It is physical exercise. No matter if you are a young man or an elderly woman, an overweight manager or a delicate young mother pregnant with her second baby: Exercise most likely will help you against recurrence of low back pain, according to Israeli guidelines based on a big number of published studies worldwide. - (Picture by Avril Hodge @ Flickr)
Exercise is the only recommendation that deserves an A rating, the researchers say. Lumbar supports, shoe insoles and «back schools» have not found to be effective. They may help in some cases but fail to help in others. On a general level they should not be recommended, only with much caution in special cases.
If you suffer from low back pain at the moment, you are well advised to consult your doctor and be very careful with exercises. They are not a treatment but rather a prevention of future pain attacks. Best are exercises that strengthen the trunk muscles. This is the only thing that can be said on a general level. You have to find out yourself (with the help of your physician or chiropractor or fitness instructor) what amount, duration, frequency and kind of physical exercises will do best for you.