As he was dressing for a date with Rebecca, Mike Greeley, 28, a Boston real-estate broker, passed over the monochromatic suits and chambray shirts and chose a sweat-wicking top and sneakers. It wasn't an attempt at a casual look gone too far; he was meeting his crush for spin class. "I work 60-hour weeks, so it was a way to see her on weekends," he says. "But we were sweaty and our guards were down, so we really got to know each other."

Like Greeley, Dan Nainan, 32, a New York City comedian, began fitness dating out of practicality. "I travel a lot, and it's efficient to hang out while exercising," he says. Nainan chooses outdoor cycling for early dates. "It's more fun than a formal meal and saves time—any woman who says no probably isn't a good match."

These men are part of a new mating ritual: exercising together. Parks, gyms, and fitness studios are filled with couples putting their raw selves up for view. Celebrities are embracing workout rendezvous too—Jake Gyllenhaal was recently spotted emerging from Barry's Bootcamp with new girlfriend Alyssa Miller. It's now a staple paparazzo shot—although not officially dating, Ashley Greene and actor Jamie Campbell Bower were snapped departing a gym together in Studio City, California. This may be the best advance in courtship since alcohol (another oft-used guard-lowerer). If you're considering hooking up, and eventually coupling up, nibbling entrées won't reveal as much about the other person as a round of burpees might.

Ariane Hundt has noticed certain characteristics in the exercise daters who attend her Brooklyn Bridge Boot Camp. "They're often comfortable in their skin, in their thirties, and looking for a partner," she says. She adds that this is not the terrain of the preening, egocentric gym rat eager to show off his heaving muscles. "It's not the overconfident jocks," Hundt says. "That doesn't work, because most women don't care if you're an impressive exerciser. They care about compatibility."

How much you bench may not be a factor, but where you do it might—since like restaurants and shoes, the facility you choose indicates taste. "The studio scene lends itself to the trend," says Cate Brinch, owner of Recycle Studio spinning clubs in Boston, who has seen a sharp rise in workout dates. Boutique gyms imply status (a sign that you can afford pricey classes and hang with tough instructors), and, Brinch says, "now you can invite someone to your yoga or cycling class without a membership. It's a more social environment."

While they're informal, exercise-based outings can also be a way to connect. Greeley soon joined Rebecca on her marathon-training runs, too, fast-forwarding the relationship. "It was an opportunity to be supportive about something important but not serious," he says. "Helping her through a 15-miler became a blueprint for the future." The couple that sweats together stays together—or stays fit enough to lure future lovers.

• • •

The Gym Date—Perfected

Sexercise Dos and Don'ts

Do aim for a 45-minute activity. A 60- or 90-minute session will leave you too sweaty and tired and means less time for post-gym activities.

Don't talk through class. Banter about what you're doing and light joking is fine; save the getting-to-know-you conversation for the juice bar.

Do opt for an all-level class. "Skip sessions where you have to move to the same beat"—like dance-based classes or advanced yoga—"because you're not necessarily at the exact same fitness level," says Sara Haley, who teaches cardio blast at Equinox Santa Monica. Boot camps and cardio are safer bets.

Don't objectify your gym date. Compliment his or her appearance if you feel the urge, but without mentioning the butt-hugging shorts.

Do check your ego at the door. Show your date that you're fit, but don't show off.

Don't wear headphones. Period.

Do go dutch. You'll likely sign up and pay online ahead of time. Bring your date a bottle of water and a towel and cover the post-workout smoothie.

Don't shower and change after. "You're not trying to hide that you just worked out—and you'll look sloppy anyway," Brinch says. Bring a clean shirt and deodorant.

Top Date-Friendly Workouts
The best fitness-fueled dates make both of you feel more comfortable by involving structured activities and other people, such as a class or intramural sports game—not "let's hit the weight room for an hour."

If you're . . .
Outdoorsy
Try: cycling, rollerblading, hiking, rock climbing.

A Gym Rat
Try: spinning, bootcamp, yoga.

Sporty
Try: kickball, soccer, beach volleyball.

Aqua Man
Try: kayaking, water aerobics, masters swimming.

Where to Go Afterwards
1. Nowhere. Not feeling the love? Say "Hey, thanks for the great workout."
2. The smoothie shop. Chitchat for a time-limited half hour.
3. The movies. Safe, cuddly, good if you're tired.
4. A healthy restaurant. See if the conversation flows over quinoa.
5. Your place. Who says the sweating is over?