These digital trainers know how to motivate

Sticking to exercise and weight-loss goals can be tough. But new computer-based products can help you along the road to fitness, offering steady electronic encouragement and suggestions.

Step on a sleek black scale from the French company Withings, for example, and you'll no longer need to keep a paper record of your progress; the scale will beam your weight numbers by Wi-Fi to your computer. From there, the stats can go directly to Twitter or to many other sites, so that your friends can read the bulletin and cheer you and your willpower to victory.

The scale, which sells for $159, has a processor and a built-in Wi-Fi connection so it can communicate with your home network. If you give the O.K., news of your weight loss travels from scale to computer to iPhone or iPad (using a free app from Withings), to your BlackBerry or, starting next month, to Android phones. The data can also be sent to supportive friends at fitness Web sites like RunKeeper or DailyBurn. Rah-rah! Fight those Twinkies!

For those in need of a personal electronic exercise coach, the Finnish company Suunto has a new series of watches that monitor your heart rate -- while also making you look stylish. I tried out the Model M4, which can create a snappy seven-day workout program and provide guidance and morale-boosting messages in crisp displays on the watch face. The watch, which sells for $169 on Amazon, has a simple, three-button interface; it receives its heart rate data from a transmitter cushioned in a soft black belt that is pulled snugly across the chest.

The M-series heart rate monitors are intended for beginners and fitness enthusiasts, not for elite athletes, said Ewa Pulkkinen, a product manager at Suunto.

"They are specifically for people who need motivation and inspiration to get up and keep going," she said.

(I am one of these people, and I welcomed the cheerful coaching that the watch provided, from its announcement of the "exercise day" before we began, through "next set" as we proceeded, to a final "Good workout!")

"The program tells you how long and how intense your workout should be," Ms. Pulkkinen said. It notifies wearers when to slow down or speed up so that their heart rates are within a recommended zone.

Polly Hopkins, a graphic designer in Park City, Utah, uses her new Suunto monitor as she hikes, mountain-bikes and runs -- and, afterward, as a regular watch. She likes the simplified controls. "Compared to other monitors I've had, this one is by far the easiest to use," she said.

Of course, any exercise guided by feedback from a heart rate monitor should be undertaken prudently, said Walter R. Thompson, a professor of kinesiology and health at Georgia State University in Atlanta. "Heart rate monitors can be incredible motivators," he said. "If your target is 150 beats per minute and you see you aren't quite there when you are exercising, a monitor is a terrific impetus." But maximum heart rate will vary from one person to the next. "You should check with a doctor first to get clearance for exercise," he said, and then consult with a certified trainer about a target heart rate range.

Technology may soon offer another tool for those struggling to stay trim and healthy: small robots that give diet advice. Dr. Caroline M. Apovian, an associate professor of medicine at the Boston University School of Medicine and the director of its center for nutrition and weight management, was adviser to a study to see whether people would accept a robot as a diet coach. A third of the patients in the study kept track of diet and exercise on a computer; a third by recording data in a log; and the remaining third by daily conversations with a robot designed by Cory D. Kidd, then a graduate student at the Massachusetts Institute of Technology and now a Ph.D. and the founder and C.E.O. of Intuitive Automata, a company that creates robots for use in health care.

The robot, which has a woman's voice and is about 15 inches high, makes eye contact with dieters by way of its built-in camera.

"THE test was not to see if the patients lost weight," Dr. Apovian said of the study, "but to see if they made a relationship with the robot." Typically, people enjoyed working with the robot and did not want to give it back, she said.

"One person named it; another put a hat on it," she said. "They treated her like a buddy."

Dr. Kidd said his robot would be on the market in about a year, priced at about $500.

Dr. Apovian said robots might one day help spell busy physicians. "I have patients on diets who come to see me weekly because they need to be accountable to someone," she said. "But I can't be there for everyone."