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Comment by science4sail | Hacker News Reader

> U.S. Space Force leadership says the approach will prioritize the general wellness of service members beyond just one physical assessment each year. The annual tests have spurred eating disorder symptoms and other unhealthy behaviors in some military members.

It seems like one of the driving reasons for the change is a concern about people gaming the annual test. Couldn't fitness trackers also be gamed? For example, someone could put a pedometer into a motorized cradle to fake walking/running.

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Fitness trackers can measure more than just steps. I'm assuming (hoping maybe) they'll go by data like active/resting heartbeat rate and similar things, instead of just distance/steps.

Yeah. Step counting is bogus. Heart rate counting is much better but it's still flawed--it can end up reading repetitive arm movement as your heart rate and I've also seen cold conditions cause a substantial under-read.

It didn't surprise me that my wife's Fitbit could easily overcount 10,000 steps/day but I was really puzzled by heart rates as high as 180 (which is way above acceptable max given her age) until I found out about the problem of reading motion as heartbeat. I at least partially understood the evening my Garmin was showing a heart rate around 80 when 120 would have been more like it--it was cold but I didn't have far to go and I didn't consider stopping to layer up and killing my night vision in the process to be worth it. (I had enough moonlight that my headlamp was still in my pack, but I would have had to use it to ensure I didn't drop anything and that would have meant being annoyed by all the bugs that would keep flitting around.)

Actually max heart rate has very little relationship to age, at least for people who are in decent condition. If you're thinking about the infamous "220 - Age" formula, be aware that it's bogus and not well supported by actual data. There is a huge variance in max heart rates across the population. For example, that formula underestimates mine by 27 bpm. So a heart rate of 180 could be plausible for your wife at a high exertion level.

Optical heart rate sensors on the latest Garmin watches are usually pretty accurate. But they can give false readings if the band is too lose or the sensor is dirty. For any real workout or fitness test it's best to use a separate wireless heart rate strap paired to the watch.

I don't understand the mechanics of how my Garmin was fooled that evening but it definitely corresponds to the period that I was feeling cold.

As for 180 being possible for my wife--nope. We aren't youngsters and she was carrying on a conversation at the time. It was reading her arm movement, not her heart. I got myself a separate heart rate strap but Fitbit doesn't support them and she's just wearing it for the bonus the insurance company gives. (Which is set to such a ridiculously low threshold that you would have to be awfully sedentary to not reach it--in practice it translates to wear a fitness tracker, get $10/month.)

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