normal lung function at rest and still have exercised induced asthma. Asthma is characterised by the lung tissue reacting abnormally to exercise or a trigger like a pollen etc. Lung function is used to gauge the extent of lung disease which erodes lung function such as COPD. It can be used to gauge asthma severity during an attack or during exercise.
So taking a form to say you have a peak flow of 600+ (after youve blown into a tube) doesnt mean you are asthma free or even have asthma. If you have any history of asthma and have taken medication for it then the forces are cautious. Not just because of the extent of physical exercise but also because most forces PT is done in far from healthy enviroments such as S10's and shitty weather etc.
The 4 year rule is mainly for people growing out of their teens and childhood asthma, even though there is now evidence to suggest that asthma never goes away, but during your twenties your lungs cope better as they have matured. Sadly in your thirties or later asthma can become a problem again as your lungs age.
In REMF units asthma if discovered post training and trade training can be tolerated, but in commando or airborne units it usually isnt depending on your role. However asthma in any basic training isnt tolerated.
If you have been treated with steroids for a chest condition this doesnt mean you have asthma either. Treatments for asthma can involve steroids either inhaled at low dose or orally at higher doses. Alongside a short acting or long acting beta two drug such as ventolin. Steroids are more preventative in treating the lung tissue and preventing inflammation whilst B2's are rescue therapy that open inflammed airways during an attack, now though treatments like seretide and symbicort which are combinations of both types of drugs attack the disease in regular sufferers from both angles. Asthma isnt the only disease that cause lung tissue to inflame and some infections do this also hence steroids as treatment. Unfortunately if you have a history of asthma and then get treated for a chest infection with a steroid the powers that be dont really want to get ot the bottom of it and class it as asthma and your binned.
There are members of the forces who have asthma but this is usually discovered after a few years service and the money spent to train these people is a huge consideration on wether they are kept or not. They usually get transferred to a desk or remf job. But if your in training or going through the application process then not alot of cash has been spent and so your binned. The forces also have a duty of care to you, your oppos and unit effectiveness (and medic workload

) so bottom line is if the doc thinks you have asthma and its going to cause problems (Which is the usually scenerio) then your binned.
If anyone is reading this and is applying and has asthma try and see it form not only a PT point of view in the gym, but also the forces point of view in that the gym is a means to an end and controlled. If you were in northern norway miles from anyone and your unit relied on you to help it complete its task and you started to wheeze, then the whole mission is farked. You or an oppo could even die. So they wont take the risk when a healthy lad next inline wont cause such problems.
and Dlink to take a form to a CO you have to be a serving serviceman or woman in a unit and therefore have a commanding officer. You are not serving so therefore dont have a CO. Plus your advice isnt right and Brain was merely suggesting he would value advice from someone other than a walking plank who spends his time wondering where bullets from a jet go after they have been fired!