Anal Contractions During Orgasm / General Suggestions and Ideas / Fek
Eleven nulliparous women manually self-stimulated to orgasm, each on three separate occasions. Pelvic contraction pressure was measured by an anal probe and a vaginal probe simultaneously. Near the perceived start of orgasm, a series of regular contractions began in nine of the women. Anal and vaginal contraction waveforms were synchronized with each other, and the same number of orgasmic contractions occurred in each lumen.
This suggestion is for both male and female characters to have anal contractions while having an orgasm. Anal contractions could result from other stimuli too, though I don't have any ideas on that front. That I found "visual documentation" porn didn't surprise me. Much to my surprise looking up the topic I found medical documentation on anal contractions. For science
Vaginal contractions are contractions of the pelvic muscles surrounding the vagina , especially the pubococcygeus muscle. Vaginal contractions are generally an involuntary muscular response to sexual stimulation , including sexual arousal , and are commonly most intense during sexual stimulation and culminating in orgasm. Though usually an involuntary response, some women can control the muscles of the vagina to perform vaginal contractions at will. Vaginal contractions enhance the sexual experience and pleasure for both parties during sexual intercourse. In a study, pelvic contractions of 11 women who manually self-stimulated to orgasm were monitored using an anal probe and a vaginal probe simultaneously.