Training For A Marathon: 8 Wearables That You Should Avoid

Training for a Marathon: 8 wearables that you should avoid

Preparing yourself for a marathon it’s a long process that takes a lot of time, dedication and training. One thing that you MUST incorporate into your running routine is the usage of a wearable device that helps you monitor and tracks your pace, time and distance. That way you won’t get any surprises when race day will arrive.

Smartwatches and activity trackers are the most common devices used to give you accurate fitness data that helps you improve your runs during your training. But not all wearables are precise when it comes to long runs like half-marathon or marathon distances. Which? has recently tested 8 wearables devices that you should avoid if you are training for a marathon due to inaccurate distance tracking. They compared more than 100 devices and here’s a list of the worst ones.

Big guns like Apple, Fitbit and Garmin (just to name a few) are all on that list, so make sure you eliminate these specific models below from your buying list.

Note: Which? tests have been done from May 2016 to February 2018. The list doesn’t include the latest models from 2019.

Less Accurate Model: Garmin VivoSmart 4 (

Inaccuracy : -41.5% )

The Garmin VivoSmart 4 is the wearable that gave the worst accuracy during a full marathon. This fitness tracker underestimate the distance by almost 11 miles! Slow down and take a nap buddy, you deserve it! 😉 Not having a built-in GPS (only accelerometer) doesn’t help this activity tracker at all.

In Which? test, the actual distance ran by the athlete was 37 mile instead of 26.2. Crazy!! Not throwing out the ball at Garmin though. The previous version of the VivoSmart was rated way higher (tested by Which?) than his new version.

The Samsung Gear 2 is also a bad choice with an inaccuracy of – 38% followed by Misfit Ray (-32%) and the Xiaomi Amazfit Bip (-30%). To go back to Garmin, if you want a decent watch to calculate your distance more accurate, go for the Garmin VivoActive 3.

Apple Watch 2 Series Is Overestimating by 13%

Apple Watch 2 Series (Credit: PCMag)

Apple’s 3rd generation of Apple Watch (GPS version) has also disappointed when tracking a full marathon by overestimating the distance by 13%. So, instead of running a real 26.2 miles you will run less due to the lack of imprecision.

But iOS users don’t get worry, Apple Watch Series 1 finished with great results overestimate the marathon distance by 1% only. We don’t know the results of the Apple Watch Series 4 but I am pretty sure it did well. Still, who runs a marathon with a iOS device? Most athletes uses other brands when running long distances. Thinking about the Garmin Forerunner/Fenix or the Polar Mxx series just to name a few.

Huawei Watch 2 Sport is overestimate the distance even more. 28% to be exact. So make sure you put this one on your blacklist too! Huawei got words of the bad readings and are telling that test conditions and runner variances can modify the results and they are also committed to a better running experience for his clientele and will keep optimizing their existent and next generation of watches. One step into the good direction…

Ask a Running Specialist To Make The Right Decision

There’s always a running store in your local area and I suggest you ask for their insight to make a clear decision when you want an accurate fitness watch for long runs. More specifically for half-marathon or full marathon. Using a precise wearable during your training will help you ”tune” your pace and give you the right distance to emulate what will happen during race day.

What do you think of Which? test results?

Do you have one of these watches from the list?

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About Alvaro ''Al'' Paez

I am a passionate fitness/wearable enthusiastic person who loves to share to the world, news and reviews about what I call fitness wearables. Ive been using wearables since many years and I found they can be a useful tool to improve your health, increase your fitness level and lose weight. There's a fitness wearable for every person. Let me show you the good path! Alvaro ''Al'' Paez.

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22 Comments on “Training For A Marathon: 8 Wearables That You Should Avoid”

  1.  Thank you for sharing this article. I run a little so it was very interesting to note which devices did the best and which did the worst. I have always been interested in training for a marathon so I may use this information to decide what kind of device I need.  However I am a big Apple fan so I may be looking into the series 4 Apple Watch.  I would love to know results from that test. 

     Thanks again and I appreciate you sharing this article!

    1. Thank you for the comment Jackie!

      If you are planning a marathon, the Apple 4 is a great option…better than the Apple Watch 2 Series 🙂 

  2. This is good to know, thank you! I never have used any one of these, but they seem interesting. How helpful are the good ones? What do they do exactly? I’m in the dark ages when it comes to these, because I don’t work out much. Monitor heart beats, steps, or both?

    1. Hi Buffy, 

      You should read the reviews to compare them. This tells us that you have to pay attention that even high-end watches can be inaccurate and you have to get the more info possible to make the right choice. 

  3. Hi 

    Great post I would have trusted these watches, i currently use the Samsung  S8 and i use the fit bit on there now that has made me think twice after reading this really good read and knowing how inaccurate they are is annoying as a lot of people rely on them.

    1. Hi Tracey, 

      You got that right. What Fitbit you got?

      There’s always going to be a little innacuracy on all wearables but if you are planning a very long run it need to be the most accurate possible. 

  4. It’s good to know that there are specific fitness wearables for marathoners that give inaccurate results. Thanks for the heads up.

    I have  a friend who has been joining marathon competitions and being a winner as well. Maybe she’s using a really reliable fitness wearable.

    I believe aside from wearing the right fitness watch, training consistently and living the right lifestyle are the best ways to become a winner in any marathon or just finishing up until the finish line would be awesome.


    1. Hey Marita, 

      The training is of course the base of your success during a marathon. Your body need to adapt physically and mentally. That will keep you in shape during the race and to not ”hit the wall” on the last miles. 

      A wearable should help you workout more efficiently and help you find your pace for race day. 

  5. Hi
    Thank you for sharing this article. I am really very interested in the marathon. So I have read your entire post. You nicely described which device I should use and which not. I think Apple 4 is the best option. So I will try it. I will share your post to them who are interested in Marathon.

    Thank you so much for your interesting post.

    1. Hi Monalisha, 

      It is a pleasure 🙂 

      The Apple Watch 4 Series is a great choice if money doesn’t kill you. It got enough battery life to last a full marathon (around 5-6 hours with GPS on). 

      If you want about 3-4 months the price will probably drop a bit. 

  6. Very interesting topic and I was glad to read that the Wearable I just purchased has a good review! I don’t run, due to surgery, but I try to get in as much movement as I can. Glad someone else thinks my purchase is a popular one in the industry. I look forward to  hearing more about fitness and all the gadgets that will help keep me on track! Thanks!

    1. Hi! Thanks for the warm reply. 🙂 

      What device you are using? There’s plenty of choice in the wearable industry and not only the most expensive are the best. I got a TomTom Spark3 and it works awesome. Sometimes you shouldn’t judge the book by his cover. he he !  



  7. Dear Alvaro,

    Thanks a lot for the informative and helpful post.

    Once in year in the city where I live we will have a marathon which is very popular and some of my friends do participate every year but I never participated. This year I am determined to give it a try but whenever I am in I am into it totally. So I am doing my research online for helpful tips and ideas. I found your insightful post and I got great insights from your post on which wearable devices we need to avoid.

    Indeed, Smart watches and activity trackers will be a greater help. As a team my friends and myself decided to buy best runners watch but to be honest the price are very high. Based on my research I came up with “Garmin vívosmart 4” which comes under our budget.

    Your article certainly made me think more on the subject. Nice article, I really enjoyed the content and in the manner that you presented.

    Much Success!


    1. Hey Paul, 

      If that can help someone I will be really glad! 

      You can try the TomTom Spark 3 of you are on a budget. 

      If you are a Garmin lover you should pay a little extra and get the Vivoactive 3



  8. Having the right wearable for when you are training is really important. While I don’t run long distances, I do like to know how far I’ve gone whether on walks or runs…

    The device I currently have is actually a FitBit Blaze so I’m not exactly sure on how accurate that is, but it seems pretty decent when comparing to my phones tracking.

    I’m actually interested in getting the latest Apple Watch, do you know how accurate that one is by any chance?

    1. Josh,

      Since your Fitbit Blaze doesn’t includes a built-in GPS, the accuracy is not so great (only using accelerometer /step count) for long runs that for sure. Unless you connect it via Bluetooth to a phone (with Location activated).

      The Apple Watch 3 and 4 are great watches but it is an awesome all around watch that does it all. I don’t suggest it of you are running long distances that need to be accurate. 

      DC Rainmaker did a nice in-depth testing with the Apple Watch 4

      and the accuracy was good but compared to a Garmin 935 or a Sunnto Trainer it was off by more than 250 meters. The other two models were only off by 3 meters or so. 

  9. Hi, I read your article very carefully. I am very excited to read your article because i have learn many important tips about training for a Marathon, 8 wearable that we should avoid.Thanks for writing this wonderful article. I never have used any of these but they seem interesting. This product is very helpful  for the people who preparing himself for a marathon.  This is very good post. Thank you very much for sharing this post. 

    1. Much Appreciated Jannatul! 

      Thanks for the good reply. 

      Let me know if you have any questions concerning a specific wearable. I’m here to guide you!!

  10. Thanks for this great review.  I figured most devices would have a margin of error but I’m surprised that the margin can be so high.

    I’m an Apple guy and had the Apple Watch series 1.  I loved it but the battery life wasn’t good enough for my use.  I actually skipped series 2 and got a series 3.  The battery issue was addressed and it now lasts me 2 full days on a single charge.

    I’m shocked that, although the series 1 only had a 1% error rate, the series 3 was at 13%!  You’d think, with the GPS chip, it would be much more accurate.

    I’m both saddened and pleased to know this information.  On the down side, I can’t trust what my watch tells me.  On the up side, I now know that.

    Thanks again,


    1. Thanks Scott! 

      The Watch 3 is a great watch (compared to the previous series). Still the problem with these intelligent smartwatches, it’s the battery life. Can someone help me??! 😛

  11. Hello, thanks for sharing this interesting and helpful article. My family’s friend is a marathoner. Every year he joins marathon competitions, but I never ask him what kind of wearables he uses. I will send him a message with a variety of devices, and I believe he will like your advice on Apple Watch Series1 or which ones to skip.

    1. It is definetely one wearable to avoid! ha ha ! Dont worry about Serie1, it is discontinued! Series 3 and 4 only now. 

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