Who would make an ideal fitness partner? Perhaps someone who is supremely fit and could serve as an inspiration and role model? Or maybe someone with whom you feel equally matched so you could rise to meet challenges together?

With more people turning to the internet to help them improve their health and fitness, Damon Centola, an associate professor in the Annenberg School for Communication, led a group of researchers investigating how people sought out health partners in an online forum, reporting their findings in the journal Social Science and Medicine.

Working with an existing online fitness website, the researchers recruited 432 participants to be part of their new “Health Improvement Network.” All of the participants shared 10 pieces of information: their age, gender, ethnicity, body mass index (BMI), fitness level, diet preferences, goals for the program, and favorite exercise, as well as their average exercise minutes and intensity level.

The researcher divided the participants into six groups. Each participant was then randomly partnered with six “health contacts” in their group with whom they could exchange information. Over a five week period, the participants were given the opportunity to select new health contacts and drop existing ones. The only information they had to base their choice on was the set of 10 characteristics that the other members of the group had shared. Participants had no knowledge of who each other’s health contacts were, or whether there were any “highly connected” individuals. This allowed the study to reveal which characteristics participants would use to make their connections.  

Though the researchers thought that perhaps the group members would select health contacts who shared similar exercise routines or interests, or even contacts who were very fit and could perhaps serve as role models, they found that the participants did neither.

“Instead they chose contacts based on similar characteristics that would largely be observable in regular, offline face-to-face networks: age, gender, and BMI,” Centola says.

The participants’ tendency to “make ties to ‘the devil they know,’” the authors write, “may unintentionally limit their opportunities for finding health information from sources that they are not normally exposed to.”

The findings suggest that although people in online health programs are beckoned with the possibilities of meeting healthier people who can provide them with information about new kinds of exercises and better strategies for getting healthy, they self-select into networks that look very similar to the kinds of networks that people typically have offline: People with similar age, gender, and BMI profiles as themselves. Centola suggests that health programs can work around this human tendency by actively recommending “health buddies” based on characteristics that are hard to connect to offline, but easy to find online, such as people who are good motivational partners, or partners who prefer similar exercises, or are working to increase their endurance to similar levels. 

“Our findings suggest that the trick to an information-rich online community,” says Centola, “is to encourage new kinds of ties by reminding participants just how valuable these online relationships can be.”