Dr. Lin: 11/24/2000>
The energy coupling between two bodies during lovemaking requires activation of nervous systems.
To absorb energy from lovemaking, she or he has to turn on the sensory-parasympathetic nervous circuits.
On the other hand, the sensory-sympathetic nervous circuits is to give a way sexual energy, (orgasm). Of course, one can partially re-couple (recover) the orgasmic energy back to the spinal/central nervous system and brain via the S2-S4 three-way interneuron switches from the sensory-parasympathetic nervous circuits.  Thus, men and women can have a great benefit from sexual orgasm which converts the excessive testosterone into the parasympathetic bioelectric energy to supercharge all the internal organs.  This allows the parasympathetic nervous system to immediately re-start the endocrine function for generation of DHEA (Kidney Yin Chi)  and testosterone (Kidney Yang Chi).  Otherwise, ejaculation will make men feel fatigue and exhaustion.
The resting potential of the parasympathetic nervous system is the healing power generator and organ-charge actuator. When it charges the sex organ, it actuates the penis, clitoris and G-spot (Urethral/vaginal spongy tissues) to erect. That is why the erection of penis, clitoris and urethral/vaginal spongy tissues is a measure of vitality (body age).     
Sexual energy can be generated by converting Testosterone into bioelectricity (Chi) by sexual Chikong exercises, muscular exercises, or sexual stimulation. This is called Jing-Chi  (testosterone-bioelectricity) translation. Most of the muscular exercises are to burn testosterone for charging the dopamine and sympathetic nervous systems as Yang Chi or Wei (defense) Chi, respectively.  Sexual ChiKong exercises doing on the muscles in the pelvic cavity mainly target the parasympathetic nervous and acetylcholine systems (Yin Chi).
That is , during intercourse she has to exercise her vaginal/tailbone muscles to open her sensory nervous circuits and the Governing Vessels of the acupuncture network. Both sensory-sympathetic and sensory-parasympathetic nervous circuits from the urethra/vagina  to the anal/tailbone are somewhat equally active. The sympathetic nervous circuits are responsible for sexual orgasm while the sensory parasympathetic nervous circuits, responsible for swelling the sex organs to ultimately lead to the sympathetic orgasmic response, are very useful in recycling sexual energy back to the brain upon practicing the Jing-Chi translation exercise during lovemaking or meditation. Lovemaking in this way will effectively burn testosterone into sexual energy for fully erecting her urethral spongy tissues from the clitoris to the Epicenter via G-spot. Thus, practicing the Jing-Chi translation can bring her to super Level-7 orgasm. Conditions for the super Level-7 orgasms are:
1. Retaining a higher nervous trans-conduction with the sufficient  neurotransmitter acetylcholine in the interneurons (inter-connectors or switches), effectors (output) and receptors (input), where acetylcholine is responsible for the sensory sensitivity, motoring responsivity, and conductivity of the nervous circuits  ( No acetylcholine, no nervous conduction !);
2. A continuous burst and burning of testosterone (the Kidney Yang Chi) with DHEA (the Kidney Yin Chi)  to charge the nervous circuits during sexual encounter,  where the Kidney Yin (DHEA) must continuously assist (convert) the Kidney Yang (testosterone), in order to continuously erect her entire urethral spongy tissues (her female "penis") from her clitoris to Epicenter;
2. Practice of the 4-point Excitation Method for lovemaking with a hard penis which is a pre-requirement in order to lock into her Epicenter, the gap between her bladder and cervix..