What term is used to describe muscle tension that may lead to grimaces and spasms during sexual activity?

The term that describes muscle tension leading to grimaces and spasms during sexual activity is myotonia. Myotonia refers to prolonged muscle contraction and difficulty in relaxing muscles after voluntary contractions. During sexual activity, the body's physiological response includes increased muscle tension, and myotonia can manifest as involuntary spasms or tightness of the muscles, which may be noticeable as grimaces or muscle contractions.

In contrast, resolution phase refers to the body's return to baseline after sexual arousal, ejaculation refers specifically to the expulsion of semen during orgasm, and plateau phase is a stage in the sexual response cycle where excitement peaks before orgasm. Understanding these terms in the context of sexual physiology helps clarify the distinct processes that occur during sexual activity, underscoring why myotonia is the correct answer in relation to muscle tension effects.