When walking becomes a pain

Walking can be hampered for a number of reasons, such as arthritis, a joint injury, or muscle strain. With these conditions, you most often already have pain before you begin walking.

But if you are pain-free and then pain arises as you walk faster or longer, it could be a vascular or nerve cause, especially peripheral artery disease, sciatica, or lumbar spinal stenosis.

Ironically, the best strategy when facing these is to keep walking and stay active, even if it means a little more pain with movement.

Peripheral artery disease (PAD)

PAD occurs when the arteries that carry blood to the leg muscles narrow, most often because of a buildup of fatty plaque.

The first PAD symptom typically is pain in one or both legs when walking that goes away when you slow down or stop. When you walk, your leg muscles need more blood flow to deliver oxygen to the muscles. Narrowed leg arteries won't allow the blood flow to increase, so the muscles hurt from a lack of oxygen. With severe PAD, people can develop leg pain at rest.

Plaque buildup can affect more than the legs. "If you have blockages in your leg arteries, you probably have blockages in the arteries leading to your heart and brain, which can raise your risk for a heart attack or stroke," says Dr. Mohamad Hussain, a vascular and endovascular surgeon with Harvard-affiliated Brigham and Women's Hospital.

Diagnosing PAD begins with a detailed review of your symptoms and a physical exam. Your doctor feels the pulses in both legs and feet to identify any reduction in blood flow. The next assessment is often a comparison of the blood pressures and blood flow in your legs versus your arms using ultrasound and a blood pressure cuff. This allows a calculation of the ankle-­brachial index, a more accurate indicator of PAD. Depending on the results, your doctor might also order an imaging test, such as ultrasound, CT, or MRI, to identify artery blockages.

Unfortunately, PAD can't be cured once you have it. The goal is to control its progression by addressing the main risk factors. That means adopting a heart-healthy diet, not smoking, and beginning a regular walking program.

"Walking increases blood flow in the smaller arteries of the legs and helps create new channels to move blood around the blockages," says Dr. Hussain. "This, in effect, brings more blood flow and oxygen to your leg muscles."

Of course, if you have PAD, walking is the ultimate Catch-22 — it helps the condition, but can also cause pain. The solution is to begin slowly and pace yourself. Walk every other day at first, and then progress to more days and longer periods.

"As you improve, you should find that walking becomes easier and you have fewer stop-and-rest periods," says Dr. Hussain. "Eventually, you want to build up to walking for at least 30 minutes at a time, five times a week. This is a good target to help prevent PAD, too."

Sciatica

Sciatica is the term for pain that happens because of pinching or irritation anywhere along the route of the sciatic nerve, which runs from the spine through the buttock and down the leg.

Symptoms of sciatica can vary from dull soreness, numbness, or tingling to feelings of an electric shock, throbbing heat, or stabbing pain. While increased pain with walking may be one person's predominant symptom, usually there are other symptoms, such as low back pain and difficulty sitting.

A common culprit for sciatica is a herniated disc (also referred to as a ruptured disc, pinched nerve, or slipped disc). But the pain can also originate from arthritis, an inflamed or narrowed sciatic notch in the pelvic bone, or piriformis syndrome, in which the piriformis muscle in the buttock compresses the sciatic nerve.

Your doctor can often diagnose sciatica just based on your history and a physical exam. If the symptoms are severe or unusual, your doctor might order an imaging test, most often MRI. Once again, you need to find ways to stay physically active.

"Many people fear that activity will cause or worsen sciatica pain, but low-impact activity and exercise can help strengthen the areas along the nerve and prevent future attacks or at least lower their intensity and frequency," says Dr. Jeffrey N. Katz, a professor of medicine and orthopedic surgery at Harvard Medical School.

Examples include riding a stationary bike, doing daily back stretching, and yoga. "Physical therapy can also help strengthen muscles around the spine, which may take some pressure off your discs," says Dr. Katz. If the pain is especially intense or persists, you may opt for a corticosteroid injection or a short course of an oral corticosteroid, usually prednisone.

Lumbar spinal stenosis

In lumbar spinal stenosis, the space inside the lowest part of the spinal canal narrows, usually from degeneration of discs, ligaments, or any of the joints between the interlocking vertebrae that form the spine. This puts pressure on the spinal cord and the nerves.

Pain that occurs only when walking may be the only symptom of lumbar spinal stenosis. Many people discover that immediately squatting or sitting helps lessens the pain. Other symptoms include

• low back pain
• pain in the groin, buttocks, and upper thigh that does not move down the leg (unlike the pain of sciatica)
• pain that feels worse when you lean back and becomes less intense if you lean forward.

A definitive diagnosis of lumbar spinal stenosis usually requires an imaging test, such as an MRI or CT scan.

As with back pain, PAD, and sciatica, staying physically active is a must. Walk as much as you can tolerate. "Riding a stationary bike also can be a useful exercise," says Dr. Katz. Physical therapy is helpful, too: a physical therapist can guide you through maneuvers and exercises to maintain core and leg strength.

Over-the-counter or prescription pain relievers can ease discomfort. Your doctor may discuss corticosteroid injections, though the evidence is mixed regarding their effectiveness.

If your symptoms don't improve, surgery called laminectomy may be the next step. Here, the surgeon removes the bony plate on the back of the vertebra where the stenosis is located, which opens up more space for the spinal nerves.

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