A new study reinforced what physical therapists have long suspected: Massage, when coupled with traditional medical treatment, provides significant relief from chronic back pain.

That’s good news for the 70 percent to 85 percent of Americans who experience back pain at some time. It’s the most frequent cause of limited activity in people under 45, according to the National Institutes of Health.

Findings of the study, conducted by Seattle’s Group Health Research Institute, were published recently in the Annals of Internal Medicine. They suggest that massage therapy provided greater back pain relief than conventional approaches alone. Massage recipients spent fewer days in bed, were more active and took fewer medications. Research suggests massage stimulates injured tissue and calms the central nervous system.

Nobuku Anderson, 68, was among the 400 members of Seattle’s Group Health Cooperative whose persistent back pain led them to participate in the study.

For decades, she’d kept back pain at bay with regular exercise, sporadic massage and trips to the chiropractor. She also occasionally took aspirin. When she tried to carry a case of wine into her three-story townhouse one day in 2006, the pain seized her almost immediately.

She recuperated, but never fully. The pain was still there. Anderson was paired with a physical therapist, who in 2008 suggested she join the institute’s clinical trial. She would continue regular treatment with a weekly, hourlong massage.

“Almost immediately, it felt better and (relief) lasted a couple of days” she said, adding that subsequent massages offered longer relief.

At 10 weeks, more than one in three patients who received massages said their back pain had lessened or ceased. By comparison, one in 25 patients who got usual care reported improvements.

The study also found that after six months, massage recipients still reported pain relief. After one year, reported benefits were no longer significant.