Q. I've been doing a lot of running lately, and seem to be suffering from what most people call shin splints. What exactly is this condition, what causes it, and how do you get rid of it?

A. Shin splints are leg pains usually caused by excessive use, expecially running on hard surfaces. Runners often get these after suddenly increasing how far they run.

Besides being caused by overuse, shin splints seem to be aggravated by using the leg muscles that point the foot down more than the muscles that bring the foot back up, which happens in running. This combination of stresses leads to inflammation and possibly tiny tears in the leg muscles and the tendons that attach these muscles to bone.

Strictly speaking, the pain of shin splints is felt along the lower, inner part of the leg above the ankle. But the term is also used to refer to any pain in the leg associated with overuse. The affected area is also tender, but it shouldn't be swollen or numb, and you shouldn't have any leg weakness.

Treatment starts with rest, to avoid further damage from an intensive running program. You can use ice initially, then moist heat, to the painful area, and aspirin or other anti-inflammatory medicine. Once things have quieted down, you can gradually resume your running program, preferably on softer surfaces. You should also work on equal muscle development of the leg extensor and flexor muscles that move your feet up and down.

Two conditions whose symptoms resemble shin splints are stress fractures and the compartment syndrome. Stress fractures are brought on by overuse and are usually visible on X-ray, although sometimes you may need to have a bone scan to see them. In any event, the lower part of the leg is not a common place for stress fractures to occur.

The compartment syndrome results when excessive use of the leg muscles causes them to swell within the tight confines of muscle compartments, which are bounded by tough fiber envelopes. This swelling cuts off precious blood supply and produces pain and sometimes numbness and leg weakness lasting for several hours after running. This condition is fairly uncommon.

I think it's wise to think of pain with running, or any exercise for that matter, as nature's way of telling you to slow down. If it persists in spite of taking good care of yourself, see your doctor to make sure you don't need further treatment and for advice on additional preventive measures.

Q. In 1955, I spent eight months in the hospital, one month of that in an iron lung in D.C. General and seven months learning to walk again at Providence Hospital. For 30 years I've enjoyed wonderful health, but suddenly I'm having breathing problems. I understand I'm not alone. Doctors are seeing many post-polio victims whose weakness is coming back. Could you address this problem and tell me where I can go for help?

A. You'rego, only to come down with new symptoms. This condition is re-Pains of go, only to come down with new symptoms. This condition is re- Pains of post-polio syndrome are worse in muscles that were not initially affected by polio. ferred to as the post-polio syndrome or post-polio progressive muscular atrophy (PPMA).

About 300,000 survivors of the polio epidemics of the 1940s and 1950s seem to be at risk for developing this syndrome, which is estimated to affect up to 25 percent of survivors after about a 30-year lag.

The syndrome appears to be more common in people who had more severe disease at first, and in those who came down with polio after the age of 10.

Symptoms of post-polio syndrome include extreme tiredness after only moderate activity, muscle pain and weakness, breathing problems, sleep difficulties and increased sensitivity to cold.

The muscle pains are actually worse in muscles that were not initially affected by polio, a disease that attacks nerves in the spinal cord and causes muscle weakness and wasting (atrophy). The pains seem to result from increased work that normal muscles have to do to make up for weakness in the muscles affected by polio.

Researchers aren't sure what brings about these new symptoms in polio survivors after such a long period. One theory is that post-polio syndrome results from a combination of the effects of polio and aging on nerves in the spinal cord. Another is that polio alone causes ongoing damage to nerves that continues later in life. Another theory suggests that post-polio syndrome is an immune disorder, the result of the body's defense system going awry and attacking various muscles.

Treatment starts with making sure that nothing else is causing the symptoms involved. If not, then the goal is to try to relieve the symptoms, because no cure as yet exists. Pain relievers and anti-inflammatory drugs are used to treat muscle aches. It's recommended that you rest as needed and avoid heavy exercise, although light exercise may help keep your good muscles in shape.

Mestinon, a drug that improves the signals between nerves and muscles, is being tested as a possible aid in combating the severe tiredness that some people with this condition suffer from.

In addition to the medical problems that post-polio patients have, the emotional effects can be just as devastating. Many people like yourself have fought hard against a dreaded affliction and overcome prior disabilities, only to be faced with another threat to their health. For help in dealing with this new problem, you can contact the Post-Polio League for Information and Outreach, 1089 Travis La., Gaithersburg, Md., 20879, 897-8180. They can provide information about post-polio clinics, research and support groups.