Work out, get on scale...tell your friends?

Social-sharing crazes, it seems, have no end. We tweet our grocery lists, share our charitable donations on Facebook, and use Foursquare to chronicle our journeys from home to Starbucks to the office. Now, it seems, it's all about broadcasting your well-being.

So when I decided to step up my recreational distance-running habit into actual race training a few months ago, of course I started exploring the outstanding array of mobile apps, fitness-tracking gadgets, and community sites out there and the experiences of people who have been using the social Web as an outlet for their training goals. What I learned: data tracking has got me hooked, but I'm not into the public sharing and don't see that changing any time soon.

It doesn't really make sense. Why, when I'm perfectly comfortable telling my Twitter followers that I've just become the Foursquare mayor of my neighborhood coffee shop (major personal victory, by the way), do I not want to post the results of this morning's six-mile run?

Fitness experts, after all, say that social media can legitimately help people stick to their goals. "There is something about stating an intention aloud or writing it down, and especially about making it public, that typically promotes accountability," Stacey Rosenfeld, sports psychologist for the New York City Triathlon, told me via e-mail. "For those who are looking to improve health or fitness, posting goals on public sites may also provide them with a sense of community as they work toward common goals."

I might just be stubborn. For years, I was viciously low-tech about running, often not even wearing a watch. A sunny afternoon, a good classic-rock playlist on an old-school iPod, and a rough estimation of mileage along some expanse of urban waterfront or city park was about all I needed. A few months ago I was seduced by the charts and graphs promised by geeky fitness data services, and workouts now render me embarrassingly part-robot.

On my wrist there's a Garmin ForeRunner 110 GPS watch to tell me exactly how fast I've been running and for how long; there's a heart rate monitor belted around my midsection; and clipped onto my running shorts is a Fitbit, an obsessive little activity tracker that stays on just about 24/7 (it doesn't go into the shower) and uses a Nintendo Wii-like sensor to track movement and translate more or less everything I do into vibrant, primary-colored charts and graphs.

The $99 Fitbit is limited but addictive regardless. If mountain ranges teach us pieces of the Earth's history, so do these cartoonish peaks and valleys tell my own quotidian chronicles: here, I was reaching an arm out of bed to smack the snooze button on my alarm clock. There, that magenta spike happened when I was sprinting to catch the subway. That little fuzz of turquoise-hued low activity was, in fact, grocery shopping.

"We call it 'phantom Fitbit syndrome,' where if someone leaves their house without their Fitbit they kind of feel lost or have this urgent desire to run back to the house to grab it because they feel some part of their body's missing," Fitbit co-founder James Park told me regarding the device's addictiveness. "If they forget to wear it for like 10 or 15 minutes and start to miss some of their data throughout the day, people contact customer support and say they want the entire day wiped out because it's not right."

The company has run into a bit of bad PR from product back-orders and an early software glitch that had to be quickly resolved. But it's been a hit, Park said. Fitbit just launched a paid subscription program that supplements its free data tracking with more detailed analytics and an automated "personal trainer," and on the way is a developer API so that applications can be built on top of the product. (Park used the example of a hypothetical game in which Fitbit users' progress would be applied to track how far they've "run" from a hungry horde of virtual zombies.)

It was with Fitbit that I got tuned into the idea of sharing the entire active lifestyle--not just, say, "Hey, I ran a 5K race in 23 minutes"--with the Web at large. The device-and-Web-community start-up, which launched last fall to much fanfare, operates extensive forums as well as member profiles that can display individual users' Fitbit habits. Weekly updates can also be auto-shared with Facebook and Twitter, something that Park says 10 percent of active users do.

And the amount of information that can potentially be shared publicly, updated practically in real time, is astounding, ranging from the Fitbit-tracked steps taken and calorie burn while walking and running, to manually entered foods consumed, other physical activities, and weight. It can also post your sleep habits, as the Fitbit tracks those too while in "sleep mode." My reaction: no way is anybody seeing that.

Of course, none of this is a new concept. Digital fitness tracking sprinted into the mainstream about four years ago when Apple and Nike partnered on the original Nike+ product suite, which connected a running shoe with a built-in sensor to new software for the iPod Nano and tracked time, distance, pace, and calorie burn. Within a year of its Lance Armstrong-endorsed debut, Nike+ had expanded to include downloadable Apple dashboard widgets and a community Web site where members could share their goals and progress.

Now, there are Facebook apps like RunLogger (intimidatingly dominated by high school cross-country jocks), and mobile software like iPhone apps Calorie Tracker, Fitness Log, and Walkmeter, and the Android app BuddyRunner. Then there are Nike+ hardware rivals, like Adidas' MiCoach and Philips' DirectLife. The Withings scale can tweet your weight and body mass index (BMI) automatically.

There are, also, Web communities from Livestrong.com (also Armstrong-endorsed) to fitness support community MyFitnessPal to the more hard-core DailyMile to mainstay SparkPeople, which made a foray into weight-loss-centric social networking a few months before the Nike+ system's debut.

"My wife and I were trying to lose weight for our wedding, and I was looking around--I'm kind of a computer nerd, and I went to the web to try to find some people to help me do it, and I just wasn't happy with it," said Mike Lee, founder of MyFitnessPal, which encourages members to log their workouts and food intake and then share them via Facebook and Twitter in addition to the site's community of users. "I just thought I could do it better."

Talking to people like Lee, I still felt that there was an uneasy undertone to it all. Sharing fitness goals frequently starts to veer into weight loss, something that can evoke the ugly history of online pro-anorexia support groups. Anonymous or semi-anonymous Internet commenting can spawn nastiness, especially if it's related to weight, appearance, or eating habits. Not to mention the fact that health communities on the Web may have problems with self-diagnosis in which people who really ought to be seeing a nutritionist or physical therapist are attempting to tackle their problems head-on.

The executives of companies that promote sharing fitness goals are far from unaware of these sensitivities. Fitbit's Park said that while the company has not encountered any unfortunate behavior in its user forums, that they're considering bringing nutritionists or other health professionals on board to interact with the community and offer more seasoned advice.

"You have complete control over what you share, both within the site as well as on Facebook or Twitter. You don't have to share anything if you don't want to," MyFitnessPal's Lee assured me. "In terms of what we share, we really try to focus on the positive. For instance, we won't post your actual weight, we'll just post that you've lost two pounds or four pounds or whatever it is that you've lost."

Sports psychologist Rosenfeld said that there is potential for harassment and cruelty in online fitness communities, but she seemed to be more concerned about people getting carried away with goals and heightened expectations. "Someone who starts off weighing herself once a week and recording that could turn into someone who weighs herself daily, then multiple times daily," she told me. "Someone who tries to keep a rough calorie estimate could go overboard and start weighing individual food items and restricting many foods. A person who is tired or injured may feel the pressure to hit the gym again because he said he would."

There is, of course, a middle ground. Bruce McClary, a Seattle resident and avid runner who has been using the BuddyRunner Android app for about a year now, posts his running progress to Facebook and Twitter. But his Facebook account is friends-only, and his Twitter tweets are "protected."

"I don't know if I would do this if it were public," McClary told me via phone. But he said making his running progress accessible to the people he knows via Facebook and Twitter makes him feel accountable regardless. "There's no more 'big fish' story where you go fishing and you say, 'This 20-pound bass! I hooked it, but it got away!' Not that I would exaggerate about running, but it does keep me in check."

He also declines to tell his friends what his goals are, and says it saves him from undue stress.

"If I said I was training for an ultramarathon and then just made it to a regular marathon, it could be demotivating to me personally and could draw a lot of criticism that I don't want," McClary said.

I think just about anyone would deem a "regular" marathon to be worthy of celebration, but McClary has a point. Some people--not everyone--are happier bucking the share-everything trend and keeping a few things to themselves. And thankfully, as I've realized through the numbers that Garmin and Fitbit spit back to me daily, the ominous charts and graphs add up to an ample amount of accountability for me. I don't need to take the next step and share it with the world.

And, hey, maybe on some level I'm insecure about whether I run fast enough to be comfortable posting it on Twitter, or maybe it's a case of wondering whether my Facebook friends really want or need to know this stuff. Even in this day and age, the "too much information" defense has some legs.