External heart rate monitors and Spark

bigmazungo Registered Users Posts: 4
Apprentice Traveler
edited January 24 in TomTom Sports
While experimenting with my tom tom spark I noticed that the watch is able to detect what it calls "external" heart rate monitors. Given the active threads on the strengths and limitations of optical heart rate measures, is it a good response to use a external monitor in collaboration with a tom tom watch? My heart rate monitor was part of the adidas "Micoach" kit so are there technical issues and considerations insofar as using and external monitor and fit/compatibility with the tom tom spark or are they, as I suspect, pretty much the same specification wise?


  • tfarabaugh
    tfarabaugh Posts: 16,936
    External straps are valuable for certain exercise but have their own inherent limitations as well. Wrist based sensors are greatly impacted by forearm tension and flexing, so any sport that involves that (weight lifting, rowing, cycling - when you bear down on the handlebars) will be impacted as you are compressing the blood vessels and reducing blood flow. For these activities I use a strap. For other activities like running, indoor cycling, cardio, etc., I find the wrist based sensor to be fairly accurate when compared to a strap (you may see issues with spikes in HR at the beginning of a run in particular if you are not warmed up as the watch grabs the strongest signal, which may actually be your cadence, not your HR).

    As to technical considerations, any HR strap must be BT+ which I am fairly certain the miCoach was not. In general the cheaper the better seems to be the case as price seems to not be a factor as the cheaper ones often seem to work better than the expensive ones. This is due to the fact that cheap models are more likely to use the base BT protocols and not customize them for advanced features or settings like more expensive models do (and there is no way of knowing if a manufacturer has tweaked the protocols to take them out of compliance). The BT standard is in such a way a 'standard' that it can be widely interpreted with different settings for buffer sizes, time outs, profiles, protocols, antenna configurations, etc.. TomTom cannot change their code every time a manufacturers messes with the BT coding. This is a case where paying more will not increase the chances of connectivity, it may actually decrease it. There are thousands of models out there so there is no way for TT to test them all and since the manufacturers often tweak the BT settings there is no way to know upfront if a peripheral will work or not.

    I hope this helped answer your question. If so, please mark it as a solution so others can look for it if they have the same question.