Over the past few weeks it's become clear that the latest crop of optical heart rate sensors just aren't up to task.
That might not come as a surprise to the more cynical of Wareable readers, but let me justify my thinking.
When Fitbit and Apple started putting heart rate tracking on the wrist, I naturally wasn't convinced – and nor were the likes of Garmin and Polar. Those big guns of the fitness world were staying clear of Mickey Mouse gimmicks, and kept their focus firmly on the chest strap.
Then came Mio. When we spoke to Liz Dickinson, who's credited with inventing optical heart rate tech, she rubbished the work of Fitbit et al, claiming Mio's was the only capable technology.
And the tech industry responded.
That led me to believe, mistakenly, that the technology was ready for prime time. I felt that if Garmin was finally backing the technology, it must be good enough – but that's not the case. And while I'm not an athlete that relies on my workouts being fixed within narrow and specific zones, once I know that something's not accurate, the data becomes junk to me.
And the most telling evidence comes in the form of a product that's not even been released yet.
Under Armour's new band comes bundled with a separate heart rate monitor designed for exercise – a clear admission that the technology isn't capable of cutting through the noise and movement experiences during high intensity workouts.
"We're being pragmatic about what you can do on the wrist and what you can do on the chest. We want to appeal to athletes," said Claude Zellweger, VP of Design at HTC, which created Under Armour's technology.
And while that's refreshing to hear, it confirms what we already know: if you're serious about your data, then the latest optical-toting wearables aren't up to scratch.
So should you disregard these devices altogether? Absolutely not. The Garmin Forerunner 235 is a fantastic device, which will pair with ANT+ chest straps for those HIIT sessions. It's not the technology's failings that sits uncomfortably with us, it's that Garmin and Fitbit aren't being as open as Under Armour about what their tech can and can't do.
The Garmin Forerunner 235, for example, utilises its optical tech to great effect when you're not working out. And if you pair with a chest strap for a HIIT sessions you'd have an incredible set of fitness data – it's just a shame that Garmin never really mentioned that.