You notice pain in your calf after walking for a while, and it goes away as soon as you stop. It always comes back at roughly the same distance. This very characteristic pattern has a name: intermittent claudication, and it's usually the first sign that the arteries in your legs aren't carrying all the blood they need.
What intermittent claudication is
Intermittent claudication is muscle pain in the legs that appears on walking and goes away with rest. It mainly affects the calf —the classic calf pain when walking— although it can also be felt in the thigh or buttock. It's the most typical symptom of peripheral arterial disease.
It's called "intermittent" because the pain comes and goes: it appears with exertion and eases with rest. That's why many people stop discreetly in front of a shop window to let it pass, a gesture so common that the condition is popularly known as shop-window syndrome.
Why it happens
When you walk, your leg muscles need more blood and more oxygen. If an artery is narrowed, it can't increase the flow enough. The muscle works with too little oxygen and signals this with pain. When you stop, demand drops, enough blood arrives, and the pain eases.
This narrowing is almost always due to atherosclerosis: the build-up of cholesterol, fat and calcium plaques on the artery wall. It's the same disease that affects the arteries of the heart. That's why having claudication is also a warning to keep an eye on overall cardiovascular health.
The factors that most favour it are smoking, diabetes, high blood pressure and high cholesterol. Smoking is by far the most decisive.
Claudication isn’t just a leg problem: it’s the visible sign that the arteries are diseased, probably systemically. Treating it in time improves mobility and, above all, protects the heart and brain.
"Shop-window syndrome" and its stages
Peripheral arterial disease is classified into stages according to how intense the symptoms are. The most widely used is the Fontaine classification, which helps to understand where each person stands.
| Stage | What is felt | What it means |
|---|---|---|
| I | No symptoms | There is narrowing, but blood supply is still sufficient. |
| II | Intermittent claudication | Pain on walking that eases on stopping. The leg receives enough blood at rest, but not during exertion. |
| III | Pain at rest | Pain even when sitting or lying down, often at night. Blood supply is insufficient at all times. |
| IV | Wounds or gangrene | Ulcers that won’t heal or necrotic tissue appear. This is the most advanced stage. |
Intermittent claudication sits at stage II. It's the phase where the most can be done to slow the disease down, so the pain shouldn't be dismissed as simply due to age.
Warning signs: when it's urgent
The progression from claudication to the severe stages (III and IV) is known as critical limb ischaemia. In that situation the leg is at risk and assessment shouldn't be delayed. Watch out for these signs:
- Pain at rest, especially in the foot and at night, which improves when the leg is hung outside the bed.
- Wounds or ulcers on the toes or foot that won't heal.
- A cold, pale or bluish foot, or areas of darkened skin.
- Sudden loss of strength, coldness and paleness of sudden onset: in that case, go to the emergency department, as it may be an acute obstruction.
How it's diagnosed
Diagnosis starts with the clinical history and examination of the pulses in the leg. The simplest initial test is the ankle-brachial index, which compares blood pressure at the ankle with that at the arm and gives an indication of the degree of obstruction. It's painless and non-invasive.
To pinpoint exactly where and how much the artery is narrowed, Doppler ultrasound is used and, if treatment needs to be planned, imaging tests such as CT angiography. With that information, the right approach is decided.
Sometimes it's necessary to make a differential diagnosis with other conditions that present with similar symptoms, such as neurogenic claudication, which also affects the lower limbs and can be disabling.
What treatment it has
The first treatment isn't the operating theatre: it's changing what damages the arteries. Quitting smoking is the most effective measure. Added to this is an exercise programme (walking until the pain appears, resting and repeating), controlling diabetes, blood pressure and cholesterol, and the medication prescribed by the specialist.
When claudication severely limits daily life or critical ischaemia is reached, restoring blood flow to the artery is considered. There are minimally invasive endovascular techniques (for example, angioplasty or stenting, via catheterisation) and, in selected cases, surgery using bypass or other techniques. You can see the details on the peripheral arterial disease treatment page.
In summary
Leg pain that appears on walking and goes away on stopping isn't just "normal for your age": it's a warning that your arteries may be diseased. The sooner it's assessed, the more options there are to slow the disease down before reaching the severe stages. If you recognise this pattern, ask for a vascular assessment and review your overall cardiovascular risk with the specialist.