The number of people using smart wearables is expected to grow 9% next year, but among people age 55 and older, it will jump more than 15%, according to research firm eMarketer.

The reason is that wearable makers like Apple and Fitbit have been adding health monitoring features that appeal to older consumers. Apple added a fall detection app and an EKG monitor to the Apple Watch Series 4 this year, for example, while Fitbit is adding a feature to detect sleep apnea.

“Wearables like smartwatches are now coming equipped with additional health features, which are especially appealing to older Americans,” eMarketer forecasting analyst Cindy Liu noted in a report on Thursday.

Fitbit (FIT) could use a boost. Even after introducing its popular Versa watch in March Fitbit’s sales have dropped 10% in the first three quarters of the year and its shares have lost 12% in 2018. Competitor Garmin (GRMN), which is less reliant on wearables, has done better, seeing sales in its fitness and outdoor segments rise 16% in the first three quarters while its stock price gained 14%. Apple (AAPL) doesn’t provide much detail about watch sales, but has said its wearables revenue, which also includes headphones and earbuds, rose 50% in the third quarter.

Next year, overall growth in the number of people using wearables expected to slower next year for younger age groups. Among those age 18 to 44, wearables usage will increase nearly 7% next year, while the number of kids ages 12 to 17 wearing the devices will increase 9%, eMarketer said. Middle-aged adults are among the leaders in adoption, with usage increasing 13% for those age 45 to 54.

By the end of 2019, almost 61 million people, or one in five adult Internet users, will use a wearable device of any kind. Just over half will be using more expensive smartwatches, with the remainder mostly opting for much cheaper fitness tracking devices.

Because of advancements in wearable technology, more people are willing to buy smart devices. Over the next five years, more watches will connect on their own to wireless networks (rather than relying on a linked smartphone’s connection), control smart devices around the home, and monitor other kinds of health data.

A revamped microprocessor for smartwatches from Qualcomm (QCOM) that is out this year will also help some manufacturers produce thinner watches with longer lasting battery life, making them likely more appealing to consumers.