
The 920XT will, this month (Dec 2015), be firmware-updated to support the new running dynamics that were recently introduced for the 630 and even more recently promised for the Fenix3.
I’m assuming they will work with any old HRM-RUN and not just the special new HRM4-RUN. We’ll see.
This will also require a firmware upgrade to your HRM-RUN, so keep that handy when prompted to do a firmware update.
Don’t get too excited tho, the new special metrics are not that exciting really. And before you ask NO YOU DON’T GET THE PHYSIOLOGY measurement of LTHR, etc as found with the 630. That will probably be added in early 2016.
? => Polar’s ‘Advanced Running Dynamics’
Last Updated on 30 November 2015 by the5krunner

tfk is the founder and author of the5krunner, an independent endurance sports technology publication. With 20 years of hands-on testing of GPS watches and wearables, and competing in triathlons at an international age-group level, tfk provides in-depth expert analysis of fitness technology for serious athletes and endurance sport competitors.
Any news regarding if it works with the “old” HRM-run or only on the new HRM4-run?
yes new run dynamics work with the old/original hrm-run. firmware update must be performed.
Ok, thanks! So what’s the difference between the “old” HRM-run and the “new” HRM4-run then? (Except the looks)
I don’t know what is inside. probably is different hardware ie its prob same as the hrm-tri but with bits turned off eg caching. but the result of turning the bits off on the firmware is that the visible functionality is the same as the original HRM-RUN. as you say it looks very different. there’s even 2x strap version with the original hrm-run, the fancy lined strap seems v good to me.
Ok, got it!
Great blog by the way, keep up the good work!