We're all running around like crazy these days -- cramming errands into already hectic schedules, coping with job stress, and picking up young children (literally!) --so our backs have a pretty heavy burden to bear. It's no wonder lower-back pain is the second most common reason (after colds) that people under 45 see a doctor. In fact, 90 percent of Americans experience backaches at some point, usually starting between their 20s and their 40s, says Todd J. Albert, M.D., professor and vice chairman of the department of orthopaedic surgery at Thomas Jefferson University Medical College and a director of reconstructive spine surgery at the Rothman Institute in Philadelphia.

Fortunately, you don't have to put up with a back that's always hurting. The vast majority of recurrent backaches get better without surgery or other serious treatments. Here we've identified some unexpected causes of back pain and ways to find fast relief:

Culprit #1: Smoking

A recent study at the University of Pittsburgh found that smokers report more severe as well as longer-lasting backaches than nonsmokers do. Why? One explanation is that "nicotine constricts blood vessels, reducing the availability of nutrients and oxygen to the disks in the back," says Jeffrey Gross, chief of rehabilitation medicine at Beth Israel Medical Center in New York. Research had found that this nutrient deprivation can accelerate disk degeneration, causing back pain.

THE FIX: Kick those butts now. Support groups, nicotine patches, gums, inhalers, and nasal sprays all can make breaking the habit a little easier. Ask your doctor which strategy is right for you, or go to the Center for Disease Control's website, at cdc.gov/tobacco/how2quit.htm, for advice.

Culprit #2: Being out of shape

If your ab and back muscles are weak, your spine may not be getting the support it needs, making it more susceptible to injury, notes Nayan Patel, a physician specializing in physical medicine and rehabilitation at the Texas Back Institute in Plano.

THE FIX: Make exercise a priority. Walking and riding a stationary bike are good activities for strengthening the back because they're low impact, meaning that you won't risk injury. So are stretching and strengthening the muscles in the abdomen, hips, and back.

Culprit #3: A worn-out mattress

A poor mattress makes your body form a C --an unnatural curve that shifts your spine out of its normal alignment, leading to wrenched muscles. And that's true whether you're lying on your back, side, or stomach.

THE FIX: Inspect your mattress for frayed edges, worn fabric, sagging in the middle, and other signs of wear and tear. If you see any of these, consider replacing it. When shopping for a new mattress, look for a firm one with a soft covering that cushions the contours of your body and provides gentle support. Says Patel: "You want one that's not too soft or too firm, something that conforms to your body. It should maintain even support and pressure across the shoulders, hips, and legs."

Culprit #4: Carrying around extra pounds

That additional weight places added stress on your back muscles. "Your center of gravity --where the motion of our entire body is centered --is located right around your lower back. If you're carrying any extra pounds, that delivers a lot more force on the spine," Patel explains. This makes the muscles work harder to perform everyday activities. If the back muscles can't handle all the lifting, your disks and spine feel the strain.

THE FIX: Slim down by cutting 250 calories from your daily diet and burning an additional 250 calories through exercise. A brisk 45-minute walk during your lunch hour will help you lose one or two pounds a week, says John Foreyt, Ph.D., director of the Behavioral Medicine Research Center at Baylor College of Medicine in Houston, Texas. For smart calorie-cutting advice, go to efit.com.

Culprit #5: Lifting objects or your kids incorrectly

Most of us tend to bend at the waist rather than squat when lifting --a big mistake. That's because bending at the waist requires you to lift weight using your back muscles instead of your leg and stomach muscles, which are stronger, explains Winifred D. Bragg, a physician specializing in physical medicine and rehabilitation with Orthopaedic Associates of Virginia.

And a word of caution for moms: wearing a baby carrier in the front can cause back pain by throwing your spine out of its natural alignment. As soon as your child is old enough, use a back carrier to decrease the strain.

THE FIX: When picking up a child or heavy object from the floor, squat and bring the object close to your body, tighten your stomach, and lift with your leg muscles. To protect your back when you lift your toddler, make sure he's facing you with his arms around your upper body and his legs around your waist; resting him on your hip places too much pressure on your back.

Culprit #6: High heels

They may be stylish, but they often cause back pain, Bragg says: "High heels --especially those with a thin heel or higher than two inches --thrust the body forward and throw the spine out of alignment, putting greater strain on the ligaments, lower back muscles, and disks in the back."

THE FIX: For all-day wear, stick with shoes that have a wide heel base and a heel no more than two inches high, Bragg says. Ditch shoes that cause you to walk with a pronounced arch to your back, make your feet wobble, or alter your natural gait noticeably. If you must wear sky-high heels, save them for a night out, not a day at the office.

Source: Colino, Stacey. (June 2003) The new way to beat back pain: surprising info on what causes the ache --and how to make it stop. Redbook Healthbook