When you are in significant pain.
A severe attack of lower back pain may involve pain that is felt at all times regardless of the position you adopt or the movements you perform. This pain is made much worse by sitting or by arising from a sitting position and bending forward. If the pain is also much worse when you attempt to stand up or walk, and if you are unable to straighten up fully, it may not be possible for you to function, and bed rest is your only alternative.
Recent research tells us that bed rest is not the best option for the treatment of acute and severe back pain and should be used for no more than two days. Those involved in that research, however, may alter their view if they ever personally experience a severe bout of back pain.
In my experience, there are many patients in severe pain who require longer than two days of bed rest before it is possible for them to walk. Nevertheless, early exercise and other movement is preferred for those forced to seek bed rest, and a determined effort to stand upright should be attempted at least once each day.
You may begin the exercise program during your period of bed rest, provided you can lie facedown for short periods. Perform Exercises 1 through 3