By Adam Hedaya, MD, pain medicine physician

The short answer: with lumbar spinal stenosis, standing up straight narrows the space around the nerves in your lower back, and bending forward opens it a little. That's why walking upright can bring on heavy, aching or numb legs, and why leaning on a shopping cart, a walker or a bike handle often lets you go farther.

What spinal stenosis is

Spinal stenosis simply means narrowing. In the lower back, the canal that carries the nerves to your legs can slowly narrow with age, from thickened ligaments, arthritis in the small joints of the spine, and bulging discs. It's one of the most common reasons older adults see a spine physician.

People with stenosis often describe it in very similar ways:

• "I can only walk for about ten minutes."
• "My legs feel like they weigh a hundred pounds."
• "I'm fine sitting down. It's standing and walking that get me."

Why standing and walking bring it on

The answer is spinal mechanics. When you stand upright or lean back, the spinal canal gets a little narrower. When you bend forward, it opens slightly. For someone with stenosis, that small change in space can make a real difference to how irritated the nerves feel.

That's why many people with stenosis notice that:

• Walking uphill is easier than walking downhill.
• Leaning on a shopping cart makes a trip through the grocery store possible.
• Sitting or bending forward brings relief within a few minutes.

Is it stenosis, or something else?

Two other problems can look similar, and the difference matters:

• Arthritis in the spine's small joints (facet joints) can also hurt more when you stand upright, but the pain usually stays in the back. Stenosis tends to send heaviness, numbness or pain into the legs.
• Poor circulation in the legs can also cause leg pain when you walk. The clue: simply stopping usually brings relief, even while you stay standing, and leaning forward doesn't change it. Weak pulses in the feet, cool or discolored skin, hair loss on the shins and sores that heal slowly point toward a circulation problem. Ask your physician to check.

How to walk farther with stenosis

Because bending forward helps, the most comfortable activities often keep you slightly flexed:

1. A stationary or recumbent bike. A favorite for people with stenosis, because you sit leaning a little forward.
2. Walking with support. A shopping cart, a walker or trekking poles let you lean forward slightly and walk farther. Using one is a tool, not a step backward.
3. Walking in a pool. The water takes weight off your spine.
4. Interval walking. Walk until symptoms first appear, then sit or lean forward until they settle, and start again. Over the weeks, try to lengthen the walking stretches a little at a time.

Small changes help with standing tasks, too. When you cook, shave or wash dishes, rest one foot on a low step or an open cabinet shelf. It tilts the pelvis slightly and can ease symptoms.

Will stenosis put me in a wheelchair?

It's one of the most common questions I hear. For most people, the answer is no. Many people manage stenosis well for years with the right activity, support and treatment. When conservative care isn't enough, there are other options, including injections, minimally invasive procedures and surgery, and your spine physician can talk through which ones fit your situation.

When to see your physician

See your spine physician if:

• The distance you can walk keeps shrinking over months
• You notice new weakness in your legs
• Your balance is getting worse

Go to the emergency room right away for:

• Sudden loss of bladder or bowel control
• Numbness in the groin or between the legs

The bottom line

Bending forward opens the spinal canal, and standing upright narrows it. Bikes, carts, walkers, poles and interval walking all use that fact to help you walk farther. And if your walking distance is shrinking, or you notice new weakness, it's time to be re-evaluated.

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This article is for education only and isn't medical advice. Please talk with your own clinician about your symptoms and treatment.