One of the most common concerns we hear about is the occurrence of shortness of breath with exercise.

It always raises the question, is my child simply winded from running so intensely, or does it indicate something is going in my child’s lungs that needs medical attention?

Normal breathing hard

Certainly everyone breathes harder when they run or exercise.   It all has to do with the very reason we breathe at all- to provide adequate oxygen to every cell in our body that needs oxygen.   Curiously, every living cell in the body requires oxygen, and with two exceptions, only gets it directly from blood carrying oxygen delivering to each cell.  Those two exceptions are the cells of our corneas and of our cartilage.  Cartilage lives on the very low oxygen content that diffuses from nearby tissues as it has no blood supply within.  And the corneal cells get their oxygen from air.  So for all other tissues, if they get oxygen, it’s from our blood, and every last molecule of oxygen comes from only one source, our lungs.

So, when we exercise, our muscles’ need for oxygen leaps upward, and so the blood must deliver more, a lot more, and soon.   There are two ways to deliver more oxygen to working muscles- one is to have the heart pump more blood each second to the muscle, and the  other is for the lung to pack more oxygen into the blood. The heart does its part by pumping a bigger gush of blood with each beat and by beating more often each minute.  This explains why after running our heart always goes faster and pounds harder.   Our lungs do their part by the same two techniques.  They blow more oxygen by our waiting blood by taking deeper breaths, and by breathing more breaths per minute.

And this is why everyone breathes harder after running.  We take deeper breaths and we breathe faster.   If we exercise to a degree that our muscles call for more oxygen than our lungs can deliver, we end up trying to breathe faster and deeper than we can.  This is the source of panting, huffing, puffing after very strenuous exercise.

Every parent will see their child huff and puff and pant after they run hard enough to create such demand.

This sort of trouble breathing goes away as soon as your child rests, and if you talk to  your child, you’ll find out that they feel winded, but air is flowing easily in and out of their chest.  They may be panting, but there is no struggle to get the air actually in and out, just feels like there isn’t enough air.

Exercise induced bronchospasm and asthma

So, every child who runs hard enough runs out of breath, but not everyone actually has their lung airways narrow and develop real troubles with the flow of their air.

Not everyone, but many, many.   About 1 in 20 children have asthma, and nearly all of them experience some asthma like symptoms when exercising, if their asthma is active.   But far more than that, about 1 in 4, and in some studies as many as half, of all children experience their airways narrowing when they exercise, this is exercise-induced bronchospasm, or EIB.

Why do our lungs’ airways get narrow when we exercise?  Why do they narrow at all?  What sense does it make to have the tubes that deliver air ever get narrow?  This is a question anyone with asthma or with a child with asthma would like to know the answer to.

It turns out that everyone’s airways (the tubes that deliver air to the little air sacs at the end of our lung channels) can narrow, everyone’s.   Everyone’s airways are made out of tissue that can swell, that can make mucus, and that can tighten with the grip of a muscle.  Everyone.  The reason appears related to the fact that for the very reason lungs can draw the world’s air deep into the tissue of the lung, the lung therefore must be able to protect itself from harmful items in that air.  Those could include items such as smoke from a fire, toxic chemicals, dangerous germs, extremely cold air.  A bad germ landing on one airway can cause that airway to swell and make pus and in response its surrounding muscles can go into spasm and seal off the rest of that part of the lung to that infection, a very protective act.  Or, you might walk into a space filled with smoke and blazing hot air, the lungs’ airways constrict and keep the smoke and burning air from destroying your entire lung, giving you a moment to get into safe air.

So this mechanism is in everyone.  Asthma is a situation in which these normal protective actions happen for no good reason, for too easy a  provocation, say breathing in some pollen, or catching a cold, or, exercising.

EIB happens in people without asthma because for a very large number of people, remember it’s as many as a quarter to half of humanity, simply breathing air deeply and rapidly activates this protective reflex, the muscles around a lot of our airways contract, and the airway narrows.

Whether by asthma or by EIB, what happens when the airway contracts?  It makes the flow of air much, much, much harder.  Once the airway gets good and narrow breathing, even with your mouth wide open, feels like you are breathing through lips tight around a tiny stray, it’s suddenly a lot of work to breathe, it feels like you are tugging hard to pull air in to your lungs.  Narrow airways are also very musical, making high-pitched squealing, violin-string sounding squeaks we call wheezing.

So, if you ask your child who is panting after soccer how they feel, and they say it is hard, it feels like they are struggling to pull air into their chest, that they hear wheezing, and it’s lots of work to blow air out too, it’s not simply being winded, it is EIB.

What to do with EIB?

If your child does not have asthma and their symptoms of EIB do not bother them and go away rapidly when they rest, there is no need to do anything but rest.

But if the EIB bothers them, a puff or two of a medication called albuterol sometime before the exercise via an inhaler can eliminate this trouble quite well.

BOTTOM LINES

1. Everyone’s lungs consist of myriad little tubes called airways that deliver air you breathe in to the little air sacs in your lung where oxygen gets delivered into your bloodstream.
2.   These airways are wrapped in spirals of muscle, that if contracted, narrow the airway.  All airways also can swell and make mucus which also narrows the airway.
3. Everyone’s airways can narrow, but most people’s do not without some pretty dramatic provocation, like smoke from a fire.
4. Everyone breathes harder and faster when they exercise and everyone can outpace their ability to keep up with the demand for oxygen, leading to heavy breathing, panting, huffing and puffing.  But this experience causes no trouble with air flowing in and out of the chest and does not cause wheezing.
5. A surprising number of children (up to 1/4 to 1/2) experience their airway muscles contracting with exercise, causing narrowing of the airway, shortness of breath, a feeling of struggling to breathe, and even wheezing.  This is exercise-induced bronchospasm (or EIB).
6. EIB if mild and not bothering your child, can be treated simply with rest, but if it gets to be a problem, call us to discuss possible therapies.
7. Asthma is a condition in which a person’s normal trigger to have their airways narrow with swelling, mucus production, and also airway muscle spasm.  This requires more therapy than simple EIB.

I wanted to thank the Ms. Lucy Li, a student at the Case Western Reserve School of Medicine for her very thorough research for this post while she was observing our work at Advanced Pediatrics.

To your health,
Dr. Arthur Lavin