DEAR DR. DONOHUE: My son’s coach informed the team that some players have contracted hand, foot and mouth disease and told them not to put their mouths on water bottles.

What is this disease? Is it transmitted by sharing water bottles? How is it treated? I have observed other teams sharing water bottles. Is this a safe practice? What alternative should be used? – S.C.

ANSWER: Hand, foot and mouth disease can strike anyone, but usually it picks on children 10 years old and younger. The cause is coxsackievirus, and the virus can be passed in a number of ways. Food and water contaminated with it are one way. Respiratory droplets are another.

Infection causes fever and a sore throat. The child (or adult) doesn’t want to swallow. The mouth and tongue break out with tiny blisters, as do the hands and feet – hence the name.

There is no special treatment other than making the sick person as comfortable as possible and keeping him or her hydrated.

Many viruses, bacteria and other germs can be spread through shared drinking containers. Coxsackievirus is one, but not the most common one. Outbreaks of infectious diseases have been traced to team-shared water or team-shared drinking containers. Water bottles can be easily contaminated. Not every germ-carrying person is sick, but the innocent recipient of the germ often becomes sick.

Team water should be in a safe container, like individual commercial bottles or a commercial jug whose sanitation is guaranteed. Players should drink from disposable cups. If they use water bottles, they each should have one of their own with their name on it, and they should not lend it to others.

The good old days of a water bucket and a communal ladle were not good old days. Those things should be a distant memory.

DEAR DR. DONOHUE: One of the worst things about getting older for me is the loss of balance I have sustained. I am quite unsteady. My doctor has gone over me a couple of times and says that, aside from age, there is nothing wrong with me. Can you suggest any exercise to help me? – T.R.

ANSWER: Loss of balance is a common complaint of older people. One reason for it is the muscle weakness that comes with age. The only way of overcoming that is through weight training. It sounds ridiculous to recommend weightlifting to older people, but they don’t have to hoist the heavy weights that power lifters and bodybuilders do. A modest amount of weight is all that’s needed to keep muscles from shrinking.

A little drill that helps balance and strengthens leg muscles is rising from a chair. A sturdy dining-room chair does fine. Without using your hands or arms, rise up from the chair and sit back down as many times in a row as possible and as many times during the day as you can.

A second balance exercise entails standing on one leg for five or 10 seconds and then alternating to the other leg. Keep doing so 10 or more times.

For any balance exercise, have a spotter on hand who can grab you if you are on the brink of teetering. A fall can be disastrous.

DEAR DR. DONOHUE: Is it best to practice right up to the time of a meet, or should you lay off for a couple of days before? I’m talking about swimming meets, but I guess you could make it apply to any athletic meet. – S.S.

ANSWER: It’s best to taper the intensity, frequency and duration of practice before a contest. You don’t have to stop completely, but you should back off some.

How much to taper is a question without an explicit answer. If you reduce practice intensity and time by two-thirds for one to two weeks before a big event, your performance doesn’t suffer. In swimming, it’s been shown to increase by 3 percent, a huge gain in a sport where seconds are the difference between first and last.

Reduced training gives muscles a chance to repair themselves and to store glycogen – muscle sugar that provides energy.

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.