Breath energy is the most fundamental element of living, and also an integral part of sexual energy. Breath energy follows a specific path during inhalation and exhalation: inhalation lifts chi up the spine and then it descends down to the pelvis during exhalation. Inhibited breathing may not adequately rise up the spine. Highly excited breath energy may rush up the spine and keep going.
Practices that emphasize the rushing phenomenon of excited energy in a sexual context are sometimes popularly referred to as tantra, although the title is probably more appropriate for a broader school of practice. The strong phenomenon of breath energy rushing up the spine, especially associated with sexual activity, may lead to intense (sometimes disconcerting) events.
As noted in this website’s essay on Breathing, an old Chinese meditation text describes descending exhalation chi as energy of function. In physiological terms, functional energy in the front path can be associated with digestion and related functions that may correlate neurologically with the vagus nerve.
In tai chi chuan and related practices there is an important place below the navel in the pelvis referred to as the lower tantien. When chi flows through the tantien one feels rooted, connected to the earth. Regular breathing cycles with exhalation through the tantien have a grounding effect that contributes to healthy energy, including sexual energy.