Fitbit’s Bad Day: How it ended up with multiple optical HR lawsuits, and a 20% stock drop


For the San Francisco based firm Fitbit, yesterday was likely the mother of all bad roller-coasters.  They started off the morning at 7:30AM with a packed press room in the Las Vegas Mandalay Bay Convention Center with the launch of their newest product – the Fitbit Blaze ‘smart fitness watch’.

But within 30 minutes of the press event things started to unravel – when not one, but two totally unrelated lawsuits were filed and announced.  One a multi-state class action lawsuit alleging inaccurate optical HR sensors.  At virtually the exact same time that news broke, both mainstream and non-mainstream press alike panned the just announced Fitbit Blaze, causing significant investor concern which led to a selloff and nearly a 20% drop in stock price.  Or, ~$1.1 billion USD drop in market cap.  Yes, a bad day indeed.

The Fitbit Optical HR Sensor Accuracy Lawsuit


First up is a multi-state class action lawsuit that alleges that Fitbit’s optical HR sensor within the Fitbit Surge & Fitbit Charge HR products, is inaccurate at higher intensity levels.  The lawsuit claims:

“Far from “counting every beat,” the PurePulse Trackers do not and cannot consistently and accurately record wearers’ heart rates during the intense physical activity for which Fitbit expressly markets them.”

Now, this is obviously something that’s well within the ballpark of things I testedA lot.  And in fact, there’s definitely some truth to this, but not quite as much as the plaintiff’s want.  You’ll remember that I found that it was slower to react than I would have preferred, but eventually did catch-up – even in high intensity running.

Now, my guess is that the plaintiff’s will explore other exercise areas such as those in gyms that focus on wrist movements, an area that wrist-based optical sensors struggle with more.  Areas such as kettle ball usage for example.  Basically anything where your wrists are fully taut and at high intensity heart rates.

Now, in reading through the 42 page filing, it really centers on a couple of key items:

A) That the Fitbit Charge HR & Surge are inaccurate at high intensity exercise
B) That HR inaccuracy is potentially dangerous to an individual
C) That Fitbit’s HR inaccuracy wasn’t disclosed up front

There are some minor ancillary things they’re upset about, but the above is basically the gist of it.

So how is it dangerous to your health?  Well, here’s the applicable snippet from one customer:

“Plaintiff Urban is a fitness enthusiast who signed up for his first marathon in mid-2015. Given his father’s history with heart disease, Plaintiff Urban’s doctor recommended that he keep his heart rate from exceeding approximately 160 bpm…

…Even at high intensities it never displayed a reading over 125 bpm. Plaintiff Urban then cross referenced his Surge against his chest strap based triathlon monitor and found that the PurePulse Tracker consistently under recorded his heart rate at high intensities, often by as much as 15-25 bpm. In order to train effectively and safely, Plaintiff Urban needs to accurately record his heart rate during exercise so that he can reach, but not exceed, certain intensity levels. He cannot trust his Surge to deliver those accurate readings.”

All of which is a logical progression of thought, in theory.

But here’s the problem with this line of thinking: You can just as easily get an inaccurate chest strap reading too.  Why aren’t people suing Polar, Garmin, and Suunto and countless others making HR straps?  Up until the rise of optical HR sensors – one of the most frequently searched questions on my site was how to fix erratic chest strap readings (usually due to lack of sweat).  The symptoms were often very similar – either excessively high or low readings.

Which isn’t to say optical HR sensors shouldn’t be held to a higher standard – they absolutely should be.  It’s a core thing I’ve been doing here in holding companies accountable on poor performance.  But at the same time, it’s important that we don’t lose perspective on what that standard is or was with classic chest straps.

The lawsuit goes on to give examples where there are differences in readings between the Fitbit and other devices.  However, it makes some somewhat over the top statements that things often failed to record above 110bpm. What defines often?  More than 10% of the time? More than 50% of the time?


Either way, in talking with folks in the industry about this lawsuit this morning, there’s a lot of people scrambling to update websites today noting that their HR sensors (of all variants) are not designed to be suitable replacements for medical equipment (a statement you’ve undoubtedly seen numerous times before).

Valencell Sues Fitbit & Apple over optical HR sensor:


Not to be left out of the party, near simultaneously Fitbit and Apple were sued by existing optical sensor maker Valencell.  Readers here will be rather familiar with the company, as they supply optical HR sensors to one of my favorite optical sensor products – the Scosche Rhythm+.

The complaint alleges that both Fitbit and Apple met with Valencell in various locations and at various points to discuss using the sensor technology (licensing it).  However, it goes on to state that after neither licensed Valencell technology, both companies infringed upon patents by the company in a variety of areas.

You can read the entire lawsuit here against Apple, and here against Fitbit.  They’re actually really interesting reading, especially some of the quotes that various employees reportedly made while in the Valencell booth at CES in years past.

Now I don’t know enough about the very detailed particulars of the algorithms, chipsets utilized, or implementations of those in any of these products to make any determination of whether Valencell’s claims are accurate, since they require insider knowledge to know the answers to.

However, there are a few things I find interesting or notable:

A) If Apple and Fitbit did steal this technology – then…ummm…why are their optical HR sensors so much more inaccurate than Valencell’s (that they allegedly stole)?

B) Valencell noted in the complaint they are seeking a licensing royalty from each of these sets of devices.  This is interesting when combined with data from the unrelated class action lawsuit which specifies the number of optical HR sensing devices that Fitbit has sold about 3,015,000 in just Q1 of 2015.  If sales were even over the year, that’s around the 12 million unit range on optical HR sensing units.  And that’s before we even start talking Apple Watch numbers.

C) I’d be curious how/why companies like Garmin, Mio, Samsung, LifeQ, and numerous others wouldn’t be party to this sort of thing with their technologies.

The result of this lawsuit will definitely set the course for future legal action within the industry around optical HR sensing – an area that’s starting to explode with interest.

Investor Confidence Falls on Fitbit Blaze

Now what happened outside of the lawsuits is perhaps the most interesting news of the day: Investors and analysts actually got smart on the products.  I know this sounds silly, but the reality is that until this point, I hadn’t seen much independent thought in the segment (sports technology) from that crowd.  Instead, it’s usually filled with incorrect guesses that end up working out purely by brand associations.

However this time – everyone got it: The Fitbit Blaze was a product launch disappointment.  It missed the mark.

It was clear within minutes of leaving the press room (which probably had 150-200 people in it) that people were left a bit unclear on the direction of the product.  After exiting I had plopped myself down on the floor against a wall outside the room to write, and could overhear numerous phone calls being made all echoing the same sentiments.

It only took mere minutes for that news to make it to the markets, causing Fitbit’s stock to drop some 18.5%.  Today, they’re down 6%.


There’s so many facets to this that are interesting:

A) If you read various analysts comments about their concerns, they specifically call out a lack of Fitbit app market capability for 3rd parties.
B) Further, they specifically call out lack of GPS in the device, making it overpriced.
C) Next, they note concern about lack of overall features compared to existing offerings.

This is impressive.  This means that we’ve moved on from these devices being ‘all the same’ in the mainstream media’s eyes, to actually comparing very specific fitness features.  The same features that commenters say that ‘nobody cares about’.  Clearly, people do care about them.  A lot.

But, going back to the press conference – I wonder about one specific decision that was made by Fitbit: How much of an impact was it that nobody could even touch the screens on the devices and try them out?

Basically, following the press event, everyone walked up, snapped a photo at the front of the stage of two small rows of watches, and left.  End of story.


Had people had the opportunity to interact with the devices (as is common at Samsung, Apple, and numerous other press events), would that have changed things?

I bet it would have.  It would have attracted press to toy with features, and find interesting tidbits (like the Fitstar portions).  It also would have increased the people in the room’s time spent with those units, which undoubtedly would have bettered their opinion of it (even if only temporarily).  And, it would have delayed the onslaught of negative calls that I heard.  Likely changing those opinions from simply ‘Blah’ to ‘There’s one neat thing which is…”.  And that’s a huge difference in the fast pacing media world.

Today, at the main CES show, there are dozens and dozens of Fitbit Blaze units available to play with – and quite honestly, they’re much more impressive from a speed responsiveness standpoint and screen clarity than I got the impression at the press event.  Sometimes a little hands-on love pays a lot of dividends.


It’s ultimately a really interesting lesson in how the tiniest things in a product launch can snowball incredibly quickly into something really big.

With that – thanks for reading.

Don’t forget to check out all of the DCR CES 2016 coverage, as well as a slew of updates that were only seen on Twitter.  It was a crazy busy week!


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  1. Jeff

    Super article which provides a great deal of insight. It is interesting how quickly the watch was so universally panned. It made me sit up and take notice. Thanks for adding some informed comment to that piece of news.

    One minor edit – section B of Valencell -“event” should be even?

    • Tomas

      except for the lawsuit commentary. Really lawsuits are just allegations and they are notoriously fully of hyperbole. it’s no surprise to anyone who spend any amount of time reading them.

    • Nigel Pond

      Exactly, they’re designed, at least at the outset, to encourage the defendants to settle so that the plaintiffs lawyers can get their slice quickly and move on to the next case…

  2. Andy

    Thanks, Ray; great read!

  3. I have to agree with you about needing to pick something up and play with it before you can really form an opinion. I have bought (and returned) the Fitbit Charge HR, Fitbit Surge, Basis Peak, and Garmin Vivoactive…all because they just didn’t work as well in real life as their manufacturers like to think. I finally settled on Garmin Vivosmart, but had to compromise a few lower-priority features to get the ones I really wanted. I look forward to the day when this market segment has settled a bit!

    • Paul Allen

      I’ve just received a Vivosmart HR, and am enjoying it, buy thinking now that a GPS wouldn’t be a bad idea. Why did you move from the Vivoactive Kim?

  4. I’ve been wearing a Fitbit Charge HR for over a year, often at the same time as a Garmin, or Wahoo chest strap monitor. I don’t expect it to be extremely accurate, but it is. It provides more of a smoothed out heart rate graph, but that’s often a more accurate portrayal of one’s level of activity for the day, and that’s what it’s for.

    If you don’t like your Fitbit, take it back. Lawsuits are for when people actually cause damages to you.

    As for the copyright lawsuit, if I was sued in such a way, I’d be extremely relieved that Apple was named a co-defendant. They won’t even need to send their own lawyers. :-)

    • Nigel Pond

      It’s a patent infringement lawsuit, nothing to do with copyright. Patents are for inventions, copyrights for “original works”, designs etc and trademarks for, well, trademarks. OK I’ll fess up, IAAL (though not a litigator).

    • Paul Gardner

      I too have been wearing a Fitbit Charge HR for a year and thought it was fairly accurate with the exception of high intensity intervals. BUT after buying the Garmin Forerunner 235 and doing some comparisons I can see that the Fitbit appears way off when keeping generally busy and walking around. Have a look at this comparison when I was doing some jobs around the house and cooking dinner. Over a 1.5 hour period the Garmin reported (I was wearing a HR strap and periodically doing manual checks) an average HR of 66bpm. The Fitbit was 103. I.e. a huge difference. The Fitbit was spiking and gradually coming down to normal levels then repeating.
      I also found when doing morning activity on my indoor bike in a cold room the sensor took up to 15 mins to catch up to my true HR.

    • Paul Gardner

      I would like to add that I won’t be suing Fitbit. I will just wear the Garmin and use a strap when I feel its inaccurate and move on with my life!

  5. ian

    On the first charge if people were unhappy with the devices why the heck did they not take them back ??

    Ok this is the land of the lawsuits but if it was quickly realised at high intensity the HR was wrong, get your money back, but to sue ??

    Some people are just idiots but sometimes the judicial systems help them.

    • Tomas

      We have class actions for a reason. One idea is not to enrich anyone plaintiff but to “punish” a particular bad actor or company. If FITBIT was doing something wrong, we’d want them to be held accountable.

    • John

      “We have class actions for a reason.”

      Class action lawsuits enrich lawyers while the class members get meaningless tokens of nominal value for their trouble.

      If this particular suit is won or (more likely) settled, the partners in the law firm would each be likely to be able to buy their own Bahamian islands while the class members would most likely to get a voucher worth possibly $5 or $10 toward the purchase of some future Fitbit product.

    • Tomas

      unfortunately I can’t disagree, but just because that’s an outcome today no need to get rid of it.

  6. Steve

    I am a Garmin guy but I love the Fitbit TV commercials. They are by far the best in the industry.

    On the subject of the class action lawsuit, if Urban is that concerned that he might die if his heart rate exceeds 160 bpm then he should consider a more sure fire method of determining his heart rate like counting his pulse. I might die while exercising too but if I do I am not about to blame my heart rate sensor.

    I agree that the Fitbit Blaze is not everything a person would want or can buy in that price point which might justify the stock price drop, but the class action lawsuit is nonsense and should be promptly dismissed.

    • MattB

      “Plaintiff Urban’s doctor recommended that he keep his heart rate from exceeding approximately 160 bpm…
      …Even at high intensities it never displayed a reading over 125 bpm. Plaintiff Urban then cross referenced his Surge against his chest strap based triathlon monitor and found that the PurePulse Tracker consistently under recorded his heart rate at high intensities, often by as much as 15-25 bpm”

      By my reckoning 125+25=150, well below his doctor’s “approximate” limit (what even *is* an approximate limit?!), so good luck proving that was dangerous with such a woolly set of figures and definitions. If he already had a chest strap, then surely he’d have a reasonable idea of what 160 feels like anyway?

      I’m all for pushing companies to have accurate devices and honest marketing, but this just smacks of lawyers using a few disgruntled people to make themselves rich.

    • Steve, I agree. These devices are now reaching out to the “wider” community. Unlike us fitness nuts and athletes, this wider community doesn’t want to be responsible for it’s own actions. Any semi-intelligent person would do the research if your life depended on it. Mr Urban just wants a quick buck and I hope the lawsuit ends up where it belongs, in the bin.
      As for Fitbit reliability? Let the market beware and do it’s research. That is what led me to Ray’s excellent blog in the first place.

  7. Gabe

    Ray – i do think it’s dangerous that the optical HRs dont track well.

    When i was running intervals with the garmin 235 – it said I was still in zone 2 when i clearly was in zone 4!

    if i actually tried to exerted even more intensity to reach zone 4 i would have have passed out lol

    Garmin, fitbit, etc. should start posting warnings about the accuracy of the optical heart rate devices for having lag that could pose dangerous for some.

    BTW are you already sit of CES and eager to jump on a plane home?!

    Thanks for the write up once again

    • tri-athlete

      Maybe you should see a doctor, if you can’t understand if your body is on z2 or z4.

      The thing is, whatever the device, you should listen to your body and not rely on electronic devices blindfoldedly.

    • Paul Gardner

      Garmin already do post a warning. There is an link on their Garmin Connect site. I’m pretty sure Fitbit do something similar.

      Garmin activity trackers are intended to be tools to provide you with information to encourage an active and healthy lifestyle. Garmin activity trackers rely on sensors that track your movement. The data and information provided by these devices is intended to be a close estimation of your activity, but may not be completely accurate, including step, sleep, distance and calorie data. Garmin activity trackers are not medical devices, and the data provided by them is not intended to be utilized for medical purposes and is not intended to diagnose, treat, cure, or prevent any disease. Garmin recommends that you consult your doctor before engaging in any exercise routine.

  8. Rfb

    Good article.

    Is it just a coincidence that the lawsuits were announced a day after Fitbit announcing a new product. Conspiracy?

    A) If Apple and Fitbit did steal this technology – then…ummm…why are their optical HR sensors so much more inaccurate than Valencell’s (that they allegedly stole)?
    On A, are they actually using Valencell’s technology or did they try to copy it hence why it doesn’t work as well.

    C) I’d be curious how/why companies like Garmin, Mio, Samsung, LifeQ, and numerous others wouldn’t be party to this sort of thing with their technologies.
    Do those companies have a disclaimer that says the hrm tacker isn’t as accurate as an actual one? I don’t know a lot about fitness trackers and hrms. I’ve only owned a Garmin Vivosmart and a misfit for a little more than a year. From what I understand, I know Garmin have a disclaimer about the step count having an inaccuracy variance.

    • Chris

      You can’t sue someone for experimenting in their own lab; you can only sue when they introduce a product. Hence lawsuits right after product intro.

      Here’s what undoubtedly happened, based on what’s in the lawsuits:
      – Fitbit wants an optical HR sensor and starts talks with Valencell
      – Fitbit engineering works out rough product and starts to refine details
      – The accountants freak out at the Valencell pricing
      – Fitbit engineering is forced to design their own sensor, based on the knowledge they’ve gained from Valencell
      – They’re short on time, and don’t do all the R&D that Valencell did
      – Ergo: a valid lawsuit, and a reason the Fitbit HR doesn’t work all that well

      Other companies using optical sensing weren’t in extended engineering talks with Valencell, and so were able to develop their own units without infringing on Valencell’s rights. Apple and Fitbit are probably the only two companies that signed agreements to share engineering information; hence they’re the only two targets of the suits.

  9. Joe E

    Fitbit Charge HR does provide a lagging and inaccurate HR, that’s why I returned mine. Don’t see this case going very far, beyond harming Fitbit reputation.

    Fitbit Blaze is another product without a market. I see that they feel they need to compete with the Apple Watch, but this is not going to do it. Taking Apple head on in their backyard is a mistake.

    Fitbit would be better off on focusing on what they have built, an interactive user base that motivates people to move. It is still compelling and the device is not what drives this. They would be better off leveraging this portion of their model and allowing others to use their site and data model through licensing and keep their core the data and community and stop trying to make too many devices. Some good core, simple devices and a data / community centric business model is their best bet. If they let someone else take this space with Healthkit, or something else and it becomes the de-facto choice, they are done.

    • J

      Actually, price aside, the Blaze is a product for my entire family. Using my significant other as an example:
      – she couldn’t care less about the GPS – she runs, but does not really care about any analysis (she has a garmin, does not use it)
      – she does run with music occassionally but is not too interested in apps overall
      – she wears her fitbit all day but uses a One as she does not find the band formfactor too appealing
      – she would benefit from the extra features (sleep tracking, RHR etc)
      – she would like the customization
      Same (or similar) would apply to my dad who also uses fitbit.

      The biggest issue might be the price, but I wouldn’t be as harsh as saying the device does not have a market. Fitbit has a history of releasing devices appealing to mass market and simple yet accurate enough.

      I agree though that fitbit will need to think hard about whether going forward they will produce “tracker” apps for competing smartwatches or not… losing device revenue but keeping relevance.

  10. setj

    I still wear my trusty Fitbit Flex. It does everything I need it to do, namely, it has a silent alarm. As an athlete, the number of steps I take is irrelvant to me, especially if I biked or swam earlier that day (not counted). However, at first glance, the Blaze did look interesting, until most media panned it. I do believe it should have standalone GPS, but if they can make it a true companion device, like the Apple Watch, and possibly lower the price a bit, it could be an interesting product.

  11. Mike

    A) I was following the Fitbit event on Twitter and my initial reaction was one of disappointment in the Blaze. First, I thought it was rather ugly (I’ve since softened on that stance though I don’t think its great looking), and 2) I was shocked it doesn’t have GPS. Ultimately, why would you want a Blaze over either a Charger HR or Surge? Seemed like a step backwards. I hope I’m wrong.

    B) The Valencell lawsuit against Apple alleges that they wrongfully downloaded white papers. That is a strange assertion – aren’t white papers 1) Shared publicly, 2) an illustration of the drafter’s research and/or hypothesis, and 3) meant to be educational?

    Question: Is the Rhythm+’s accuracy increased by its placement on the forearm and/or by the type of strap worn? Or, is it because the sensor pod is so large and all light is blocked out? I wonder if the Apple Watch would be more accurate if there was a large strap like that allowed it to be worn on the upper arm like the Rhythm+.

  12. P

    Perhaps it would be better to not reference stock reactions on a site like this.

    If you look at Key Stats on yahoo finance you will see that 78% of the float is short on Fitbit, this number is probably not accurate anymore. However, people that short stocks are typically more sophisticated then the general public. However larger short interest’s cause stock to react in big ways.

    Prior to this correction, Fitbit had a market cap of about $6B versus Garmin at $7B yet Garmin has 5 different revenue streams versus one for Fitbit. Garmin Profit will be substantially higher than Fitbit’s now… the future is not clear. That said, the Fitbit software platform (and management team/software engineers), is more cutting edge than what Garmin has.

    So without a good story on how Fitbit was going to increase their addressable market, those short the stock had a good reason to look past Fitbit being the most downloaded app on Itunes…. and push the stock to a level that more realistically represented future earnings.

    Of course this doesn’t compensate for the Osborne effect – meaning that Fitbit didn’t disclose all of their future products for the next year.

    • I’m pretty sure even Fitbit wouldn’t say they have a more advanced platform that all of Garmin’s platforms. But they don’t need to.

      As for not mentioning the drop, that’s silly. It’s important, as it’s a clear indicator investors weren’t happy. Adding another group that didn’t find the announcement worth while.

    • Matthew B.

      Sort of expanding on P’s comments, it was interesting to see many investing site articles about 3-4 weeks ago saying how great Fitbit was doing, then about 1-2 weeks ago the advice was “doom and gloom is coming for Fitbit” stating that they had nothing to offer since their device was becoming a commodity (I would argue their platform is extremely powerful and is almost as or more important than the device). However, most of these articles noted that while they didn’t own stock in Fitbit at the time, they *may* short the stock in the next 24-72 hours.

      It all seems very, VERY fishy to me. Like this reaction is partially to manipulate the stock price to make some people a lot of money (and perhaps people had some inside knowledge that the lawsuits were impending).

      I’m honestly surprised at the negative response to the new Fitbit watch. It’s obviously not their high end “fitness” watch (they group it with the Charge HR, not the Surge) so not having GPS makes sense, yet the masses seem extremely upset about it. The lack of true waterproofing, IMHO is a miss, but not a complete deal breaker. Overall, it seems like a great platform to build the rest of their line around for the next 1-2 years.

  13. Lee D

    The accuracy of the Charge HR is a well-discussed complaint on the Fitbit forums but the lawsuit is missing the point. As Ray demonstrated and can be easily seen for yourself, at a consistent pace it works to an acceptable level. I wear mine as an activity tracker for general purpose use and when running or cycling I use other devices simultaneously for more accurate readings. It also means I can see when the Charge HR is at a concurrent reading too and when I have to let it catch up.

    The problem for Fitbit is that their marketing and PR keep promoting it for exercises where it will not be able to keep up or just doesn’t work to any acceptable degree – like cycling or strength training – because by the time the sensor can catch up to register a reading the recovery rate has already made the reading useless.

  14. Long Run Nick

    Ray, thanks for the interesting report. 40 years ago, I was thrilled to find a little Casio watch that had a stop watch. Wow!!
    I continue to be fascinated that even with all this tech stuff (which I love), the obesity rate in the US continues to rise. Must be the faulty HR optical sensors.:)
    The other interesting aspect is how few folks actually know what their max HR actually is, relying on the old 220- your age, which sadly only works for about 30% of the population. Thanks for letting me share, oh damn, the nurse is taking away my I-Pad.

  15. David

    I believe the Blaze is Fitbits solution to the Vivosmart HR, Microsoft Band 2, Polar A360 and other bands with large screens. Many users want the advantages that come with large screens (notifications, live data etc.) but the “big screen band” is polarizing. Watches aren’t polarizing, they classically come with large screens and in this form factor Blaze has the chance to show users lots of data while maintaining a classic look.

    What I do feel is significant is what Blaze means for Fitbits line of bands, Flex and Charge. I assume Fitbit (in particular now after the stock hit) will have updates to the 3 and 2 year old designs this coming fall but I feel they will retain the small/minimal screen look that allows they bands to be worn by soccer moms, teens, business men and women alike. Perhaps smaller with better sensors but I doubt now more than ever that Fitbit intends a Vivosmart HR, Vivofit 2, Microsoft Band or Polar A360 style band because they have the Blaze for that.

    It’s too bad their presentation (smartwatch, really?) got so lost.

  16. trickycoolj

    I was quite puzzled by the Blaze yesterday as well. Without GPS it doesn’t compete in the Garmin arena and without any kind of apps it doesn’t really compete in the smart watch arena either. The Pebble Time can be found cheaper and also just added native sleep/step tracking just before Christmas. I’m a devout watch wearer even prior to smart watches and haven’t really been compelled to switch to any wrist based trackers or watch style trackers because most don’t go from Gym to office very well. So I still have my tattered Fitbit One hidden in my pocket though admittedly it doesn’t get used much these days because I prefer all the 3rd party interoperability and HealthKit integration of my Pebble and Garmin devices. I think Fitbits only market these days are the Costco masses that see a 2 pack at the door and don’t know anything about features.

    • David

      I’m glad you like the Apple HealthKit integration but HealthKit is a mess. A real mess. The fact it isn’t in the cloud, that the app is a UI disaster and more just adds to the problem. Fitbit is simple and it works. There is a reason I own a $600 apple watch and have a fitbit band on the other arm. I suspect Apple will get this fixed in time but it hasn’t happened yet.

  17. Mikey

    In looking at the hr accuracy lawsuit, I don’t the case is really about the accuracy of the HR as opposed to the claims by Fitbit vs the actual performance. It’s a fraud and misreprentation claim.

  18. morey

    Sounds like a great time to buy stock in FitBit. The Blaze is a great looking (subjective, but I like it) $200 smart watch and activity tracker. It doesn’t have to be a GPS watch. The Apple watch isn’t, nor are most of the myriad smart watches out there that cost more and are less activity tracker/fitness oriented. And if you say it has a slick interface- I believe you (you’ve used enough of these products).

    Looks like a nice product to me, and a bunch of tech reporters just wanted to have a ‘story’ to punch. It’s always interesting reading to say the big man has fallen. er… not waterproof tho? ooops.

    • Mike

      The first Apple Watch doesn’t have GPS but Apple is taking health and fitness very seriously. Apple is going to do what it does best – iterate at much a much faster and more efficient rate than its computers until Apple Watch is superior or, at the very least, equal. That poses a big problem for companies like Fitbit considering Apple’s brand recognition and marketing prowess.

      Think about it – Fitbit is just now releasing the Blaze? Apple is going to release only its second ever wearable later this Spring, and its likely to be a big improvement over the first (Think about the iPhone’s rapid advancement). Fitbit should needs to be much further ahead to hold of Apple, not to mention Garmin, Polar, and the other companies in this space.

    • Neil

      @Mike – I’m not sure I agree that “Apple is taking health and fitness very seriously” as I really don’t see the evidence. Sure, Health, Healthkit and the built-in features of the Apple Watch show an interest in the area and announced Apple’s presence in the market, but I see this more as marketing features than any real commitment – how long since Health.app launched, and where’s it gone in that time? Sure, Apple likes to focus heavily on the health/fitness thing in its advertising, but that’s a “buy into the lifestyle” thing like car manufacturers marketing “sports” utility vehicles. Where Apple really want to make a difference, they can turn a segment on its head and I don’t see any sign of them doing this here. Rather I think this is just them making sure they’re not missing out on where the party is.

  19. Fitbit doesn’t have a market.

    It attempts to be a hardware company, but charges orders of magnitude more than its competitors. The only company that consistently succeeds in doing so is Apple; Apple has decades of name brand recognition and design experience.

    It attempts to be a social networking company. Facebook is a social networking company; Strava is a social networking company for athletes.

    Of course, I’m soured because I’m an unhappy Flex owner (both original and replacement failed within the warrany year).

  20. Dana

    FWIW, when I wound up in the hands of the EMTs after a recent 10K, I was wearing my Garmin chest strap and watch, and they noticed that the reading was within one beat of their own cardiac monitor.

  21. GregTR

    Ouch! That is one tough day indeed.

    Re: Fitbit Blaze
    I don’t think there is a market for this device especially at this price point. If I wear something watch like it better have GPS in it too!

    Re: IP Suit
    This one could hurt them in a big way if the allegations are true. The fact that they went after Apple too is not a good omen either, now they just need to prove it all in court.

    Re: Class Action Suit
    This one is pure bogus as are many class action suits. Unfortunately most often the damage is done even if the suit is bogus. I do have a Charge HR and I use it for daily HR tracking but I would not trust it for workout tracking and never have. As someone else already stated I also use a HR strap for that. Granted that my expectations were low to begin with I wasn’t disappointed with the product. Others obviously can have different expectations and if they are based on false advertising and false claims then there can be something behind the suit.

    Another thing to consider is that Garmin’s Elevate stack seems to fare even worse so far both in terms of accuracy/precision as well as in battery life. It’ll be interesting how they will handle the situation and the possible onslaught of disappointed customers.

  22. ekutter

    None of these devices have heart rate sensors that should be relied upon if you have potential heart issues. Around 2009, I kept seeing spikes of 225 on my polar HR monitor. Turned out I actually had an arrhythmia where my HR really would shoot up to that in certain running conditions. I still occasionally get those spikes but I never see it show up on my HR data as I suspect it either gets smoothed out or removed as a likely erroneous value. The HR monitor helped me detect this but I certainly wouldn’t have blamed it if it hadn’t.

    It probably would be good for warnings to be placed on these devices that they aren’t medical devices as there clearly are a lot idiots out there that seem to think otherwise. But this sounds like a lawsuit without merit.

    • Chris L

      I am fairly sure I have seen warnings on all the devices I have purchased that either have a built in HR sensor or pair with a sensor. That lawsuit will be chucked out pretty fast.

    • Nigel Pond

      You would think so, but that take time and costs money (costs which under the US system are not recoverable) , meaning that it’s often cheaper to settle and that’s what plaintiffs’ lawyers count on.

  23. Joe

    I’ve studied a variety of optical HR devices as well as chest straps on a large number of subjects.

    It is very clear that optical HR devices are significantly worse than chest straps for most people, most of the time.

    • Tim Grose

      Well I have my checked my calendar and it does not appear to be 1st April. Certainly feels like it.

      As such, a few things struck me as highly odd.
      “At the recommendation of his friends, Plaintiff Urban purchased a Surge…”
      Maybe Urban needs to sue his friends for poor advice?

      “Plaintiff Urban’s doctor recommended that he keep his heart rate from exceeding approximately 160 bpm”
      No explanation on why 160 is chosen?

      “Plaintiff Black’s personal trainer
      manually recorded her heart rate, which was 160 beats per minute (“bpm”)…. Plaintiff Black was approaching the maximum recommended heart rate for her age”
      Err? What based on 220-Age perhaps? Or is 160 some magic number we had all better stay under?

    • Nigel Pond

      Not in my experience. My MIO Fuse tracks pretty closely with my Garmin and Wahoo chest straps.

    • Tomas

      So you are a doctor now. What does it matter if it was 160, 150 or 180?

    • Tim Grose

      It was somewhat tongue in cheek but would have thought if you going to present some “good” evidence in such cases you would give a bit more reasoning to what you are trying to achieve and why.

  24. Michael Fiola

    Excellent article Ray, thank you.

  25. M3V8

    “A) If Apple and Fitbit did steal this technology – then…ummm…why are their optical HR sensors so much more inaccurate than Valencell’s (that they allegedly stole)?”

    As a patent attorney, I can tell you that “stealing” is just hyperbole…the critical issue is whether Valencell’s patent (i.e., the claims of the patent) covers the products made or sold by Apple and Fitbit. I suppose that Apple and Fitbit could have “stolen” based on whatever technical disclosure that Valencell provided them, i.e., develop their products based on these technical disclosures. But you don’t have to prove theft or stealing to have patent infringement. Even if Apple and Fitbit independently developed their HR technologies, if Valencell’s patent covers their products, then you’ll find patent infringement. Theft is not a requirement for a finding of patent infringement. Strictly speaking, theft is irrelevant but could be useful to sway jury members who are probably bored out of their wits in dealing with the esoteric intricacies of a patent trial.

    • Bert

      As an added note, with regard to why “Garmin, Mio, Samsung, LifeQ, and numerous others wouldn’t be party to this sort of thing [patent infringement lawsuit] with their technologies,” it could very well be that their optical HRM technologies are not covered by the claims of Valencell’s patents. I haven’t read through the claims, but I’d presume that the alleged infringed claims are probably narrow in scope and related to whatever technical discussions Apple & FitBit had with Valencell. Otherwise, it would be odd that Valencell would only be targeting those two companies. In full disclosure, I’m not an IP litigator so there could be other strategical decisions involved with not adding additional parties to the suit at this time. Also, could be that those other companies have a license agreement with Valencell, but that would cause one to question why their optical HRM technology isn’t up to par.

  26. Jared

    I like using HRM’s and they generally work well, but sometimes it’s just an “off day” for whatever reason and I get weird readings. I’ve learned it’s just easiest to just remove the strap or band I’m using and just rely on perceived exertion for those times. IMO, the doctor would have been better off to tell the patient not to exceed some perceived exertion level, e.g. not being able to carry on a conversation without gasping for air.

  27. Ray as you know I have a LOT of workout data across a lot of devices and I found that for “intense exercise” (particularly non-running – more like Crossfit or strength training or kettlebell training), the ChargeHR and SurgeHR were 20% lower than a Viiiiva chest strap and sometimes up to 30%. CONSISTENTLY. So I’m not surprised and I’m glad that this lawsuit is being waged because if manufacturers are going to say this is heart rate and others (health groups, fitness trainers, etc.) are going to deliver heart rate zone based prescriptive training, then that 10%-40% gap is massive and a significant health risk. This is a good development in the industry in my opinion. And of course Apple’s watch has the same issues and is equal or worse in terms of accuracy (for those use cases I mentioned).

  28. Paul D

    Careful Ray – or you’ll get dragged into a 12 month court battle as an expert witness. ;)

    Although that could earn you some mucho dinero!

  29. Chest Strap

    Hum…shouldn’t people also sue about spike heart rate reading in polar or garmin heart rate monitor?

    • Nigel Pond

      Could they, yes. You can file a lawsuit making all kinds of spurious claims if you pay the filing fee. Would it have much chance of success? Depends.

  30. Nice article. This story will roll and roll – as they say.

    IMO inaccuracy for nearly all of us is not dangerous. but for sure certain people will be told not to exceed certain HR level (they are usually on medications like beta blockers) and I’m not sure why they will be told to exercise at (inaccurate) high intensities.

    • TR

      The “dangerous” claim is just for exaggeration and extra media spin.

      Honestly how could a doctor even let someone to go on a marathon, if his physical condition doesn’t allow him to go over 160 bpm ? I’m not saying he should exercise, but it’s a friggin’ marathon not a 5k jog we’re talking about here.

  31. TR

    Thankfully to this site with its thorough optical HR testing, one can easily see if they’re ready or not.

    Personally so far, I’m still not convinced (while some products are very close). Either the recorded heart rate is always accurate, like usually on the HR belt, or it doesn’t even matter if I record it or not.

  32. Hammer

    Surely all FitBit need to do is show up on the first day of the trial, say “the Fitbit is not a regulated medical device and makes no claims to have the accuracy of same”, mic drop and walk out?

    You can’t expect a $1500 ECG-level suite of medical sensors in a wrist-sized device that costs less than $300 and lasts for multiple days.

    The share price thing is very indicative of the investment bubbles around fitness companies. It’ll probably start to deflate towards the end of the year, given the difficult of innovation in the field (see Fitbit and Jawbone) and efforts by established companies like Withings and Fossil to integrate sensors into traditional watches.

    • So it’s funny, I stumbled into a DCR reader (or rather, they stumbled into me) walking the floor today who happens to both be in the investment space as well as covering the medical device realm with a bit of the fitness stuff tossed in (also is also a Dr.). So basically, he knew all about these topics.

      I asked him essentially they question, and he said that ultimately that merely claiming lack of medical device wasn’t good enough. He said that if Fitbit ever hinted at it being a viable option for medical usage, then that’d immediately open it up. The example he gave is that often times companies in the field that are not medical devices will put it all on the packaging that it’s not a medical device, while then turning right around and telling doctors quietly on the side that it’s just fine to use. But he said there were numerous variations of that type of indirectly calling it suitable.

      He didn’t have any comment on the Fitbit case specifically, just talking generally.

    • Will Luttrell

      That’s fine from a medical device standpoint, suing based on medical reasons.

      But then there’s an entirely different standard more commonly held: Fitbit sold a device based on marketing that it could do certain things (i.e. pictures of people lifting weights and monitoring their heart rate) which the device cannot do.

  33. david n

    As a side note to spiking HR readings: I always had spikes in winter time for the first ~15 minutes of the workout until it stabilized. I first thought I didn’t wet it enough – but that was apparently not the case. As it turns out, it was the polyester fibres of my clothing. When I rode the bike and the shirt started to flap, the HR started to spike. Lesson: I only use natural fibres in winter (Cocona, Merino and the like). Would be interesting to know, if static eletricity also has an effect on optical HR sensors. I’d assume less than the standard chest straps.

  34. Worthless lawsuit and I hope they loose. BPM is beats per minute and what most of these fitness devices do is take the time between two heart beats and try and extrapolate that to a BPM reading. Anybody that exercises and monitors their heart knows that your heart beat changes constantly as per demand from your brain. Flap your arms and watch your HR climb and then stop flapping your arms and watch your HR slowly return to normal. When I had the dreaded butt check that we all should do when we turn 50, I was hooked up to the EKG machine and I was playing with flapping my arms and kicking my legs and watching how my heart went up and then recovered until the nurse told me that I needed to play nice. And these HRMs are not medical devices, the same as the home BP cuff testers are not medical devices.

  35. Tom Albrecht

    Typo: “Now, my guess is that the plaintiff’s” plaintiffs is not possessive.

  36. Henry Hoverball

    Wow, given the state of Garmin’s new OHRM, they must be defrosting landsharks and re-weaselling publicity material even as we speak :)

  37. Will Luttrell

    My experience with the ChargeHR was that it *never* catches up during various exercises like weightlifting, rowing, crossfit, basketball. If you use it only for running, it was marginal but acceptable.

    I predicted this lawsuit when the Device first came out, loudly, on their forum.

    Ray had an above-average experience with his devices, in my opinion. They flat out don’t work for many many people.

  38. bartus

    If I were Valencell I would drop that charge and forget about it real quick. My reasoning for this is that if Fitbit and Apple were to be forced to pay patent fees to Valencell, Valencell as a company would be responsible for the workings thereof. This means that if Fitbit loses the trail regarding the sensors that have Valencell patents at their bases, Valencell has accountability. The same things happen within the pharmaceutical industry. If a company decides to make generic drugs based upon a patented formulation and complications occur, the company that owns the patent is held responsible because they did the original research.

    • Matthew B.

      Insert Meme: “That’s not how this works, that’s not how any of this works.”

      Fitbit’s suit is related to their marketing of the claim of accurate HR. Additionally, knocking off someone’s technology is not the same as using their technology. Generics and drug formulation is an extremely specific instance of this and doesn’t translate to the sports technology field.

  39. Bryce

    I kind of wonder if you might be called on to be an expert witness. I don’t know of anybody else that could speak to the accuracy (or lack thereof) of optical hear rate monitors.

  40. Ken

    Good!! Now maybe we can all stop pretending optical sensors in activity trackers are an option for high intensity workouts and get around to offering the ability to pair with a chest strap. Listening Garmin? Probably the only thing preventing a large portion of people considering activity trackers from buying a Vivosmart HR.

    • Except that some optical HR sensors are indeed perfectly capable of tracking high intensity workouts, as shown by myself and many others here.

      Unfortunately, the landscape is littered with bad options, from reputable companies as well.

    • gabe

      are you speaking of the scosche? Do you believe optical is more accurate with placement on the arm versus the wrist?

    • Largely, yes. If I look at feedback on the Scosche and accuracy, it’s overwhelmingly positive. Very rare to find an outlier there.

      I do think a large part of that is due to the placement further away from wrist, which reduces issues with light below the sensor because of specific user placement (i.e. Wrist bone, slippage, etc…).

    • GregTR

      I have used the Scosche on my upper arm for hockey and it worked really well while my FitBit generally has me at 115 bpm for the whole hour in reality I often hit mid 180s during shifts.

      Hockey is an excellent test for optical sensors. It is very high intensity repetitive short cycles for long periods of time with high amount of upper body, arm and hand movements. If an optical sensor can handle it then it should be able to handle anything.

      So I whole heartedly agree that FitBit is total garbage for hockey the Scosche on the upper arm works great. My son has a Garmin 235 but I make him wear the chest strap for his hockey sessions as the optical sensor in the Garmin 235 would not stand up to the challenge of hockey. And even though the Scosche works I still prefer to wear a chest strap and only use the Scosche if I forget to pack my chest strap.

      I’m one of those weirdos who doesn’t mind the chest strap at all but looking forward the optical built-in wrist sensor for all-day use, currently a feature that FitBit does fairly well and Garmin is failing at.

    • Joe

      IME, yes the forearm yields much better signal than the wrist on most people.

    • Ken

      I feel like I have read a thousand reviews and comments for various trackers with optical sensors and the common denominator in a large majority of them have some form of the statement, “yeah, great for counting steps, sleep, in some cases running, and resting heat rate, but not for anything else” ie weight lifting, crossfit etc. My personal experience is with fitbit charge HR and Surge both giving poor results in cycling and weight training. I understand they seem to work for some people but given feedback I have read, they are in the minority. To bring this comment back on point, I personally don’t think these companies should be making promises or suggest they will perform well in environments where they clearly don’t. I noticed the new Fitbit packaging actually has a barbell depicted. If I didn’t know better I would think “that’s great! It will work well in the gym”! Sorry, already got me twice! I won’t waste anymore money on optical trackers unless there is an option for a chest strap for gym work and other activities where they clearly fall short of promises.

  41. Eric

    The plaintiff’s has a legitimate concern as we all should as well.

    There are several important things to learn from this that these fitness tech companies need to consider when designing their products.

    First off, the inaccurate optical HR sensors is a no brainer – how can estimation of HR from blood flow at the wrist accurately reflect electrical activity of the heart?, especially at high exercise work-rates. Confounding variables such as age, body fat and even skin blood flow during exercise can decrease the accuracies of these devices that I don’t think these companies think about.

    Secondly, exercising causes an increase in skin blood flow, especially during exercising in hot conditions that will decrease the accuracy. We did a study with a NIRS device that measured tissue oxygenation during passive heat stress and resting under a thermal neutral condition and found the increase in skin blood flow under heat stress reduced the accuracy of tissue oxygenation compared to (See here: link to ajpregu.physiology.org). I think the same is a problem for these optical sensors.

    Lastly, aging and obesity causes a reduction in vascular function. So if you are using data (logarithms?) from healthy young individuals, these will not be the same for aged and (or overweight) diseased populations.

    • So many things inaccurate here. Actually, everything you said is incorrect.

      “First off, the inaccurate optical HR sensors is a no brainer – how can estimation of HR from blood flow at the wrist accurately reflect electrical activity of the heart?, especially at high exercise work-rates. Confounding variables such as age, body fat and even skin blood flow during exercise can decrease the accuracies of these devices that I don’t think these companies think about.”

      No, not all units are inaccurate. Just like not all cars are awesome, and not all cars suck. As for the ‘how’, it’s been well proven already by certain companies. The fact that Fitbit’s may or may not be accurate doesn’t represent everyone.

      “Secondly, exercising causes an increase in skin blood flow, especially during exercising in hot conditions that will decrease the accuracy.”

      Also incorrect. In fact, it’s the exact opposite. Colder conditions is worse, hotter conditions is downright awesome for optical.

      “Lastly, aging and obesity causes a reduction in vascular function. So if you are using data (logarithms?) from healthy young individuals, these will not be the same for aged and (or overweight) diseased populations.”

      There’s zero evidence (informal, formal, or even carrier pigeon) for this statement. In fact, again, the opposite is correct. Overweight people generally have an easier time with optical HR sensors because there’s more ‘meat’ for an optical sensor, compared to a super-thin runner with boney wrists.

    • Eric

      They are incorrect because you have tested it? Just because it works well for you (an n=1) doesn’t mean it is generalizable the whole population. Again, especially or aged or obesity was the main point I was making.

      It is well established in the literature that vascular function is impaired in the aged and disease population. Not sure I understand your point.

      We showed the NIRS device does not account for the increase in skin blood flow during heat stress. I was making an assumption this may be the case for the optical sensors.

    • Joe

      Blood perfusion and optical sensor SNR is significantly increased in warm vs cold weather across many people I’ve tested.

    • Eric

      I would assume so. I would also assume the SNR are attributed to the increase in skin blood flow. The cardiovascular system serves two roles: maintaining blood pressure and temperature regulation. My concern with the accuracy of these sensors are that if the hemodynamics of estimating HR from blood flow at the wrist are under neutral conditions, but then under heat stress you have an increase in skin blood flow of up to 7-8 l/min (serving a different role – dissipating heat), how does this affect the accuracy of the sensor?

    • Eric

      Also, your comparison to cold weather is not a fair comparison because cold weather presents the opposite response/concern – vasoconstriction, compared to hot and neutral environments.

    • “They are incorrect because you have tested it? Just because it works well for you (an n=1) doesn’t mean it is generalizable the whole population. Again, especially or aged or obesity was the main point I was making.”

      Me and thousands of others that have actually used the devices and posted here. This isn’t new stuff, nor is it mysterious or complex. Again, like any product in any market – some do it poorly, and some do it well.

      “It is well established in the literature that vascular function is impaired in the aged and disease population. Not sure I understand your point.”

      Your original quote was that it decreased accuracy. My point is it doesn’t. It actually increases accuracy of optical HR sensor.

      “We showed the NIRS device does not account for the increase in skin blood flow during heat stress. I was making an assumption this may be the case for the optical sensors.”

      Different technologies.

    • Joe

      The LED emits a light into the various tissues in the skin, some of which is absorbed and some which is reflected back to the photodiode sensor. The majority of what is reflected back comes from “static” tissue that doesn’t contain any information about heart rate. When the green light hits the blood, it can be absorbed. When there is more blood (pulse), LESS light will be reflected back to the sensor. But when there is less blood (diastole), more light will be reflected back. So ideally you want to see a large CHANGE in light absorption / reflection, as this change will lead you to estimate heart rate.

      So, if there is more blood flow from heat, if it still provides pulsatile variations, then that should improve SNR. But I should go test in the sauna / steam room to verify :)

    • Eric

      Do you and the thousands of people that have tested it have obesity, diabetes, cardiovascular disease?… :) – I get your point, you have seen a trend. But again, going back to the law suit you posted up, aged and CV disease my not reflect the responses shown in healthy fit people. These are important factors that should be looked at, especially, if they are marketing these devices to unfit, unhealthy people to assist with exercise intensity (HR).

    • Eric

      Joe- Thanks for the quick breakdown on how it works. That would be an important question to answer, if the pulsatile variations in the skin blood flow reflect arterial blood flow.

  42. TomG

    Great article!
    I have a Charge HR. When I am running on the treadmill, I find it won’t measure a heart rate over the 150s. Even though I know it is probably close to 180. It seems to my Charge HR is ok for a slower 80% Max HR workout. But, if I want to push my workout, it is always useless since it never measures higher than the 150s. My Garmin strap also has accuracy issues at times, but I can tell when it is on. When it is wrong, it is often very wrong.
    Like measuring 200bpm when I just started my first easy run or its at 120 bpm when I am about to pass out and die. The fitbit error looks like it might be right, but it really isn’t.

    That is my experience anyway.

  43. Eric

    Fitbit Blaze, because the only thing its good for is setting on fire.

    Seriously though it’s big, its ugly, and most importantly it has no GPS. Not sure what they were thinking….

  44. Harrison

    Optical heart rates were originally designed for stationary measuring. My doctor smirks when he started to see these products coming out for fitness a couple of years ago.

  45. ted b.

    Great article Ray, definitely appreciate the unique insight!

  46. Kevin F

    Interestingly .. I was a former Fitbit Surge owner (for all of 3 days). The breaking point .. spin class which I do often. But my Nike and chest strap was saying 170+ .. my Surge was at 86. That to me .. a deal breaker. I ditched it and never looked back. Even though .. I really did like Fitbit. It was overall pretty good .. with no bugs. I cannot say the same about my Garmin fitness device. .. it is dreadful. I am really on the fence .. and will stick with my Garmin for now. But I could be back .. there is a big reason why Fitbit is number one, and Garmin number 4.

  47. Phyllis ullman

    I just got mine a week go or more or less. I checked out and I noticed steps and heart beat were not accurate. I now keep using my cell phone app! It’s is accurate!

  48. Phyllis ullman

    I would like my money back!! $149.00!!!!!!

  49. Starlinguk

    I have a fitbit Alta without HR. It hurts like hell to wear. I also tried a flex 2. Same problem. Even just holding it in my hand hurts. Fitbit knows about this problem and refuses to fix it. I’m waiting for a lawsuit.