DEAR DR. DONOHUE: My small town is sponsoring a 10 K race, and I am in charge. Others are helping me, and we met this past week. A heated argument developed between two of our town’s best runners. One said we need to have water stations at every mile and we should tell the runners to drink even if they don’t feel thirsty. The other said we would kill them with too much water. He says we should provide salt. Who’s right? – C.F.

ANSWER: Both are partially right. In the recent past, the recommendation for long-distance running was to drink as much water as possible as often as possible. That, however, can bring on hyponatremia, a fall in the body’s sodium level. That can lead to lightheadedness and severe headaches. If the sodium level drops farther, seizures can occur. It can result in death. That hasn’t happened often.

Such troubles usually occur in marathon runs or runs that last four or more hours. You should not face hyponatremia in a 10 K (6 mile) run.

If you want to play it safe, space water stations every 1.5 miles and not every mile. Tell the runners to be liberal in their use of salt at meals in the days before and the day of the race. Providing a pre-run snack of a salty food like pretzels an hour or so before the race is a bit of insurance against hyponatremia.

If you want to play it really safe, then don’t give plain water at water stations. Stock up with commercial sports drinks that have sodium in them. Or you can make a sports drink of you own. Add 1 tablespoon of sugar and 1 tablespoon of orange juice containing 1/8 teaspoon of salt to 7.5 ounces of cold water. That gives the runners fluid and sodium. Or you can dilute a soft drink by adding to it twice its volume in water and putting 1/8 teaspoon of salt in every quart of the diluted drink.

DEAR DR. DONOHUE: I hadn’t played any tennis since last fall. Three weeks ago I started and have played daily since. My elbow hurts. I can hardly pick up a quart of milk without terrible pain. I guess this is tennis elbow.

What should I do for it, and what can I do to keep it from coming back? – R.R.

ANSWER: Stand and let your right arm drop down so the elbow is straight and the hand is at thigh level with the palm facing forward. With your left hand, feel for two small, bony projections at the sides of the elbow. The one on the side of the arm close to the body is the medial epicondyle, and the opposite one is the lateral epicondyle. Pain at the site of the lateral epicondyle is tennis elbow.

The lateral epicondyle is the site of attachment of the forearm muscles, the ones on the hairy side of the forearm. Overuse of those muscles stresses and disrupts their attachment to the epicondyle, and that produces the pain you have.

Rest is a must. Rest doesn’t mean total arm immobilization. It means not doing anything that causes elbow pain. In the first few days of tennis elbow, icing the site helps reduce pain. You’re past that stage. Start using heat on the elbow for 15 minutes three times a day. Anti-inflammatory drugs – Aleve, Advil, Naprosyn, aspirin, etc. – can dull the pain and curtail any inflammation. If these measures don’t take care of things, the doctor can inject some cortisone into the painful area.

To prevent a recurrence, resume tennis gradually. Before playing, apply heat to the elbow, and after playing, apply ice. A forearm brace, available in all sports stores, is a worthwhile investment. When you are pain-free, exercise your forearm muscles. While sitting, rest your arms on your thighs, palms upward, and with both hands grab a dumbbell. Bend the hands upward 10 times, then reverse your grip and repeat the same motion.

DEAR DR. DONOHUE: My vision got a bit blurry, and I thought I needed a change in glasses. I went to an eye doctor, who told me I had keratoconus. I am now wearing contact lenses. Is this a common eye problem? I have never heard of it. Would you please provide a little information? – T.U.

ANSWER: It’s not common, but it’s not uncommon either. It’s somewhere in between.

The cornea is the clear but tough, plasticlike covering of the central part of the eye. You can see the pupil through the cornea. It’s the eye’s equivalent of a window.

With keratoconus, the cornea thins and protrudes. The cornea becomes cone-shaped. That’s where the “conus” of keratoconus comes from. “Kerato” is borrowed from Greek, and it stands for the tough tissue of the cornea.

Because the cornea is misshapen, vision blurs, and this usually starts in the late teens or early 20s.

The process can progress very slowly. In the early stages, glasses can correct distorted vision. Special contact lenses not only correct vision but seem to slow progression of keratoconus.

As long as glasses or contact lenses permit good vision, that’s about all the treatment that is needed. If the process reaches a point where lenses cannot restore good vision, corneal transplants can. These transplants are among the safest and most successful of any transplant.

DEAR DR. DONOHUE: I have heartburn really bad, and I take Pepcid for it. It doesn’t do much good for me, so my doctor wants me to take a different medicine – Prilosec. How does this differ from Pepcid? Aren’t all antacids the same? – M.J.

ANSWER: Neither Pepcid nor Prilosec is an antacid.

Pepcid is a histamine antagonist. Histamine is a body chemical, one of whose functions is to promote the production of stomach acid. Pepcid and its cousins don’t allow histamine to land on the stomach’s acid-producing cells. The amount of stomach acid decreases, as does heartburn.

Prilosec works in a different way. It turns off the production of stomach acid in a manner similar to the way you would turn off a faucet that spouts water. Drugs in this category drastically reduce acid production.

Neither of these medicines neutralizes acid as antacid medicines do.

It makes all the sense in the world to switch to a different medicine when one does not do the job.

Many people suffer from heartburn, but few understand what’s going on or how the condition is treated.