Mindshare, the global media agency under WPP's GroupM, is placing a big bet on wearables with a new unit, Life+, devoted to funneling advertising dollars into futuristic products. The unit will experiment with fitness trackers and sensors, smartwatches and augmented reality devices, like Google Glass.

Norm Johnston, chief digital officer of Mindshare Worldwide, likened wearable technology to a third wave in digital advertising -- after Internet display and mobile. But he stressed the devices would require "more native content and storytelling" than traditional advertising. "They're quite intimate and the data shared is very sensitive," he said. "It's not about just slapping up ads."

Jeff Malmad, Mindshare's managing director of mobile, will lead the unit, which will include two additional staffers in New York and two in London. That number could double by next year, the company said. With Life+, Mindshare is partnering with MapMyFitness, the health and fitness-tracking app owned by Under Armour.

Samsung recently tied up with MapMyFitness for a new device, the Galaxy S5 Sport, with Sprint. Apple and Google have also moved aggressively into health-data tracking technology; as have AT&T and Verizon. Research group IDC estimates the wearable computing market will ship 19 million units this year and grow more than fivefold by 2018.

Still, wearables are not yet mainstream devices -- or mainstream channels for brand dollars. Life+ is Mindshare's bid to get ahead of the curve if that changes. "We'd rather navigate those issues for our clients first than last, or second or third," Mr. Johnston said.