Once upon a time the only way for us average, amateur fitness types, to track our heart rates in real time was to stick on a chest strap or pay to visit an expensive lab and be wired up like a science experiment. But now, thanks to a little thing called an optical heart rate sensor, we now have a choice.
We can, if we so desire, ditch the much-maligned torso ticker tracker and have our running watches and fitness bands monitor our bpms instead.
Essential reading: The best heart rate monitors
First it was Adidas, Mio and TomTom that tried to tempt us to drop the strap and fasten our watches; then the likes of Apple and Samsung followed suit. Now even the stalwarts of the strap, Garmin and Polar, have joined the optical revolution. But the chest versus wrist debate still has opinions divided.
Which is most accurate, more convenient and a better fitness companion? Our fitness tech expert Kieran Alger weighs up the pros and cons and reveals whether you should be strapping on a watch or a chest band.
Purveyors of wrist-based technology go a long way to convince us otherwise, but there's a great deal of consensus among sports professionals that the chest strap is still your best bet for near-absolute accuracy in heart rate tracking.
Both technologies use algorithms to convert what they read into estimated heart rate but the theory is that, because chest straps track closer to the heart, they tend to be more reliable – provided you've got a good wet contact between the pads and the skin.
Must read: Our real world heart rate monitor test - Fitbit, Basis, Mio
Because they're on your wrist, optical heart rate sensors actually read your blood flow further from the source and accuracy can also be reduced by light leaking in and affecting the sensor.
Winner: Chest strap
The chest strap gets a hard time when it comes to comfort. Anyone who's ever run for more than an hour wearing one will attest, they can get a bit chafey.
In order to ensure you've got that essential good contact there's also a tendency to wear them tight, which can feel restrictive and affect your breathing, psychologically at least.
Guide: How to choose the right heart rate monitor
It's also true that wrist-based heart rate watches tend to need to be done up tight on the wrist and can be uncomfortable over long training sessions but on the whole, the watches offer a happier fit.
Also we need to address The Boob Problem. Let's make one thing clear, I don't have boobs. But I have spoken to a lot of people who do and, more often than not, they only have negative things to say about chest straps.
Ok that's not actually a word but chest strappers will be all too familiar with what it means. You get to the gym and dig around in your bag only to find your HRM is nowhere to be found.
You're sure you put it back in after last night's session but then you did also empty out your gym kit and there's a good chance it'll be lying sweatily on top of your wash basket at home.
You're far less likely to forgetting that watch you wear all the time. Of course, this is all null and void if you have a watch you only use for working out or in fact if you forget to charge it.
HRM chest straps rely on old school watch batteries and while battery life can vary – something like the Polar H7 will give you a quoted 350 hours of tracking - definitely out lasting all optical heart rate watches on the market.
However, it's vital to remember to unclip it the unit from the strap. Fail to do this and your chest strap will sit in your bag or drawer having the life sucked out if it.
Optical heart rate monitors, on the other hand, will only give you half a dozen sessions or so, depending on how you use them when you're not training.
More frustrating is that almost all of them have their own unique charging cradle that means you either have to remember to charge them at home overnight or cart the charging cable with you wherever you go. Both of which you will almost certainly forget to do at some point.
When it comes to the nasty odours, chest straps get a bad rep. That little strip of fabric soaks up your blood, sweat and tears and, let's be honest, rarely goes into the wash. Give it six months and this little sucker starts to smell like a French cheese factory.
But, and there is a big but here, you only wear it when you're also getting worked up and stinky so who cares?
The optical heart rate watch on the other hands gets worn all day long and is quite capable of gathering its own particular pungency that's right there on your wrist for anyone unlucky enough to encounter your wafting hands.
Dispute their accuracy if you like, but wrist-based trackers almost always find a pulse. Provided you've got one, the optical heart rate sensors will pick it up and display this piece of tech success conveniently where you can see it.
In contrast, Bluetooth chest straps don't always hook up seamlessly to your smartphone or the watch you're using. The worst thing here is that when it fails you're not quite sure if it's the Bluetooth playing silly buggers or the battery in the sensor has called it quits.
What ensues is a period of Sherlock Holmes detection to decipher what the hell is happening. And all too often the case remains unsolved.
HRM chest straps can offer a cheaper way to monitor heart rate, particularly if you opt for a Bluetooth device that'll partner with a range of fitness tracking apps to give you a sweet of insights that can match a lot of the cheaper watches.
You can pick up a Bluetooth HRM chest strap like the Wahoo TICKR for £49.99 where as even the cheapest optical heart rate watch will set you back £99 plus.
Chest Strap HRM vs Wrist OHR: Verdict
For those of you who've been keeping score you'll notice the contest has ended all square. That's just a cop out right?
Well, yes and no. I'll come clean, my preference is for the chest strap but then I'm concerned with accuracy above comfort. That's not true for everyone. Fitness is personal and the most important thing is to find the tools that work best for your own workouts.