Masters and Johnson, the pioneering researchers into human sexuality, identified four stages of physiological responses during sexual stimulation, for both men and women. They named these four stages as:
- Excitement Phase
- Plateau Phase
- Orgasmic Phase
- Resolution Phase
We will consider the different physical manifestations of these four phases of sexual stimulation and response, in the human female.
Stage 1: Excitement Phase
Also known as the Arousal Phase, this is the first stage of the human sexual response cycle. It occurs as the result of any sexual stimulation, be it physical or mental. This can be erotic touching, kissing, petting, viewing sexy images, even imagining or fantasizing sexually exciting situations. During this phase, the body is preparing for sexual intercourse.
For the woman, the Excitement Phase causes the blood vessels in her genital areas to dilate, resulting in increased blood flow to her genitals. Her clitoris, vagina, labia majora and labia minora (outer and inner genital lips) all become engorged and swollen with blood. The enhanced blood supply to the vaginal walls leads to fluid passing through, to create vaginal lubrication, making her vagina wet. The top of the vagina expands as it gets ready for penetration by a penis. Her clitoris becomes erect and swollen, in a response similar to the male penile erection. The nipples become erect, especially if stimulated directly.
There is an increase in the rates of breathing, heart beats, and in the blood pressure. More than 50% of women also display vasocongestion of the skin, commonly referred to as the “sex flush”.
Stage 2: Plateau Phase
This second phase of the sexual response cycle is the stage before climax or orgasm. In this phase, there is a further increase in blood flow, rates of breathing and heart beat. Feelings of sexual pleasure increase with increased stimulation. The high blood flow causes the outer third of the vagina to become engorged and firm. The muscle around the vagina tightens, reducing the diameter of the vaginal opening, creating what Masters and Johnson refer to as the orgasmic platform. For those who never achieve orgasm, this is the peak of sexual excitement.
At this stage of sexual arousal and response, the woman’s breasts may increase in size by up to 25%. The clitoris withdraws slightly, while the areola and labia increase in size. At this point, the woman needs continuous stimulation to raise the level of sexual arousal to the point of reaching orgasm.
Prolonged time in the plateau phase without progressing to orgasm can result in sexual frustration.
Stage 3: Orgasmic Phase
The normal and expected progression from the Plateau Phase is to reach the Orgasmic Phase. In orgasm, the sexual tension built up in the earlier phases is released with intense and powerful feelings of sexual pleasure. Orgasm in women is accompanied by rapid cycles of contraction and release in the muscles surrounding the vagina and the anus, as well as contractions in the uterus. Involuntary sounds expressing pleasure, and muscular spasms spread throughout the body are commonly experienced by women in orgasm. Heart rate increases even further and there is a general feeling of intense pleasure and euphoria.
Unlike men, women do not need a recovery period after orgasm, and they can go on and have further orgasms if adequately aroused and suitably stimulated. This is known as female multiple orgasms.
Current thinking holds that female orgasm has a significant role in human reproduction. It is believed that the muscular vaginal spasms help move the sperm up the vagina and into the uterus for fertilization of the egg.
Stage 4: Resolution Phase
After orgasm, either single or multiple, the woman enters the resolution phase. Here her body gradually returns to its normal state. The muscles relax, blood pressure reverts to normal, rates of breathing and heart beat slow down to their unexcited states. There is a pleasant feeling of relaxation and satisfaction.
Female Sexual Stimulants
The four-stage sexual response cycle indentified by Masters and Johnson is virtually automatic for almost all men but, unfortunately, it is not so for many women. There are many women who are unable to proceed from the Excitement Phase through to the Orgasmic Phase – some surveys indicate that up to 40% of all women may experience this difficulty.
In addition, there is the question of duration of sexual intercourse. Often, sexual activity will end when the man has ejaculated – although it need not, and should not, be so. In such cases, often the woman has not had enough time to reach orgasm, especially if her man suffers from premature ejaculation – an all too common male sexual problem.
Studies have conclusively shown that sensitivity and response to sexual stimulation are increased and intensified when there is an increase in the flow of blood to the genital tissues – in the case of women, to the clitoris and vagina. The normal progress of sexual response in the Excitement and Plateau Phases depends on enhanced blood supply to these areas by dilation of the blood vessels.
Research studies have established that this dilation of the blood vessels is controlled by the level of nitric oxide in the body – if there is adequate nitric oxide, the blood vessels dilate to allow enhanced blood flow. Research studies have also established that the amino acid, L-arginine, creates nitric oxide in the body by a natural chemical reaction. Therefore, if L-arginine is supplied to the body by external means, there is significant enhancement of genital blood supply and, consequently, in sexual sensitivity and response.
It is this effect that enables a female sexual stimulant like Vigorelle, that is based on L-arginine, to enhance female sexual sensitivity and to help women progress through the four stages of the sexual response cycle, to experience the powerful pleasures of female orgasm.