Hi Kevin,
Soreness in terms of the movement training is typically a sign that you are beginning to do the movements in a new way. The body is experiencing a new place that it may have never been in before. This is a good sign and means you are moving in a new and more complete way so the body is opening up to accommodate for these new movements. The stretching routine and the stretching regression routine are designed to support the new movements and open up the body while reducing soreness. Should the soreness grow into pain and linger for longer than a couple weeks we suggest reaching out to perform either an online follow up, swing submission, or find a local Tathata Movement Specialist to view and enhance your movements to ensure you are performing them safely and correctly.