Have low-back pain? Ever had it? Want to avoid it? OK, that covers all of us, so listen up: The muscles of the lower back are designed more for stability and less for power or acceleration (unlike, say, the quadriceps). Thus, you want to choose back exercises that promote endurance, not brute strength.

Some experts even advise against common back exercises, arguing that those moves put undue pressure on the spine and are setting people up for injury. Suspect exercises include the Superman, Roman Chair back hyperextensions and reverse ab curl.

So, instead of playing Charles Atlas by doing back extensions while clutching a weight plate the size of Will Farrell behind your skull, you could have gotten away with much mellower work. In fact, you may have been hurting yourself.

Most back-specific exercises “apply a compressive penalty on the spine,” says New Jersey chiropractor Kenneth Cieslak, a noted expert on back pain who often treats athletes. He spoke on the topic at last month’s National Strength and Conditioning Assn. conference in Washington.

That doesn’t mean every back extension will hurt you, just that, over time, overloading your spine – a relatively fragile structure – can damage disks by subjecting them to excessive pressure.

“Almost all spine injuries are cumulative,” Cieslak explains, and result from long-term repeated loading on the disks. “People bend down to pick up a pen and their back goes, and they think that did it. But rarely (did) one episode cause it.”

Now, the good part. Some simple exercises condition your back and core muscles to provide stability with less risk to the spine:

¢ Curl-ups: Lie on back, feet together, knees bent, arms folded across chest, and slowly curl up until your shoulders and upper back – but not lower back – are off the floor. Lower and repeat. This strengthens the transversus abdominis (a deep abdominal muscle), which greatly aids support of all musculature in the low back.

¢ Planks: Face down on floor, prop yourself up on both elbows, then bring your body up so that your points of contact with the floor are toes, elbows and forearms. Keep your body tight and, especially, don’t let your middle sag.

¢ Side bridging: Lie on your side, prop yourself on one elbow so your biceps is perpendicular to floor. Lift your hip up so you’re supporting yourself on that elbow and the side of your foot. Engage core muscles to keep torso rigid, a straight line from heel to shoulder. Switch sides.

¢ Bird dogs: From all fours, with back straight, stick one arm out in front of you, in line with the plane of your back. Hold for two seconds and slowly return to starting position. Once you can handle it, also stick the opposite leg out behind you. Then switch sides.

Start with 10 repetitions of each, holding each for three seconds, then gradually work up to more, and longer, reps.

Cieslak and other experts caution against back-stressing activity – including running and rowing – in the first 45 minutes after waking up. (A disproportionate number of back injuries occur during morning exercise.)