Pelvic floor exercise, also known as Kegel exercise (/ˈkeɪɡəl/), consists of repeatedly contracting and relaxing the muscles that form part of the pelvic floor, now sometimes colloquially referred to as the "Kegel muscles". Several tools exist to help with these exercises, although various studies debate the relative effectiveness of different tools versus traditional exercises. Exercises are usually done to reduce urinary incontinence (especially after childbirth) and reduce premature ejaculatory occurrences in men, as well as to increase the size and intensity of erections. They were first described in 1948 by Arnold Kegel.