PHOENIXVILLE, Pa. (WPVI) -- Shortness of breath during a workout may seem like just a sign of being out of shape.
However, it might actually be exercise-induced "asthma."
Caitlin Miller of Phoenixville, Pa., loves long-distance running - even the training -
"Being out by myself. That's like my time to be by myself and just think," says the 32-year-old Miller.
But last year, she developed trouble breathing.
"It felt like my lungs were underwater. I originally attributed it to like humidity," Miller recalls.
When it happened even briskly walking her dog, she began seeking medical answers.
Every test was negative, until Dr. Sean Duffy at the Temple Lung Center found that strenuous exercise narrowed her airways.
While it's often called asthma, it's actually a bronchospasm, or bronchoconstriction.
"The inhalation of a large amount of cool, dry air at one time, can actually essentially dehydrate the inner lining of your airways," says Dr. Duffy.
"Your nose is there to warm and humidify the air we take in. You lose that when you're taking big, deep breaths very quickly," he adds.
"People talk about shortness of breath, chest tightness and cough," he continues.
Air flow typically drops in the first 10-15 minutes of activity, then gradually improves, returning to normal in an hour.
It's most common in cardiovascular activities like running, rowing, cycling, cross-country skiing, or dancing.
People with seasonal allergies can develop it too.
Preventive treatments with the right medication mix keep those like Miller doing what they love.
"We'll give people an albuterol inhaler. Sometimes an inhaled steroid, with a long-acting bronchodilator.," he says, adding, "A lot of patients take a medication called montelukast (brand-name Singulair)."
Warming or humidifying the air one breathes also helps.
"Like a loosely fitting scarf around the neck or the mouth, a gaiter, a mask," he says.
Miller uses a neck warmer, even in warm weather.
That and medication got her through the Philadelphia half-marathon just fine.
"It does just give that extra warmth that keeps everything like flowing easily," she notes.
Miller says a journal of her breathing problems help in adjusting treatment.
And don't give up - find a doctor who listens to you, and will work with you to improve breathing while continuing the activities you love.