Dr. Manny gave Rachael the skinny on some popular food myths, and now the author of The Checklist is back to challenge some myths about a topic everyone is curious about (but too embarrassed to discuss) - sex!

Myth: Women hit their sexual peak in their 30s.

Dr. Manny: "Women really peak when they're 35, 40, 45 - that's really when the peak of sexual drive begins."

Myth: Single women have more sex than married women.

Dr. Manny: "Absolutely not. Married couples have more sex than single people. Number one, they're together -- they see each other constantly. They have developed a pattern of romance. Single people have to go out and meet somebody and go through the whole craziness of dating. Married people have more sex, just because you're together all the time and you gotta do something with your free time."

Myth: Sex typically lasts 15-20 minutes.

Dr. Manny: "Most people could have done it during the commercial break! Three to 10 minutes on average, believe it or not. Some people say two hours, eight hours - give me a break!"

Myth: During pregnancy, sex brings on labor.

Dr. Manny: "This is a very common question that a lot of pregant woman always have on their minds: Can I have sex while I'm pregnant? The answer is yes - sex got you pregnant and you can have sex while you are pregnant. There are very few times when you cannot have intercourse during pregnancy. For the most part, yes, you can, but you have to be careful. And sometimes pregnancy can even bring a little extra libido into the relationship."

Myth: Bicycle riding can lower your fertility.

Dr. Manny: "If you are like crazy riding bicycles (especially men) all the time and you don't pay attention to the whole exercise routine, you can lower your fertility rates a little bit. But for the most part, the best thing for sex is having a healthy heart and being in shape and there's nothing like riding a bicycle. I would say that it's OK to ride a bicycle and the data doesn't really show any big difference one way or another."

Myth: As you age, "the Big O" gets weaker.

Dr. Manny: "That's not true. Sex doesn't really go down with age. Age has nothing to do with it. What has a lot to do with it is our energy, our hormones. It's like good wine. If you take good wine and you save it and you keep it in the right place, it's going to age gracefully. The same thing for sex as we get older. There are couples who are in their 60s who are burning the candle on both ends (if you know what I mean) and they have all the energy, they take care of themselves, they eat right, they exercise, and of course, their sex drive continues to be just as beautiful as when they were in their 30s."