Surprisingly about 90 percent of all back pain goes away without any treatment within a week or two. In some cases it takes up to six weeks for a full recovery. In a small number of people (10 percent) back pain becomes a chronic problem over months and even years.
Many studies have been done comparing different ways to treat acute back pain. Information and advice from the doctor seems to work as well as any other treatment. A recent study of information and advice compared to information, advice, and group exercise showed the exercise group went back to work sooner.
In fact, after two weeks at the gym (three times a week), the group returned to work a full week sooner than the group who just got the information and advice. The exercises done in this group were geared toward back and abdominal muscles. Some spinal stabilization exercises were also done.
More studies are needed to find out exactly which exercises are best. Most research done so far seems to suggest any kind of exercise in any amount seems to work.