It strikes when you walk — a distinct pain or cramping in your calf. You stop for a few minutes, and the pain goes away. You continue on, and the pain returns. You may just chalk it up to getting a bit older and decide it's time to put away your walking shoes for good.

Instead, head to your doctor's office. Leg pain when exercising isn't a normal part of aging. Rather, it may indicate that you have a potentially serious circulation problem that needs medical attention — peripheral arterial disease.

Treatment may help you return to a more active lifestyle and prevent potentially debilitating or deadly health problems, including amputation, heart attack or stroke. In fact, walking may become a key component of your treatment program.

One of the classic indications of peripheral arterial disease is often pain in the muscles of the legs — a cluster of symptoms called intermittent claudication. In peripheral arterial disease, also called occlusive arterial disease or peripheral vascular disease, the arteries that supply blood to the legs are narrowed, typically by atherosclerosis.

Although atherosclerosis is more commonly thought of as a heart disease, it can affect arteries anywhere in the body, including those in the legs and brain. Healthy arteries are strong, flexible and elastic, and the inner walls are smooth, allowing blood to flow freely through them to nourish tissues and organs.

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Atherosclerotic arteries, in contrast, become hardened and narrow as they get clogged with clumps of fats, cholesterol and other material, called atherosclerotic plaques. Those plaques act as barriers that impair blood flow through the arteries to tissues and organs (ischemia).

When this happens in the arteries supplying the heart (coronary arteries), it can cause chest pain (angina) or a heart attack. When it occurs in the neck or brain, it can cause a stroke. And when it occurs in the arteries to the legs, it can cause angina-like pain, cramping or heaviness in the leg muscles, known as intermittent claudication. You may also develop similar discomfort when using your arms.

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Intermittent claudication In peripheral arterial disease, the arteries that supply blood to the ... << ENLARGE

The pain of intermittent claudication often has distinctive features. For one thing, it's most often triggered by exercise, such as walking. That's because your muscles need more oxygen when they're working. But the narrowed arteries prevent sufficient oxygen-carrying blood from reaching them. The need for oxygen outweighs the supply, causing pain. Depending on the location of the arterial obstruction, you may have pain in the buttocks, thighs, calves or feet.

Another distinctive feature: The pain is intermittent. That is, it begins shortly after you start exercising and oxygen need rises, and it subsides when you stop exercising and oxygen need drops. The pain often gets worse when you demand more of your muscles, say climbing stairs, dancing or walking faster. Other things that can induce the pain of claudication include cold temperatures or medications, such as beta blockers, that reduce blood flow or cause your blood vessels to constrict.

If the obstructions in your arteries are severe enough, you may feel pain even when you're at rest. Your toes may be pale or have a bluish tinge. Your feet may feel cold to the touch. You may develop ulcerations on your lower legs, ankles, feet or toes. Though rare, the most advanced cases can lead to gangrene and require amputation.

Peripheral arterial disease and the associated pain can impair the quality of your life, if left untreated. It may limit your ability to participate in social and leisure activities, to work, and, of course, to exercise. Despite that, it often goes undiagnosed because many people consider the pain an unwelcome but inevitable consequence of aging and don't consult their doctors. But it doesn't have to be that way.

How do you know if the pain in your legs is intermittent claudication and not another condition, such as joint or muscle problems? Your doctor can make a diagnosis based on your symptoms — that stop-and-go pain with exercise is a telltale indication — along with a medical history, physical exam and appropriate tests.

Decreased pulsations in the arteries in your feet are also a common sign of peripheral arterial disease. Your doctor can check the blood pressure in your ankles and compare it to the pressure in your arms. That measurement, called the ankle-brachial index, can help determine the severity of your condition. In addition, Doppler ultrasound can measure blood flow through the arteries, while magnetic resonance imaging and arteriography can identify obstructions. Not all of these procedures may be necessary to make an accurate diagnosis, though.

Treatment of peripheral arterial disease is designed to stop it from progressing and to relieve your symptoms. Like the blockages that occur in coronary arteries, the plaques that accumulate in the arteries of your legs are often the result of unhealthy lifestyle habits. Treatment can also reduce atherosclerosis in other arteries in your body.

That means one of the first orders of treatment is to change any high-risk behaviors. Among the things you can do:

• Quit smoking. Smoking is the most significant risk factor for the development and worsening of peripheral arterial disease. Smoking increases the chance that you'll eventually require an amputation or even die of the disease.
• Exercise. If exercise makes your legs hurt, how can it be helpful? In fact, exercise is a key component of treating peripheral arterial disease and intermittent claudication. Exercise helps condition your muscles so that they use oxygen more efficiently. It can also increase development of collateral blood vessels — new blood vessels that form a natural bypass around obstructions, allowing more blood to reach the extremities. Your health care team can help develop a supervised exercise program that will enable you to gradually increase the distance you're able to walk without pain and increase your overall mobility.
• Eat a balanced diet. Follow a meal plan that includes a variety of low-fat foods, emphasizing fruits, vegetables, grains and legumes. Combined with exercise, a healthy diet can also help control your blood pressure and cholesterol, both of which can contribute to atherosclerosis.

If conservative treatment through lifestyle modification isn't sufficient to ease claudication or prevent the disease from progressing, you may have other treatment options. Your doctor may suggest medication that improves circulation by lowering how well platelets stick together, opening clogged arteries, and reducing your blood fats, such as cholesterol. Severe cases may require angioplasty, a procedure in which the diseased artery is widened with a balloon catheter and sometimes propped open with a scaffold-like stent — similar to angioplasty of coronary arteries. Surgery to remove or bypass obstructions may also be an option. And if you have obesity, diabetes or high blood pressure, those conditions must be treated, as well.

It may be difficult to make changes in your lifestyle, especially if you don't see immediate benefits or if exercising initially causes pain. But left untreated, you risk losing a limb or even your life. Effective treatment, on the other hand, can help you resume your normal activities and enjoy life more.