Fitness trackers are hot, hot, hot.

So Parks Associates‘ latest study tells us, with 60 million US households expected to own at least one by 2019 (hey, only 4 years away!) with global revenues exceeding $5 billion. Of that, smartwatches will constitute 100 million units. Given that only 7 million Android-based watches have been sold to date, and that the Apple Watch is projected to be about 10 million (2.3 million sold to date, according to ZDNet which glows away), that may actually be–achievable. POLITICO Morning eHealth also reported from their interview that about one-fifth of smartphone and tablet owners use a health app on a monthly basis, and 19 percent of smartphone owners find a “master” health app that aggregates data from other health apps appealing. Parks release.

In the UK, of Juniper Research’s top five smart wireless devices, three have a relationship to health, with the Apple and Google-TAG Heuer smartwatches on the high end and GOQii Fitness using their or anyone’s watch or fitness band to keep you on track for the price of their subscription. Less karma than when we saw them last June at CEWeek, more coaching. The apps will be the primary generator of revenue in fitness-band land, with hardware margins declining in the next few years. (Speaking of revenue, Juniper’s full study will set you back a tidy £3970.)