Asthma is almost totally a problem of obstruction while exhaling. This would cause wheezing while exhaling. Often a simple breathing test called spirometry is helpful in diagnosing asthma.
Wheezing while inhaling suggests an upper airway obstruction. This is commonly seen with vocal cord dysfunction (VCD). The vocal cords should be open while inhaling. VCD is a condition that causes the vocal cords to close together while inhaling. Testing needs to be done while you are having symptoms.
A definitive diagnosis of asthma would be a bronchial provocation study (methacholine challenge). Just because you hear wheezing does not mean that you have asthma. You may be sensitive to something in the environment or at your work but that does not mean you have asthma. It would be wise to see your physician to discuss some possible tests that may be performed to determine if you have reactive airway disease or asthma.
As for when you should hear wheezing. Asthma attacks occur when the airways become inflammed or the muscles surrounding the airway spasm for some reason. Generally, the wheezing would be heard on exhalation but can be heard on inspiration as well. Mostly, wheezing on inspiration can signal an obstruction in the airway. So again, there is no way to tell if you have asthma by just listening to you. Seek out the professional advice from a physician so you can have the proper tests run. Take care and good luck..
JCI, BS RRT
The advice above is great!
I've also been told that it's possible to have just exercise-induced asthma or exercise-induced bronchospasm EIA or EIB. This m-a-y not show up from a methacholine challenge test, so if you and your docs believe you may have this condition, you may need to have a test for EIA/EIB as well. Best of luck! Starion