When your back hurts, getting off the couch may be the last thing you want to do—but you should probably make it the first. New research shows that exercise is exactly what you need, provided it's the right type.

Researchers at UCLA studied 610 men and women with a history of chronic lower-back pain. After 1 1/2 years, they found that patients who exercised regularly were 31% less likely to experience an increase in pain and disability than their sedentary counterparts.

Surprisingly, those who regularly did back exercises—such as the stretches and strength-training routines often recommended by physical therapists—were more than twice as likely as those who didn't do those moves to complain of an increase in pain. Study author Hal Morgenstern, PhD, suspects that many people do those back exercises incorrectly, which exacerbates their pain.

Your best bet: a daily half-hour of aerobic activity, such as brisk walking or swimming, most days of the week.