When UnitedHealthcare launched a wellness program two years ago in hopes of getting people walking throughout the day, the nation’s largest health insurer issued to participants its own wearable devices for counting steps.

It turns out that lots of people have allegiance to activity-tracking devices from particular manufacturers, so the health insurer has switched to a “bring your own device” model for a program that’s provided $19 million in rewards thus far.

At the start of 2017, Minnetonka-based UnitedHealthcare announced that program participants could use certain devices from FitBit, the San Francisco-based company whose products have become synonymous with the trend of people wearing activity trackers on their wrists.

This month, the health insurer added devices from Samsung and Garmin, and expects the lineup will continue to grow.

“People have their own trust, relationships and frankly affinities to specific brands,” said Paul Sterling, a vice president of emerging products for UnitedHealthcare. “We want to support that, and so we want to provide choice in terms of the device that people can use with the program.”

A number of health insurers are running with the fitness tracker concept.

Last year, Connecticut-based Aetna rolled out a wellness program that incorporates the Apple Watch fitness tracker for employees and customers.

Bloomington-based HealthPartners and Minnetonka-based Medica say they also have programs that let employers provide incentives for walking that’s tracked by wearable devices.

While FitBit has been the biggest player in what analysts call the “U.S. connected fitness tracker market,” competition is heating up with offerings from Apple, Nike, Garmin and Google, wrote John Kernan, an analyst with Cowen, in an August note to investors.

The activity comes even as the jury is still out on the health benefits of such programs. Researchers published a study last year in the Journal of the American Medical Association that followed 450 young adults over 24 months and found those who used a wearable technology device in addition to standard interventions actually saw less weight loss than study participants who didn’t use the devices.

“Devices that monitor and provide feedback on physical activity may not offer an advantage over standard behavioral weight loss approaches,” the study concluded.

Even so, a growing number of employers and insurers seem swayed by the idea that workers who get up and walk around will be healthier. In its annual surveys, the benefit consulting firm Mercer found that 24 percent of large employers in 2015 were utilizing technology-based resources such as wearables and apps to encourage activity — a share that increased to 31 percent last year.

“I can tell you that from my own client work there is an increase in interest in the use of technology to help promote overall well-being programs,” said Ray Balcazar, a Mercer consultant in Minneapolis, via e-mail. “Many independent vendors including carriers such as [UnitedHealthcare] are now embedding these programs into their core solutions.”

After first piloting its program in 2015, UnitedHealthcare announced early last year a broader rollout in which health plan enrollees could use fitness tracking devices and have a shot at earning up to $1,460 over the course of a year for meeting certain activity goals. The collaboration with San Diego-based Qualcomm was expanded this year to employer groups in most states, said Sterling, the UnitedHealthcare official.

Participants can each earn up to $4 per day in their health reimbursement account (HRA) for hitting all three distinct targets. If they take 500 steps within 7 minutes, six times per day, the health plan enrollee earns $1.50. The enrollee earns another $1.25 for walking 3,000 steps within a 30-minute period. Finally, walking a total of 10,000 steps in a day brings another $1.25.

UnitedHealthcare describes the three walking goals, respectively, as frequency, intensity and tenacity. FitBit, Garmin and Samsung have tailored their wearable fitness trackers to track the insurance company’s three goals, Sterling said.

Participants thus far have had the most difficulty hitting the intensity goal, he said, since it often requires people to consciously set aside 30 minutes for hitting the 3,000-step mark. During the workweek, participants tend to have better luck hitting the frequency goal, he added, and better luck during the weekends hitting the 10,000-step mark.

The incentive dollars are slightly smaller when employers provide funds in an employee health savings account, Sterling said, rather than an HRA.

Sterling said more 200,000 individuals across thousands of employer groups have participated in the UnitedHealthcare fitness program. The company says participants, collectively, have walked more than 130 billion steps.