> The perineal muscles are involved in ejaculation when they are involuntarily contracted. The ischiocavernosus muscle is responsible for male erection, and the bulbocavernosus muscle is responsible for ejaculation. By actively contracting the perineal muscles with Kegel exercises regularly, strength and control of these muscles increase, possibly aiding in the avoidance of premature ejaculation.

https://en.wikipedia.org/wiki/Kegel_exercise