Fitness trackers provides tons of information, but probably the most valuable part of that information is that it's real time. It can tell google information about your routine even when you don't have your phone on you (wake up and leave your phone on the nightstand while you get around? Now Google knows you're not asleep.)

I haven't had a Fitbit in years, so I'm sure some have GPS, which would increase the footprint of GPS tracking for runners that don't run with their phone (even if that not many), then you're getting ads about healthy food options near the start/stop point of your trail.

It could tell Google if you've been having trouble sleeping, then you're getting sleep aid or sleep study or high end mattress ads. I'm sure the fitbit can detect certain workout routines based on physical movement, and can cater ads to users based on whether they're weight trainers or endurance trainers as well as skill level.

I think there is a ton of high value information that can be gathered from a Fitbit for Google.

Well... what else does Fitbit's cloud store? How often you exercise? Where you do it? What sorts of exercise? Check out these running shorts, keep cool in the summer! Carbon fibre kayak paddles are on sale!

Or, when it's noticed a lull, and kmows you're influencable: Hire this personal trainer to get you back exercising!

Highly targetted ads are not my concern here, they may even be welcome.

Using heartrate, activity levels, mobilty can probably infer a broad picture of someones health, which of course, would be very valuable to health insurance/life assurance companies.

With this level of privatised surveilance, I'll stick with my mechanical automatic watch thanks.

With sufficient data you could find out much more than that. Your heart rate dropped around 8:20 and spiked shortly after at 8:25? The same happened to 3 million other customers, looks like you are also enjoying the Game of Thrones premiere on HBO.

Located in Hong Kong, elevated heart rate in the evening, spikes match tweets about police activity against protesters? Be prepared to be visited by the authorities.

does google sell data or attention? the whole point of google/facebook ad networks is that THEY keep the data hidden and let you use it as a filter, without being able to see it. they would lose their value if their data was for sale.

google would sell "attention time to people whos heart rate spiked during the world series" but not tell the customers who those people were. you would be outing yourself if you click the ad.

Yes hiring personal trainer ads is the market Google was so desperately after all these years

Global health club market is 87 billion based on, err, googling. How much would that market benefit from highly targeted advertising? Only Google knows that: but you can take a guess from the money they paid for Fitbit. Someone needs to stop them because they can sell any business that benefits from target advertising better than its current owners. The purchase itself is Monopoly abuse.

It’s not just biometrics — now they’ll now where you are. Lots of people who don’t already have android phones will buy these (or carry them when not carrying their androids).

So google will know what stores you’re near, what people you’re near, and for how long.

Google knew where you were long before fitbit. It's called Directions API.

I use Apple maps, and I only use navigation when traveling long distances.

Actually there is a ton of money in the health sector going digital. The more niche are virtual trials and compliance, but it represents 200 billions to pharma and government in the US alone. The more advertisement-related opportunities would be the one you can sell to drug stores and insurance companies. While Google maybe the king of ads, and would benefit from knowing what happens to you when you shop at target online vs in-store, Alphabet is involved in so many health, personalized, and direct-to-consummer related projects, that you don't even have to be creative to think about how they can use it.