It's not every personal trainer who inspires a client to write poetry in her honor. But after a few weeks of training with doe-eyed Maya, Glen Raphael couldn't help but extol her virtues in verse: "Sweet Maya never sleeps or even tires/I rarely get a sense that she perspires."

Posting such ardent poetry might be embarrassing -- if Maya could actually read it. But Maya is not a real person; she is a computer-simulated woman designed to be an ideal trainer. "She's my personal trainer," said Raphael, 38, a software engineer in San Francisco. "She just happens to live in my television."

Each time Raphael begins a workout, Maya asks how he's feeling and the next time, remembers whether he said upbeat or sluggish. She also nags if he misses a scheduled workout, asking, "Where were you yesterday?"

All it takes to get Maya to customize a personal exercise program is a personal computer or a video game console (PlayStation 2, Xbox or Xbox 360) and an additional $34.99 for the training game, "Yourself!Fitness."

Virtual trainers in such programs come to seem real to the people who use them not only because they are designed to be affable but also because, through the magic of computing, they can actually keep track of users' progress over months. Unlike fitness DVDs that show the same exercises day after day, virtual trainers can suggest ever-more-difficult workouts.

In just over a year, more than 100,000 copies of "Yourself!Fitness" have been sold, a drop in the bucket compared with the mammoth sales of traditional games. But at-home exercisers, out-of-shape novices and video game players who have tried the game say they enjoy combining exercise with a video game and that, with consistent use, it helps boost fitness. Some fitness experts warn that video coaching is a poor substitute for good one-on-one training. Still, for the price of a few sessions with a trainer at a gym, people can "hire" a cybertrainer who can meet them anytime they like and who is knowledgeable about fitness.

"Everybody needs feedback, and it's a heck of a lot cheaper than paying a trainer," said Doug Lowenstein, the president of the Entertainment Software Association.

Watching you, too

Personal training video games use various techniques to gauge a player's fitness. Before starting workouts with "Yourself!Fitness," players take a test that assesses their cardiovascular fitness, strength and flexibility. Then Maya suggests exercises -- including strength training, yoga, Pilates and step aerobics -- that target areas of weakness. Periodically, she asks the player to rate the difficulty of the drills, so she can intensify the workout if need be.

"The more input you give her, the more personalized the workout becomes," said Phineas Barnes, the chief executive of ResponDesign, which created the game.

"EyeToy Kinetic," a personal training game created by Sony Computer Entertainment Europe and Nike Motionworks, assesses a player's progress more directly. The "EyeToy" camera captures the player's movements and beams them on screen. The object of one game is to dodge some falling balls while hitting others with a deft punch or kick. If a player fails to evade the balls, a trainer offers advice.

"Kinetic" offers two trainers: either British Anna, whose coaching style is firm but polite, or her take-charge American counterpart, Matt. Both provide pointers and encouragement as they lead players through kickboxing, yoga, tai chi or cardiovascular drills like the ball drop game.

Kristen Dennis, who grew up playing old-fashioned combat games, said once she starts playing "Kinetic" she never quits, even if she tires. "I'm not going to stop because I know it's going to lower my score," said Dennis, 22, who is a research coordinator in the psychology department at Duke University in Durham. "I don't feel the same way about the elliptical."

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