A vigorous contraction of muscles in the pelvic area expels or dissipates blood and fluid from the area of congestion. The average number of contractions for a woman is 8 to 15 contractions at intervals of 1 every 0.8 seconds. 

In men, muscle contractions surrounding the seminal vessels and prostate project semen into the proximal urethra. These contractions are followed immediately by three to seven propulsive ejaculatory contractions, occurring at the same time interval as in the woman, which force semen from the penis.