With 15 half-marathons and two marathons under her belt, D.C. resident Melissa Murphy is now training for her next race with the help of a few fitness apps on her smartphone.
"There's a visual map of where I've run.," she explains. "And I have mile-by-mile data of how fast I've been running."
However, there’s a chance someone else may be watching her journey.
Evidon, a privacy technology company, found that many popular fitness and health apps actually share data with other companies.
"It wouldn't stop me, but I would want to make sure I knew how they could use my data and if they could or could not sell it to a third party," says Murphy.
Cora Tun Han with the Federal Trade Commission says, "I think they might be surprised with the collection of information that's happening."
The Commission does warn that app providers need to let users know if someone is tracking their run, blood pressure, or even their pregnancy.
"We do look at whether or not apps are honoring what they say in their privacy policies," says Han.