DEAR DR. DONOHUE: I read a terrible story in the paper that has me upset. A young boy was hit in the chest with a baseball and his heart stopped. If his mother, a nurse, and two other nurses in the stands hadn’t rushed to his aid, he would have died.

I have two young boys who play baseball, and I am concerned. What is their risk? Should they be wearing protective padding? How common is this? – D.K.

ANSWER: The boy who was struck in the chest with a thrown baseball suffered a condition called commotio cordis, a concussion of the heart. It’s a freak accident that happens rarely. A blow to the chest has to strike it directly over the heart. And the blow has to occur at a very precise moment in the heart cycle, a time measured in the thousandths of a second. When both position of the blow and the exact time interval coincide, the force imparted transforms the normal heartbeat into a heart rhythm called ventricular fibrillation (not atrial fibrillation). The heart stops beating. The heart muscles are not contracting. They’re ineffectively squirming (fibrillating). The heart pumps no blood. If a normal heartbeat isn’t promptly restored, death occurs. The boy’s mother and the two other nurses instituted cardiopulmonary resuscitation promptly and saved the child’s life.

Commotio cordis is a most uncommon cause of death in young athletes. It has happened in many sports – lacrosse, karate, baseball and even during innocent playing around in a backyard. One child died after being struck in the chest with a lightweight, hollow, plastic bat.

This is low on the list of causes of sudden death in young athletes. Most often, such tragedies happen to children with undiagnosed heart disease and the condition most frequently involved is cardiomyopathy.

Attaining zero-risk for childhood athletes is impossible. That sounds callous, but it is true. If we want to protect children from danger, we would never let them ride in a car. I don’t know if padding is the answer to this kind of tragedy. I would think coaches and game officials ought to be trained in CPR – cardiopulmonary resuscitation – a technique not difficult to learn.

DEAR DR. DONOHUE: What’s the scoop on drinking coffee before exercise? Does it increase a person’s stamina? How much do you have to drink? Doesn’t it make you urinate? I don’t drink coffee, but I will if it really works. Does it? – K.C.

ANSWER: Coffee has become a health food. All sorts of wonderful things are alleged to come from it. For athletes, one recent benefit has been shown to be a decrease in muscle pain resulting from exercise. Two and a half cups is the recommended amount.

The same amount, taken about one hour before competition, is supposed to increase endurance.

Caffeine does not increase urination. Many believe that it does, but proof exists that it does not. It doesn’t lead to dehydration, either, another popular belief.

DEAR DR. DONOHUE: I am 86, 6 feet tall and weigh 175 pounds. In 1998, I had seven bypasses. In 2006, I had a pacemaker installed. I work out six times a week. One day I do 500 sit-ups and half an hour on a recumbent bike. On the next day, I do 500 to 750 repetitions on more than 20 different weight machines and lift, in total, more than 50,000 pounds. Am I overdoing? – B.V.

ANSWER: Your regimen sounds excessive to me. You must speak to your doctor. Ordinarily, those with heart disease who are at advanced age are told to perform moderately intense aerobic exercise for 30 to 60 minutes five days a week. “Moderately intense” is brisk walking. Lifting weights is encouraged, but light weights are recommended. Your program is over the top.

DEAR DR. DONOHUE: Can a person damage his spine by running on a treadmill excessively? – Anon.

ANSWER: Excessive exercise can damage many parts of the body. Routine treadmill exercise should not hurt the spine. If a person notices back pain when running, he or she should stop and find out what the cause is. It might be the posture one assumes when running, or it might be a more serious condition.

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.