What Happens to Our Bodies During Sex

What Happens to Our Bodies During Sex. The sexual response cycle is how experts describe what’s going on inside your body that makes you feel and respond the way you do during sex.

Back in 1966, sex researchers William Masters, MD, and Virginia Johnson came up with the term. They defined four stages, or phases, of this cycle:

Phase 1: Excitement. As you get excited, your heart beats faster and your breathing gets heavier. Your skin may redden. More blood flows to your genitals. The clitoris swells and the penis gets erect. Nipples harden and the vagina may get wet. Muscles throughout your body tense up, boosting sexual tension.

Phase 2: Plateau. The changes in your body intensify. Breathing, heartbeat, and blood pressure rise. Muscle tension increases even more. The vagina swells and its walls turn a darker color. The clitoris becomes super-sensitive to touch. The testicles pull upward.

Phase 3: Orgasm. Sexual excitement reaches its peak. You feel a series of intense muscle contractions as your body releases the tension. The muscles of the vagina and the uterus contract. Muscles at the base of the penis tighten and release, releasing semen in an ejaculation.

Phase 4: Resolution. Now spent of your pent-up energy, your body returns to its pre-sex state. Your breathing calms. Muscles relax. The penis and vagina return to their original size and color. You may feel calm, satisfied, or tired out.

This four-phase cycle is a fairly simple way to describe the human sexual response. In reality, human bodies (and minds) are unique. The way we respond to sex doesn’t always fit neatly into four ordered boxes.

“Since the Masters and Johnson model, we’ve learned much more,” says Kristen Mark, PhD, the Joycelyn Elders endowed chair in sexual health education at the University of Minnesota Medical School. “One thing coming before another is pretty inaccurate to the human sexual experience.”