Some more reports on social media on the reliability of the new Garmin 225’s heart rate.
Generally, it seems good and accurate to most people. However, one chart, below, shows the perennial problem with chest straps of dropouts seems to be periodically occurring with some users.
Martijn shows the following on a tempo run (at 01:06:40):
I’m somewhat surprised as the MIO sensor (which the 225 contains) has always been very reliable for me over the numerous MIO devices I have.
anyone with other experiences?
Last Updated on 14 January 2026 by the5krunner
Reader-Powered Content
This content is not sponsored. It’s mostly me behind the labour of love, which is this site, and I appreciate everyone who supports it.
Support the site: Follow (free, fewer ads) · Subscribe (paid, ad-free) · Buy Me A Coffee ❤️
All articles are written by real people, fact-checked, and verified for originality. See the Editorial Policy. FTC: Affiliate Disclosure — some links pay commission. As an Amazon Associate, I earn from qualifying purchases.
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.
I got so frustrated with the optical HR monitor on my 225 last night that I’m on the web right now searching for what to do about it. Most of the time it’s good, but sometimes I’ll be pushing up a hill like last night, my heart pounding, and I check, only to find it’s reading 87 “no zone”. What the heck?? The strap was so tight it was twanging the nerve in my wrist, so I loosened it a bit, but still below 90. Ten minutes later I looked and it was at 135, so at some point it fixed itself, but not before a lot of ineffective fiddling and cursing.
Maybe not so tight. Maybe spin round wrist. If bend wrist u will affect blood flow
Thank you for the suggestions. The only one I didn’t try is flipping it around to the watch face is against the inside of my wrist rather than the outside; I’ll try that.