DEAR DR. DONOHUE: I have 12-year-old twin boys, and both play hockey. They’re about equal as far as hockey skills go, but one has a hard time keeping up with his teammates. After skating for some time, he’ll start coughing, and he looks like he’s struggling to breathe. Sometimes this happens after he’s been skating and is sitting on the bench with the rest of his line. I remember you writing something about exercise and asthma, and wonder if this might be his problem. Would you repeat what you said? I didn’t save the article. – W.O.

ANSWER: Exercise-induced asthma is a real thing that affects many athletes. It often goes unrecognized for what it is. With asthma, airways narrow and mucus production goes into high gear. The combination makes it hard to get air into and out of the lungs. Coughing, wheezing or shortness of breath – any one or all three – is a sign of asthma.

During exercise, athletes are generally forced to breathe through their mouths to get enough air. The air in a hockey rink is usually cold and dry. The cold, dry air cools and dehydrates the airways. The can cause a release of body chemicals that constricts the airways and makes filling and emptying the lungs difficult. The reaction often happens after strenuous efforts. You mention your boy can get into trouble when he’s sitting on the bench after playing. The reason is that his airways are beginning to warm, and that increases the production and release of airway-constricting chemicals.

Have the boy checked. A doctor can measure his lung function after he has exercised and see if it drops. He or she can witness the kind of reaction the boy has, and that’s important evidence in establishing the diagnosis. If the boy turns out to have exercise-induced asthma, medication before playing can usually prevent attacks. Olympic gold medalists have suffered from this condition.

The asthma booklet describes ordinary asthma in detail. Readers who would like a copy can obtain one by writing to: Dr. Donohue – No. 602, Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.75 U.S./$6 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: I regularly donate blood, but my most recent visit found an unsatisfactory hemoglobin level, so I was turned down. I am an avid cyclist averaging 100 to 120 miles per week of hard road biking. I rarely eat red meat, and I take daily aspirin and a daily vitamin that has no iron. I am 64.

Would my exercise expand my blood volume and give a false positive low hemoglobin? – H.F.

ANSWER: For readers: Hemoglobin is the stuff inside red blood cells that holds onto oxygen as the red blood cell passes through the lungs. It serves as a surrogate marker for a person’s red blood cell count.

Yes, you could have what’s called sports anemia. Hard exercise causes the body to conserve salt and water. The water remains in the circulation. It is beneficial for an athlete to have this extra water. It makes blood less viscous and enhances circulation. It also dilutes hemoglobin so it looks like a person has an anemia. That person is not anemic. He or she has the right number of red blood cells.

The explanation is plausible. All the same, you have to be checked. You could have other problems, like blood loss from your daily aspirin. Your doctor can distinguish between sports anemia and blood-loss anemia without much trouble.

DEAR DR. DONOHUE: Please clear an issue for me. How many sets are best for gaining muscle strength? Is one enough? I hear that it is from a person who considers himself an authority – on everything. – W.W.

ANSWER: A set is a number of consecutive lifts.

There’s much controversy about the number of sets needed to gain strength. Some do say one set of eight to 12 consecutive lifts is enough. More say that three sets is the better way to build strong muscles. I go along with them. Each set should be followed by one to three minutes of rest.

DEAR DR. DONOHUE: My daughter has trigeminal neuralgia. She has sharp, stabbing pains on one side of her face. She took anti-convulsant medicines (carbamazepine, etc.), which didn’t help. She is now on baclofen. They say a small blood vessel is pressing against the nerve and that a doctor can cure it with surgery, but she was advised not to have it done. She is only 47. I am concerned about the side effects of her medicines. What do you say? – J.S.

ANSWER: The horrific pain of trigeminal neuralgia, like an ice pick plunged into the face, lasts from a few seconds to two minutes. Although brief, the pain is so severe that people live in constant dread of another attack. Attacks can recur many times during the day. Innocuous things like shaving, washing the face, chewing or a light breeze blowing on the face can provoke one.

The cause is believed to be compression of this facial nerve by an artery looping around it and compressing it from its pulsations.

Anti-seizure medicines are often successful in suppressing the pain, as is the medicine your daughter is currently taking. People have been on these medicines for years without suffering intolerable side effects. However, your daughter has other options. One is radiation to the nerve, called gamma knife surgery. No knife is involved, but the gamma radiation works like one, destroying the nerve and eliminating the pain. The surgery you mention is curative more than 70 percent of the time. I don’t know why your daughter has been advised not to investigate it. She can talk to local neurosurgeons, the doctors who perform the operation, which consists of placing a spongelike pad between the nerve and the artery to dampen pressure on the nerve.

Your daughter might not be aware of all her options. Tell her to contact the Trigeminal Neuralgia Association at www.fpa-support.org for comprehensive information and direction.

Canadians can reach the Trigeminal Neuralgia Association of Canada at www.tnac.org.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com