It's true of your brain and mental abilities and your muscles for sure. Well, it's also true in urology - "Erections make erections." Want to be a good cook? Practice. Want to be a good lover? Practice. Urological experts have relied on some anecdotal observations to take note of the fact that alot of men who have erection problems - tend to not have alot of sex.
So if there is "failure to achieve erection" during an intimate moment, the guy typically begins to get a little uptight about the next time. So maybe he delays the next time. And maybe because he delays the next time - it happens again. So now he really, really delays the next time. And ED - is now a reality.
A study that observed 1000 men from Finland gathered information from questionnaires sent to these men. They were asked about quality of erections, frequency of sex (they were not asked about masturbation). Researchers logged the information and waited 5 years and then re-visited the men with a follow up questionnaire about their health and any erection problems that had developed in the 5 years. The "use-it-or-lose-it" theory was supported. And the study stats and results even hinted that the more sex these men had - the better they fared.
One theory is that the oxygenation that occurs in the blood vessels as they enlarge to accomodate and fuel the erection, also helps to keep the penile tissue healthy, active and ready to perform the enlargement and stiffening action that occurs during an erection. Researchers are now even wondering if the unconscious erections that occur during sleep are nature's way of keeping a regular supply of oxygen flowing to the penis. So think of sex and natural erections as a way to "keep you happy - your woman happy - but most of all, to keep your sexual organ in full, working condition." Now you might ask - well, why doesn't** masturbation** achieve the same result?? Researchers are hypothesizing that oxygenation needs to last for a certain time elapsed period. Sexual intercourse and the erection itself usually lasts longer than masturbation and its erection. So they are assuming insuffucient oxygenation may happen during masturbation. Experts also concede that "some people may just be better wired from birth to have better erections for longer periods of time."
Trust me - there will be more research in this area. For the moment, use it or lose it, needs to be the operative assumption for most men who want to avoid one cause of ED.