Sooner or later, we’re all likely to develop lower back pain. Four out of five Americans do. In the vast majority of cases, the culprit is a sedentary lifestyle. Chronic inactivity weakens back muscles, making them vulnerable to strain. It also loosens the ligaments and tendons that support the spine and causes spinal discs to deteriorate.

Caution: See a doctor at once for back pain accompanied by loss of bladder or bowel control, sudden onset of weakness in the arms or legs, loss of weight or appetite, blood in the urine or stool or continuous pain at night. These symptoms suggest serious illness.

Back pain usually resolves on its own within 48 hours. To dull the pain during that time, apply ice to the affected area. Cold reduces pain by helping to curb swelling and inflammation.

Fill a plastic bag with ice cubes, then wrap the bag in a moist towel. Place the wrapped bag on your back, and leave in place for five minutes. If you leave the ice bag on longer than that, the cold temperature might damage your skin.

For back pain that persists beyond 48 hours, heat from a heating pad, hot shower or bath works better than cold. It dilates blood vessels, boosting circulation and speeding nutrients to damaged tissues.

What about painkillers? Acetaminophen (Tylenol), ibuprofen (Advil), naproxen (Aleve) and aspirin are equally effective.

Caution: If you experience stomach upset, nausea or diarrhea after taking an over-the-counter painkiller, stop taking it at once.

Until about 15 years ago, bed rest was the treatment of choice for back pain. Now we know that inactivity is one of the worst things you can do.

A fitness regimen consisting of aerobic exercise, strength training and stretching helps treat and prevent back pain.

If you’re temporarily hobbled by back pain, even a brief walk can be helpful. So can these pain-relieving exercises:

Back extension. Lie on your stomach with your hands flat on the floor by your chest. Press up so your chest and back arch slightly. Hips should remain flat on the ground. Hold for 10 seconds, then repeat several times.

Lumbar flexion. Get on your hands and knees, then arch your back upward slightly. Hold for 10 seconds, then repeat several times.

Everyone knows that it’s best to lift heavy objects using the legs, not the back. The idea is to let your strongest muscles do the work and protect the back from needless strain. Other smart moves:

Push rather than pull. Pulling a heavy object is more likely to strain back muscles than pushing.

Distribute carried weight evenly across your body. Do not heft a heavy object on one hip.

When unloading a car trunk, place a knee or foot on the bumper to improve your leverage.

Good body mechanics is also about what to do when you’re not moving. Sitting still for too long “starves” the back by decreasing circulation.

To avoid trouble: Get up and take a brief walk every 20 minutes. If that’s impossible, shift your seating position, stretch and/or do Kegel exercises. To do Kegels, repeatedly tighten your pelvic floor muscles (the ones you use to stop urine in midstream) for five seconds.

In addition to relaxing tense, painful muscles, massage improves circulation and raises levels of endorphins, the body’s natural pain-killing compounds.

Massage from a partner can be helpful, but it’s better to seek the services of a professional massage therapist. A one-hour session runs $50 to $60. You may need up to three sessions a week for two to three weeks.

To find a massage therapist in your area, contact the American Massage Therapy Association at 847-864-0123.

If you still think of acupuncture as “far out,” think again. In 1997, the National Institutes of Health, which is famous for its skepticism regarding alternative therapies, issued a report acknowledging that acupuncture can be helpful against lower back pain.

The procedure is relatively painless. Five to 15 thin needles inserted in specific locations on the body stimulate the release of endorphins.

An initial consultation with an acupuncturist costs about $100. Follow-up visits run $35 to $75.

To find an acupuncturist near you, call the National Certification Commission for Acupuncture and Oriental Medicine at 703-548-9004.

Magnets have become popular for treating back pain, especially among athletes. Worn in belts or taped across the back, they’re inexpensive and unobtrusive.

There’s still no good scientific evidence that magnets really work. But given their safety, they may be worth trying if nothing else works.

If the pain persists for more than a week, it’s time to consult a chiropractor or physician.

Chiropractors and physicians take different approaches to back pain. But both approaches (spinal manipulation by chiropractors and prescription painkillers or injections of muscle relaxants or steroids by physicians) are of proven effectiveness.

To find a chiropractor, contact the American Chiropractic Association at 800-986-4636.

Surgery should be considered only if pain remains unbearable after all other options have been exhausted.

To find a back surgeon in your area, contact the North American Spine Society, 6300 N. River Rd., Ste. 500, Rosemont, Illinois 60018. 847-698-1630.