Every year, around the time between Thanksgiving and Christmas, online reviews of wearable fitness trackers proliferate. Understandably so, given that these devices are prime holiday gifts, and because a growing number of people 50 and up are dedicated consumers of the data that fitness trackers provide.

Healthy aging, and all that.

This week, I decided to take a closer look not at the reviews of the functions that popular fitness trackers include — information easily gleaned from any generic online review — but rather at what the device makers do with all the personal health data that we give them, pretty much for free.

The short answer: it depends wildly on which company gets your money.

I compared 11 devices across metrics that product reviews tend to overlook — data ownership, export rights, subscription requirements, and the legal jurisdiction governing your privacy. What emerged from my reporting is a market divided into camps with fundamentally different ideas about who that heart rate data belongs to once it leaves your wrist.

Apple, Oura and Garmin occupy one end of the privacy spectrum. All three have public policies that say users own their data, that offer robust export in standard formats and that operate under U.S. or European privacy laws that carry actual weight.

If you decide next year to switch devices or just want a complete record of your last five years of sleep measurements, you can have it.

Xiaomi and Huawei sit at the other end. Both offer capable hardware at seductive prices — $40 for a Xiaomi Band 9, $59 for a Huawei Band 9. Both provide what the fine print calls "very limited" export options. The Mozilla Foundation, which audits consumer product privacy, awarded Xiaomi its worst rating. Huawei carries additional baggage: Chinese law mandates that companies provide data access to government authorities upon request.

No corporate privacy policy overrides that.

Fitbit occupies an uneasy middle ground. Google acquired the company in 2021, folding your resting heart rate into the same data ecosystem that tracks your searches, reads your email and follows your movements. The Federal Trade Commission has kept the arrangement under ongoing scrutiny. Whether that bothers you depends on your comfort level with a single company assembling such a thorough profile of what you do, where you do it and with whom.

Then there's the subscription question, which affects your wallet more directly.

Whoop makes an excellent tracker favored by professional athletes. It also charges $239 annually and won't display a single data point without payment. The hardware comes "free" — you're not buying a device, you're renting permanent access to your own pulse. Cancel after three years and you've spent $717 to own, essentially, nothing.

Your historical health data stays, profitably, on Whoop's servers.

Apple and Garmin work differently. Pay once for the hardware, and everything functions without further tribute. Both offer optional premium subscriptions — guided workouts, coaching features — but the measurements remain yours either way. An Apple Watch Series 10 costs $399, full stop. A Garmin Vivoactive runs $299.

The Oura ring, which costs $349 to $499, requires a $70 annual subscription that's technically optional but practically necessary for the analysis that justifies the purchase. Still, the data exports cleanly and the company operates under Finnish jurisdiction, which means EU privacy protections apply.

For the budget-conscious, RingConn offers a ring at $199-$299 with no subscription and includes sleep apnea monitoring — though it's headquartered in Shenzhen, so the usual Chinese jurisdiction caveats apply.

The accuracy differences between these devices exist but matter less than marketing suggests. Apple Watch carries the most peer-reviewed validation of any consumer wearable. Oura shows about 79% agreement with clinical sleep studies — which is useful, if imperfect. The budget options hover around 85-95% accuracy at rest, degrading during exercise. All of them will tell you if your resting heart rate is trending in the wrong direction.

What the accuracy reviews miss is that you're building a longitudinal record of your own biology. Five years of daily measurements adds up to something unprecedented — a continuous portrait of how your particular body ages.

That portrait has value beyond your own curiosity. Insurers would find it interesting. So would employers, researchers and the data brokers who monetize our digital exhaust.

Before you buy, ask the questions the holiday gift guides won't: Can you export everything? Who owns it? What's the real cost over three years?

The body you've spent decades maintaining (more or less) is now generating data worth protecting. If you don't, the company that made your fitness band, watch or ring certainly will.

To find out more about Paul Von Zielbauer and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.

Photo credit: Andres Urena at Unsplash