DOCTOR ON CALL ASK THE EXPERT I'm a middle-distance runner on my school's athletic team. Recently, I've been getting pain in my lower leg over the front and outer part of my shin. Should I be worried?

IT SOUNDS like you have shin splints. This is a general term used to describe shin pain from a number of different causes. It can develop in the muscles at the front and outer part of the shin. This is called an anterolateral shin splint. Pain in the muscles at the back and inner part of the shin is probably due to a posteromedial shin splint.

The usual cause of shin splints is repetitive stress to the lower leg. Runners, walkers and regular skiers are prone to developing anterolateral shin splints.

If you originally felt pain immediately after your heel struck the ground while running, but the pain now continues throughout each step, it is likely you have an anterolateral shin splint.

The next stage of the injury will lead to chronic shin pain with the front of the leg eventually becoming sore to touch.

Shin splints can also be due to micro-fractures associated with repetitive stress.

Runners and dancers are most at risk, with the pain increasing in severity the longer you exercise.

Foot bones called metatarsals are especially prone to stress fractures.

The main symptom is pain in the front part of the foot.

Stress fractures are more likely if you have a high foot arch or use running shoes with inadequate shock absorption.

Stress fractures are so fine that they may not be seen on a plain X-ray. A bone scan may show a "hot spot" at the site of the microfracture but the diagnosis is usually made by a doctor based on your symptoms and a clinical examination.

You cannot run with a stress fracture but you can substitute other exercises during recovery.

Shin splints can recur so if you start to feel this type of pain again, stop running and give yourself time to recover before getting back to regular exercise. Wear well-fitting supportive sport shoes and avoid running on uneven surfaces.

You should talk to your coach and explain what has been happening. He or she will probably suggest you stop running in the short term.

If there is any doubt about the diagnosis you should see either your own doctor or a sports-medicine specialist.

A sports physiotherapist will be able to advise you on how to protect your muscles from overuse and will give you an exercise programme aimed at strengthening certain muscles.

When you get back to running start off on a forgiving surface, such as grass, which will reduce the impact on your leg and foot.

Good luck with your recovery.

Dr Muiris Houston is Medical Correspondent of The Irish Times. Email your queries on sports medicine to sportsdoctor@irish-times.ie