Two months ago I had a very successful operation for a herniated disc. Now I want to get on an exercise program. I'd like to keep up my strength and flexibility. How often should I exercise to get the benefit without hurting myself?

Many studies have been done to find the best rehab program after lumbar disc surgery. The results are good for several different approaches. Short-term intensive programs give the best results. Patients get more function and return to work sooner than patients in a mild exercise program.

Early intervention seems to work best. Patients who begin exercising right after surgery (up to six weeks after surgery) have better results than those who wait three months or more to begin.

Target frequency, duration, and intensity are still unknown. Studies show patients get better even with minimal exercise (twice a week). It may be that more is better, but the exact measure of exercise needed for best results remains a mystery.

A general guideline that seems to work well for many kinds of conditions, illnesses, and diseases is: moderate intensity exercise at least three times a week. Five times a week is even better. Daily exercise isn't advised. The body needs at least one day a week for rest and recovery.