I have heard about vibrations during meditation but I feel more of a slow throbbing through my body and sometimes swirling around my spine. What if anything does this indicate?
—Michael pare, Usa
What you could be experiencing is the Kundalini energy described in yoga teachings. Kriyananda has fully described this energy in his The Art and Science of Raja Yoga, a complete book describing the yoga teachings as given to him by Paramhansa Yogananda.
In Step 12 – “The Anatomy of Yoga” – Kriyananda says, “Through the medulla oblongata energy enters the body from the cosmic source.” It will lodge in the base of the spine to be brought up the spine when the individual positively directs his consciousness upward.
It is not to be feared but definitely you would want to direct this energy flow by concentrating at the point between the eyebrows, the spiritual eye. Bringing the Kundalini up the spine is the goal of many meditators as it brings enlightenment.
This is a big topic, so I would encourage you to look up The Art and Science of Raja Yoga on-line, and read about this wonderful energy flow.
Joy to you, Seva