Use it or lose it: Yes, it's true

Urology clinics have a saying: "Erections make erections."

In other words, sex is not unlike sports. If you want to be a good tennis player, play lots of tennis; if you want to be a good lover, make lots of love.

This maxim springs more from anecdotal observations than from scientific studies: Men who have erection problems tend not to have much sex, urologists noticed. And those who don't, have plenty. Then again, anyone with a passing knowledge of the birds and the bees might have guessed as much.

So, which happens first in the use-it-or-lose-it Olympics? In sports as in sex, we like to do what we're good at doing. Perhaps when some men find that their previous prowess -- be it at backhands or erections -- isn't what it used to be, they start sitting out more and more games.

A new study following nearly 1,000 Finns, published July in the American Journal of Medicine, might help answer this question.

Researchers with the Tampere Male Urological Study in Finland first sent questionnaires to men ages 50 to 75, inquiring as to the quality of their erections and the frequency of their intercourse. (The researchers didn't ask about masturbation.) Men who reported no major problems were included in the study.

Next, the researchers sat back and waited five years. Then they tracked down the men again and asked about their general health -- including any erection problems that had developed since the first questionnaire.

Results support the use-it-or-lose-it hunch. Having sex once a week halved men's chances of developing erectile dysfunction, compared to a less-than-once-a-week schedule. (The study also hinted that the more often men had sex, the better they fared.) In their analyses, the researchers made sure that other health factors -- such as heart disease, diabetes, obesity and depression -- did not explain the differences among men.

So what's going on here? Why does having more sex keep the male organ in trim instead of wearing it out? The likely elixir is oxygen, says study lead author Dr. Juha Koskimaki, consulting urologist at Tampere University Hospital -- specifically, oxygen molecules summoned to particular parts of the penis by erections.

When a man is sexually aroused -- whether by a touch to the penis or a favorite Jenna Jameson flick -- nerves stretching from the brain to the base of the spine and throughout the penis kick into action, triggering chemical and electrical signals.