Triathlon Training NZ

Why I DON’T like Optical HR Monitors

I’ve been meaning to write about this for a wee while. I’ll be up front: I DO NOT LIKE OPTICAL HR MONITORS.

I don’t care if they are Fitbit or Garmin or some other brand. The technology to do it at a reliable and accurate level is not there (yet). Yes, I roll my eyes and my head tips back when a client tells me “I’ve bought a Fitbit for heart rate training’.

WHY? If you are a client of mine and you are thinking of buying a major training tool, talk to me before doing so and I can advise you on how best to invest your money.  This applies whether it is a heart rate monitor, or some other tool or training equipment. The best marketed items, aren’t necessarily the best items on the market.

OK, I’ve got that off my chest (excuse the pun). I’ll go into why I don’t like them shortly. But before I do that I’ll tell you why I like them.  Yes, I know that goes against what I’ve just written, but they do have some good features and pros.

They are good for sedentary people. They are good tools for encouraging sedentary people to get active.

But if you are a client of mine, you are NOT sedentary, just by the virtue of what you are training for.

So regardless of what you are training for, if you are training with me and you have an optical Heart Rate (HR) monitor, put it on TradeMe or eBay and use the money you get to buy a Garmin, TomTom or Polar or something that is not an optical HR monitor.

Why Don’t I Like Optical HR Monitors?

Standard HR monitors pick up electrical signals from the heart each time it beats. Boom, that is how you measure heart rate. Reliable, as long as the signal from the strap to the watch isn’t picking up interference from some other source (which is possible).

Optical HR monitors detect changes in light shining through your skin from the capillary bed underneath. WOW, seriously can it do that? Yes it can, but what happens when the skin is dirty with sweat, or mud, or the watch is bouncing around as you run? That is what makes it inaccurate.

Don’t just take my word for how inaccurate they are:

But isn’t this the same technology they use in hospitals? Yes it is, but the difference is a nurse that puts it on your finger, cleans you finger with an alcohol swab and you are doing nothing more than lying in your hospital bed, not out and about running through the forest or something, expecting the monitor to remain error free.

On top of this, FitBit have been sued about the claims they make about the accuracy and reliability of their product:

If you would like further advice feel free to contact Coach Ray.

Coach Ray is the Head Coach & Director of Qwik Kiwi – Endurance Sports Consultant and is a prominent triathlon and marathon coach in New Zealand.

Coach Ray specialises in assisting first timers and recreational athletes to achieve their sporting goals. He can be contacted at and 021 348 729.

Share this post so your friends can benefit as well.

4 Replies to “Why I DON’T like Optical HR Monitors”

  1. Are the Garmin watches that have built in HR monitors accurate? I am wanting to get hr data when training and I don’t like the chest straps.

    1. Hi Lynaire,

      Unfortunately the technology involved with ‘reading’ your heart rate without a strap leads itself to inaccuracies (for a number of reasons).

      The only reliable way to get an accurate heart rate reading whilst exercising with detecting the electrical impulses of the heart and for that you will need a Heart Rate (HR) strap.

      I know a number of females dislike wearing a strap due to the placement of it very close to their sports bra. You can still get reasonably reliable HR results by wearing your strap a bit lower down below the bra (rather than under the bra).

      Further more some straps are more comfortable than others. I personally don’t like the Garmin Premium strap and link an old ‘standard’ Garmin strap with my Forerunner, as that is more comfortable for me. Other people prefer the Wahoo Tickr and connect that with what ever technology they primarily use.

      Have a good look around, and see what else is available. It’s a case of personal preference. It’s even better if you can borrow a friends to try before you buy and see if it causes what ever problems you didn’t like about your old strap.



  2. Ray,

    I’m totally on board with you on the HR Monitors. I’m looking to get a new, I currently have a Garmin Forerunner 205, which still works great, but it’s time for an upgrade. I would love to have the Fenix 3, but still can’t get over paying that much. What do you recommend? I want to stick with Garmin.


    1. Hi Adam,

      The Fenix 3 with the Heart Rate strap is a great model. What I recommend will depend on what you want to use the watch for and what features are important for you and your coach (if you have one). If it is for running only then you can probably relay on one of the mid-range Forerunners.

      Feel free to PM me through Facebook and we can chat more.



Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.