zThe ability to maintain an erection without ejaculating seems to vary with age. zKinsey found that males in their late teens or early twenties could hold an erection for up to an hour. This was reduced to 30 minutes in men from 45 to 50 years old. zMasters and Johnson, however, found the opposite; that is, older men take longer to gain an erection, but once this is achieved, they maintain an erection longer than younger men.