Oxytocin, Orgasm, Muscle Contractions, and Blood - A Journal Article I Read

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Here's a little SSL blog segment I'm going to call "A Journal Article I Read." I'm going to try my best to give you a super quick overview of, well, a journal article I read. Unsurprisingly, they'll have something to do with orgasm or sexual response or something along those lines. I figure that if I'm reading them, I might as well relay the knowledge I gained to you all. The biggest challenge will be for me to be succinct. I am long-winded. I know this, and I try to keep myself in check, but it's hard. Plus, there's a lot of detail in a journal article, and the details are really where the interesting bits come from, but I can't just rewrite the thing. I have to make some choices. I will do my best though, so here goes.

"Relationships Among Cardiovascular, Muscular, and Oxytocin Responses During Human Sexual Activity"
Carmichael, et al. Archives of Sexual Behavior Vol. 23, No. 1 1994

• 13 and 10 men all in good health got in an arm chair alone in a room (one at a time of course), got a blood pressure cuff on, a small anal probe up the butt to collect pelvic muscle activity and pelvic blood pulse amplitude information (because these were collected anally, the results of males and females could be compared directly), and a blood collecting needle in their forearm. They were free to watch porn if they so chose.

• Before the actual test days, each participant did all that without data being collected on a few different occasions till they felt comfortable. Then, they were each tested on at least 2 occasions. They masturbated to orgasm using whatever technique they normally used (how exactly they actually stimulated themselves was not disclosed). They used a foot pedal to signal the beginning and end of their orgasm. This way their subjective identification of orgasm could be compared with the objective physical measures of orgasm. They were then questioned afterward about their subjective feelings about the orgasm they just had - how intense, etc.

• So...In the end the scientists had the following data for 23 people from 6 minutes before they began self-stimulation to 5 minutes after their (final) orgasm:

1. blood samples at 6 points during the experiment for testing Oxytocin levels
2. continuous monitoring of pelvic muscle activity during length of experiment
3. continuous monitoring of blood pulse amplitude during length of experiment
4. blood pressure readings every 20 seconds during length of experiment

Results

• 9 women and 9 men all were mono orgasmic
• 4 women and 1 man were multiorgasmic (the multiorgasmic women all had 2 orgasms, and the multi orgasmic man had 5, with the final one including an ejaculation also)
• "There was no statistically significant difference between men and women or between mono-orgasmic and multiorgasmic women in duration of self-stimulation and orgasm or number of contractions during orgasm time, length of orgasm or contractions had during the orgasm." (p 64).

• In both men and women, from baseline readings through orgasm, there was a high positive correlation (meaning when one gets bigger the other gets bigger and when one gets smaller the other gets smaller) between Oxytocin levels (OT) and blood pressure; also between OT and muscle tension/blood pulse amplitude prior to and during orgasm.

• 2 patterns of orgasmic contractions were identified. 

1. "Type A is characterized by a continuous series of contractions whose frequency decreases with the passage of time" (p 69-70). 
2. Type B is characterized by one or more "breaks" occurring for 2-3 seconds followed by resumption of rhythmic contractions or several regular contractions. 
3. Type B correlated with higher Oxytocin levels, longer orgasms and more contractions during the orgasm. 
4. 2 mono-orgasmic women, 1 mono orgasmic man and 3 multi orgasmic women displayed Type B orgasms for both experimental sessions. 
5. 2 mono-orgasmic women, 2 mono-orgasmic men, the remaining multiorgasmic woman and the multiorgasmic man displayed type B orgasms for 1 of the 2 experimental sessions. 

• Only for multiorgasmic women was there any significant correlation between their subjective description of orgasm intensity and levels of oxytocin and with muscle activity intensity. 
• No significant correlations were found among the subjective ratings of intensity, pleasure, or satisfaction of orgasmand the number of contractions during orgasm, duration of orgasm, blood pulse intensity during orgasm, blood pressure during orgasm, or pattern of orgasm.

SSL significance: It confirms that the standard physiological identifiers of orgasm (muscle tension, pelvic blood congestion, blood pressure) described first by Master's and Johnson do indeed coincide with subjective experience of orgasm. It also confirms that males and females have rather similar physiological orgasmic experiences; that women don't take a lot longer or have particularly long or strange "types" of orgasms. However, unlike Master's and Johnson's studies, it did not find that the amount of contractions a woman had during her orgasm correlated with how intense she subjectively found the orgasm to be. It also points out that oxytocin, which is involved with uterine contractions during labor and with  milk cells for lactation, is also highly involved in sexual arousal and orgasm in both men and women - which is kinda old news, but to be fair, this was from 1994.