Meredith, a 19-year-old psychology student from New York, remembers that "weird tingly feeling" as a child, doing workouts for gymnastics.
She called it the "candlestick," the exercise where she would raise and lower her legs, tightening her lower abdominal muscles.
Now, a new study suggests some women don't need a lover or sexual fantasy to experience sexual pleasure or even orgasm. Exercise can do the trick.
For years, fitness and women's magazines have touted the apocryphal "coregasm," but now researchers say that hundreds of women are getting the unintended benefits of those tummy crunches.
Knowing the orgasm feeling was a bonus for Meredith, once she became sexually active, she said. And now, she openly talks about her coregasm.
"Being a part of so many clubs in college and get-to-know-you games, it's an ice breaker," she said.
An estimated 45 percent of the women who responded to the researchers' online request for women who had either exercise-induced orgasm (EIO) or exercise-induced sexual pleasure (EISP) said their first experience was during abdominal exercises, followed by weight lifting (26.5 percent), yoga (20 percent), bicycling (15.8 percent), running (13.2 percent) and walking/hiking (9.6 percent).
"For me as a scientist, that's a stripped down version of orgasm, without sex or a partner," said co-author Debby Herbenick, co-director of the Center for Sexual Health Promotion and sexual health educator at the Kinsey Institute at Indiana University.
Any exercise that involves the core muscles seems to trigger that sense of pleasure -- chin-ups, climbing ropes and especially the "captain's chair," a rack with padded arm rests that allows the legs to hang free before lifting the knees to the chest.
A handful of women said they even had sexual feelings while mopping or walking.
From a physiological standpoint, "coregasm" makes sense, according to fitness experts. In both exercise and sex, the heart rate and breathing are faster and there is increased blood flow.
The study was published in a special issue of the peer-reviewed journal, Sexual and Relationship Therapy. Herbenick includes some of the experiences in her new book, "Sex Made Easy," due out in April.
"I was biking up a hill," she quotes one 41-year-old. "I had to really grind into the pedals. This must have caused me to rub on the seat in just the right away. I thought I was starting to cramp, but soon realized it felt great. [I] thought I should stop, but chose not to!
"I [had an orgasm] for the very first time shortly after that!" she said. "I never admitted to what had actually happened and I have tried to replicate it ever since -- with no luck!"
Another woman, 23, told Herbenick: "If I engage my lower stomach muscles -- the ones below my navel-- I get a sharp increase in pleasure, perhaps leading to orgasm. This is particularly true if I sit in a straddle position and reach forward. Also, if I lie on my back and stretch one of my legs up, pulling it towards me, I'll probably orgasm after a minute or two."
Herbenick, who is also an advice columnist, said this "exploratory" study is a first step to learning more about the "physical processes" of sexual pleasure.
"Exercise-induced orgasm is something we really know nothing about -- not scientifically," she said. "[Sexologist Alfred] Kinsey mentioned it in his ['Sexual Behavior in the Human Female'] book in 1953, and it sort of got left there."