the last two days I have had what is best described as a muscle spasm/vibration in the root chakra area. It has happened about ten times between yesterday evening and this morning, especially during my practice fo asanas and pranayama. it can last for a minute at a time, anyone with any idea of what this may be?
Shakti. Any other effects such as hot and cold flushes, raised blood pressure, shivers down the spine, headaches? These are classic indicators of Shakti or kundalini awakening.
Enjoy. 
on friday after a class, my blood pressure was in the high range, 144/90 or something like that, normally I am 120/80 or so. No hot or cold flashes
The opening of the pranic sheath can make the walk into the vijnana sheath easier.Here there is also the enticing deviation of siddhis!