Muscle vs. Joint Soreness
If you've recently started my Science of Stretching Program and are experiencing lower back pain after a day or two, it might actually be muscle soreness. This is common, especially if you haven't done these sorts of exercises in a while, and your body is still adjusting to the new movements.
The good news is that this type of pain usually subsides within a couple of days. Unlike joint soreness or spinal compression, which are more persistent and take longer to heal, muscle soreness is a sign that your body is adapting and getting stronger.