Findings Exercise is a modestly effective treatment for chronic low-back pain, while TENS (transcutaneous electrical nerve stimulation) a treatment that stimulates nerves through electrodes on the skin, has not been proven effective, according to a thorough review of studies on the subject.

Exercise: Qualified Yes Exercise therapy slightly decreases pain and improves physical function in adults with chronic low-back pain but appears to do little for those with acute pain, say researchers who have studied the evidence. Jill Hayden, a research fellow at the Institute for Work & Health in Toronto, and colleagues examined 61 studies involving more than 6,000 adults with low-back pain.

Chronic low-back pain may come and go, while acute pain hits suddenly and intensely -- after lifting a heavy piece of furniture, for example. Acute pain lasts less than six weeks; chronic pain, more than 12 weeks.

"The accumulated evidence supports a sea change that has occurred in medicine, away from recommending prolonged bed rest and activity restriction," said Michael Von Korff, a senior investigator at the Center for Health Studies in Seattle who was asked to comment on the issue. "We now recommend aerobic, flexibility and strengthening exercises, and sensible resumption of normal activities as the worst pain subsides."

Electrical Stimulation: Not Proven Another approach to low-back pain, transcutaneous electrical nerve stimulation (TENS), has been used for more than three decades. But Lucie Brosseau of the University of Ottawa examined TENS research and found that only two studies involving 175 patients met the review's criteria for drawing conclusions. One study found a significant short-term benefit, but the larger, better-quality study found no effect.

"There may be some place for TENS as a component of treatment for people with chronic low-back pain," said Dennis C. Turk, a psychologist and pain expert at the University of Washington in Seattle. "But there is no evidence on which to base the conclusion that it is useful" by itself.

Details Both reviews appear in the current issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Summaries of the findings are available at

-- Health Behavior News Service

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