During sexual intercourse, most women experience involuntary vaginal contractions. The contraction causes the pelvic muscles to tighten around the penis, which increases the level of her partner's arousal and sexual frenzy and results in the man increasing the pace and force of thrusts as he approaches orgasm, which in turn further increases the woman's vaginal contraction. After a man has achieved orgasm, he will normally collapse onto the woman and will normally not be capable of further thrusting. Some men try to control their orgasm until their female partner also orgasms, but this is not always achieved. At times, a woman can achieve orgasm after the man has ceased thrusting by contracting her vaginal muscles and with pelvic movements, or the couple may change to another position that enables the woman to continue thrusting until she has reached orgasm, such as a woman on top position.