The energy of attention stimulates latent apana. Because of the sexual nature of the pelvic prana, sensual arousal might occur. Just observe and accept. There is no need to censure the experience. Enjoy the meditation in observer consciousness.
After a set number of breaths, the attention moves up to the first chakra. If the meditator has time, he or she can relax into the experience and allow attention to percolate up to the sacrum on its own. The first chakra is awash with the color red. When initially meditating, all the aspirant needs is to be aware of is the color expressed through each chakra. With practice, all that will be necessary is to touch the front of the body over a particular chakra and the color associated with it will appear before the mind’s eye. Relax into the hue, feel it as much as visualize it. The shade of the color may vary from meditation to meditation and can be an indicator of the influences the person is presently under.
WEIGHT LOSS THROUGH YOGA, JEWEL IN THE LOTUS page 60