Wiktionary
n. 1 sexual exercise; the performance of sexual activity as a means of promoting health and fitness. 2 Exercise that is directed towards the improvement of sexual performance.
Wikipedia
Sexercise is physical exercise performed in preparation for sexual activity and designed to tone, build, and strengthen muscles. Sexercises are often performed as part of a sex diet lifestyle, which seeks to maximize the health benefits of regular sexual activity. While sexercises are usually performed with a partner, solitary masturbation might be considered a sexercise if done athletically for health and fitness. Exercise is known to improve and quicken the flow of oxygenated blood, in higher and consistent amounts, along with other beneficial chemical compounds, to the genitalia, which is important for fertility and important during intercourse.