Harvard Health Letter

When walking makes your legs hurt

Four conditions that can affect your legs and make walking painful

walking pain, legs hurtFitness experts used to stress the benefits of heavy-duty aerobic exercise — the kind that makes you breathe hard and gets your heart going. But the message changed to moderation after a number of studies showed that physical activity that's far less taxing is associated with lower rates of heart disease, some cancers, and several other illnesses — if it's done regularly. Plain old walking usually tops the moderate-intensity exercise list because it's easy, convenient, and free, and it requires minimal equipment — a comfortable pair of shoes.

The trouble is that walking isn't so easy for everyone. Indeed, it's agony for many. And forget the "brisk" pace of three to four miles per hour advised for health and fitness.

With age — and occasionally without it — a number of conditions can result in leg pain that makes walking difficult. Some are very familiar, such as arthritis that makes knees and hips creaky; others, such as peripheral artery disease, aren't.

This article looks at four nonarthritic conditions that cause leg pain and may affect walking, and some ways to treat and manage them — no need to limp and bear it!

We're discussing these conditions separately, but people may have two or more of them at the same time, which complicates diagnosis and treatment.

1. Peripheral artery disease

Peripheral artery disease is a form of atherosclerosis, the same condition that leads to most strokes and heart attacks. Fat- and cholesterol-filled plaque narrows arteries, and blood clots can collect on the plaque, narrowing them further. In peripheral artery disease, the arteries affected by atherosclerosis tend to be the ones that supply the leg muscles. The risk factors are similar to those for heart disease and stroke: smoking, high cholesterol levels, high blood pressure, and especially diabetes.

The classic symptom is cramping, tight pain that's felt in muscles "downstream" from the narrowed artery. It can occur in the buttocks, thigh, calf, or foot, but occurs most often in the calf. The pain tends to come on with walking, get worse until the person stops walking, and go away with rest. Similar to angina, the pain caused by peripheral artery disease comes from working muscle cells that are "starved" for oxygen because of obstructed blood flow. The medical jargon for this kind of pain is intermittent claudication, from the Latin claudicatio for limping. Many people with peripheral artery disease have other sorts of pain, though. Sometimes their legs are heavy, or they tire easily. And it's common for people to cut back on their activity level without realizing it, which can mask the problem.

Signs of peripheral artery disease include a diminished pulse below the narrowed artery, scratches and bruises in the lower leg that won't heal, and pale and cool skin. The diagnosis usually depends on the ankle-brachial index, which compares the blood pressure at the ankle to the blood pressure at the arm. They're normally about the same, but if there's a blockage in the leg, blood pressure will be lower in the ankle because of low blood flow.

Arteries narrowed by atherosclerosis leave leg muscles starved for oxygen.

Peripheral artery disease by itself can be serious and debilitating, but it may also serve as an important warning of even more serious trouble. Atherosclerosis in the legs often means there's atherosclerosis elsewhere, and people with peripheral artery disease are six to seven times more likely to have a heart attack, stroke, or transient ischemic attack than people without it. A peripheral artery disease diagnosis should prompt a concerted effort to rein in cardiovascular disease risk factors.

Walking hurts, so a "just do it" attitude about exercise isn't helpful. But researchers have found that tightly structured, supervised exercise programs can help people increase the amount they can walk before the pain kicks in. These programs usually involve walking till it hurts (which may be only for a few minutes), resting till the pain goes away, and then walking again. These walk-rest-walk sessions are most effective if people do them for about 30 minutes at least several days a week.

Low doses of aspirin (75 mg to 325 mg) are often recommended to reduce the risk of heart attack and stroke. Clopidogrel (Plavix), another drug that makes blood clots less likely by making platelets less sticky, may be slightly more effective, but it's a lot more expensive. Cilostazol (Pletal), a drug that widens blood vessels, and pentoxifylline (Pentoxil, Trental), which decreases the viscosity of blood, can sometimes help improve pain-free walking distance, but both drugs have side effects, so there's a downside that needs to be taken into consideration.

Serious cases of peripheral artery disease can cause leg pain even when the person isn't walking. This "rest pain" most often occurs in the feet. Even more serious are cases when the condition leads to tissue death and gangrene.

If peripheral artery disease is serious, or isn't improving with exercise and medication, doctors can reopen the blocked artery with angioplasty or use part of a blood vessel from elsewhere in the body to reroute circulation around the blockage. But the track record of these revascularization procedures is mixed, and some studies suggest that the results from a structured exercise program can be as good, or even better.

2. Chronic venous insufficiency

Like peripheral artery disease, chronic venous insufficiency is a condition of poor circulation, but it involves the veins and the blood's return trip back to the heart and lungs.

Our arteries are springy and help push blood along, but our veins are relatively passive participants in circulation. Particularly in the legs, it's the muscles surrounding the veins that provide the pumping power that drains the vessels near the surface of the skin and then push the blood up through the "deeper" vessels that travel toward the heart. Tiny valves inside the veins even out the pressure and keep the blood from flowing backward.

In people with chronic venous insufficiency, the valves are damaged, so blood tends to pool in the legs and feet instead of traveling "north" to the heart. It's often a vicious cycle: if the valves aren't working, pressure from the blood collecting in the veins increases, so the veins stretch out. As a result, the valves don't close properly, so even more blood flows backward, adding pressure.

Symptoms include swelling, inflammation of the skin (dermatitis) and the connective tissue underneath (cellulitis), and ulcerated, open wounds on the bony "bumps" of the ankle. Legs may feel achy or heavy. And when people walk, they may feel a tight, "bursting" pain, most often in the groin or thigh. The pain will stop with rest but may take longer to ease up than the pain from peripheral artery disease.

Damaged valves in veins means blood may flow backward and accumulate in veins.

The symptoms from a mild case of chronic venous insufficiency can be helped by lying on your back and using a pillow to elevate your legs so blood flows downhill to the heart. If you're sitting for long periods, pointing your toes up and down several times can flex the vein-pumping leg muscles.

More serious cases needed to be treated with compression stockings that squeeze harder at the ankle than at the knee. For the stockings to work, they must be much tighter than the "antiembolism" stockings people routinely wear in the hospital. But because they are so tight, people often have a hard time getting them on. Washing a new pair can help. Some people coat their skin with talcum powder or wear thin, regular stockings underneath. Devices called "wire donners" hold the stockings open so people can push a foot and leg into it.

There aren't any medications for chronic venous insufficiency per se. A few studies have shown that a supplement, horse chestnut seed extract, reduces swelling and leg pain, but the studies have been short (only a month or so) and side effects (dizziness, upset stomach) have been a problem.

Surgical treatments are reserved for the most serious cases. They include removing damaged veins or tying them off (venous ligation). Studies have shown that surgery can prevent recurrence of skin ulcers.

3. Lumbar spinal stenosis

Stenosis (pronounced ste-NO-sis) is a medical term for any kind of narrowing. Spinal stenosis can occur anywhere along the spine as a result of the vertebrae, the disks between them, or their supporting structures impinging on the tubelike spinal canal that holds the spinal cord and the roots of the nerves that branch off of it. Pain comes from the mechanical pressure, and perhaps also from the pinching off of the blood supply that nerves (like any other kind of tissue) need.

The lumbar region of the spine consists of the five large vertebrae that form the small of the back. When spinal stenosis occurs in the lumbar region, lower back pain can be a symptom but often it's the legs that are affected. The pain can resemble the pain caused by peripheral artery disease: cramping tightness that increases with walking, although it's often felt in the thigh rather than the calf. The legs may also feel weak and numb.

In the past, the leg pain caused by lumbar stenosis was called pseudoclaudication because it was unrelated to blocked arteries, and doctors didn't understand that it could be caused by spinal problems. Now the preferred medical term seems to be neurogenic (which means originating from the nervous system) claudication.

Vertebrae, disks, and other parts of the spine impinge on the spinal cord and nerves branching off of it.

The diagnosis starts with discussion of symptoms and medical history. One important clue is whether the pain eases when the back is curved forward, or flexed. That posture tends to take pressure off the lumbar region, and it's the reason some people with lumbar spinal stenosis find it easier to walk when leaning on a grocery cart or a walker.

An MRI or CT scan will often be ordered to confirm a diagnosis, but imaging studies shouldn't be used to make one. Many people have spinal stenosis that shows up on an imaging study but doesn't cause any symptoms.

Treatment usually begins with physical therapy and exercises aimed at strengthening back and abdominal muscles. Pain relievers may help. Growing numbers of older patients are getting corticosteroid injections into the spine, which worries some experts. Evidence that the shots are effective is mixed.

If the pain persists, surgery is an option. The most common procedure is a laminectomy, which involves cutting away part of a vertebra to create more space for the spinal cord and nerves. Bone spurs and portions of the disks and facet joints can also be removed to relieve pressure. Study results for surgery are murky. The majority of patients seem to feel better for the first year or so, but the advantage over a nonsurgical approach seems to wear off after several years. A second operation is sometimes needed. On the other hand, for some, surgery greatly reduces the pain and discomfort.

4. Diabetic neuropathy

People with diabetes are prone to nerve damage, or neuropathy. Exactly why is uncertain. High blood sugar levels may damage the tiny blood vessels that supply nerves, creating "nerve strokes": nerves starved for oxygen (ischemic) because of damaged vessels. Diabetes may also deplete the body's store of neurotrophic peptides, chemicals that normally repair and regenerate nervous tissue.

Blood vessels (shown in red) that supply nerve cells can be damaged by high blood sugar.

Diabetic neuropathy affects the upper and lower legs in different ways. In the upper leg, the pain from ischemic nerves can come on suddenly and be felt in just one leg. In the lower legs and feet, where it is more common, the symptoms are typically numbness or tingling, and are usually felt about equally in both legs. The numbness often dulls painful sensations, so sores on the feet go unnoticed and get worse. Diabetic neuropathy can make walking difficult, but symptoms may improve with exercise.

People with diabetes can reduce their chances of developing neuropathy by keeping their blood sugar down. It's less certain that tight blood sugar control is helpful once nerves have been damaged. Still, it's an important goal for many other reasons. Pain relievers, tricyclic antidepressants (amitriptyline, desipramine), and anticonvulsants (carbamazepine, gabapentin) are used to control the burning and tingling sensations from neuropathy.

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