WASHINGTON (AP) _ A study to test the conventional wisdom that low back pain can be limited by strengthening muscles around the hip has found that the training didn't help.
The study doesn't establish that what's called core conditioning is worthless for fighting low back pain, but researchers say it casts doubt on the value of the exercises they examined.
``Did we prove a change in muscle strength? We did,'' said researcher Scott F. Nadler. ``The thing we didn't show was that the strengthening reduced the incidence of pain.''
Nadler, of the University of Medicine and Dentistry of New Jersey in Newark, was lead author of a report in the American College of Sports Medicine journal, Medicine and Science in Sports and Exercise.
The article examined the value of exercises to strengthen primarily muscles of the abdomen, lower back and buttocks. These exercises, including sit-ups, pelvic tilts, squats and lunges, constitute traditional forms of core conditioning.
The added strength is supposed to ease strain on the back by improving posture and by giving the back more support as it bends and twists in sports or activities of daily living. However, the theory has never been tested rigorously in an experiment, Nadler said.
Nadler and his colleagues looked at NCAA Division I male and female athletes at a college in New Jersey. In the 1998-99 season, 164 athletes did their normal training but were given no special core conditioning program and served as the comparison group for the study. In the 1999-2000 season, 236 athletes were given additional core conditioning training, and served as the experimental group.
Researchers compared the incidence of low back pain complaints in the two groups, and found no statistically meaningful differences. Complaints were less common in men who did core conditioning, but the difference was too slight to let researchers statistically rule out the possibility that the apparent benefit was simply the result of chance.
However, there were relatively few complaints of lower back pain _ 14 in each year _ so it is possible that a significant difference could have turned up if there had been more cases, Nadler said. Also, different exercises than the ones studied might provide protection, he said.
Athletes in his study did exercises in which movement is tightly controlled, and protection against low back pain might require exercises based on more fluid movements, in which the back is in varied positions, Nadler said.
``I wouldn't say my results are saying don't do it,'' Nadler said. ``It just tells us we might not be right on the money right now with what we are doing.''
Leaders in exercise science are not giving up on core conditioning as a way to avert low back pain, despite the new study's findings. Their clinical experience indicates to them that the exercises work.
``Get a strong stomach and a strong back and stand up straight, and you are likely to keep your back in its best position,'' said Dr. Angela D. Smith, an orthopedic surgeon at Children's Hospital of Philadelphia, and president of the American College of Sports Medicine. The Nadler study is a good start, but more rigorous research is needed, she said.
The other experts have varying ideas on how core conditioning should be done. Smith, for instance, calls for strength building exercises followed by movement exercises.
At Georgia State University, professor Walt Thompson believes the problem is that shortened muscles in the back of the leg pull the pelvis out of alignment. ``I would suggest they should concentrate on hamstring flexibility,'' he said.
Reebok's approach is to develop the ability to respond to being off-balance. Reebok Core Training centers on its Core Board, which twists and tilts. The exercises let muscles get stronger as they react instinctively to changes in posture, said Gray Cook, a Reebok trainer and a physical therapist in Danville, Va.
However, Reebok's program also has yet to be proved against low back pain, said Cook and researcher Reed Humphrey of the Medical College of Virginia, who is a consultant for the corporation.
More research is needed into the causes of low back pain, and then a program can be based on those results, Cook said.
``The idea of training the core is empirically sound,'' Humphrey said. ``It makes sense. But the truth is, we don't know that. It's been this assumption.''