TomTom Runner Cardio review

When the TomTom Runner and TomTom Multi-Sport GPS watches arrived last year, they didn’t exactly set the fitness technology market on fire. They were decent enough devices, but they didn’t offer anything new, and failed to make a strong enough case for themselves against the established competition. But that’s all about to change, with the arrival of the TomTom Runner Cardio.

TomTom’s latest GPS watch certainly couldn’t be accused of bringing nothing new to the market; in fact it could quite accurately be described as ground breaking.  So what’s so special about the TomTom Runner Cardio?

TomTom Runner Cardio heart rate monitor

If you take your training seriously, you’ll already be well aware of the benefits that a heart rate monitor (HRM) can bring. Training with an HRM allows you to monitor and dictate the effort of your sessions, as well giving you valuable insight into your fitness levels over time.

 If you find that you’re running the same route, at the same pace, but with a reduced heart rate, you know that your cardiovascular fitness has improved, and there are far less simplistic metrics to apply when you have live and historical heart rate data to work with.

Traditional heart rate monitors take the form of sensors that attach to a chest strap. The strap will be equipped with electrodes that touch your skin and send the data through to the sensor, which then transmits that data to your sports watch, cycle computer, smartphone or even gym equipment.

There’s nothing wrong with the traditional method – it works, and the inconvenience of having to wear the strap is far outweighed by the benefits of the data collected. But what if you could get a constant, accurate measure of your heart rate without the need for a chest strap and wireless sensor? Well, thanks to TomTom, now you can.

As it’s name hints, the TomTom Runner Cardio’s party trick is that it has a heart rate monitor built right into the watch, and that’s something that many runners – ourselves included – are very excited about.

TomTom Runner Cardio how the heart rate sensor works 

The TomTom Runner Cardio measures your heart rate differently to the way a chest strap sensor does. Instead employing a type of electrocardiography to measure your heart physically beating, the Runner Cardio uses an optical sensor that’s mounted in the rear of the watch.

Accompanying that sensor are two very bright LEDs, which shine through the surface of the skin. The sensor then measures any changes in skin colour, since skin tone changes ever so slightly when your blood pumps through it. By tracking those changes in skin tone, the Runner Cardio can calculate your heart rate.

This type of optical heart rate measurement isn’t new – Withings employed a similar system in its Pulse activity tracker last year. In fact some smartphone apps utilise the handset’s camera and flash to achieve the same results. The difference is that all these other devices have only offered a “spot” heart rate measurement, rather than a continuous one, making it a far less compelling feature for anyone who’s serious about their training.

To maintain that continuous heart rate measurement, the Runner Cardio needs to be kept pretty tight to your skin, but not uncomfortably so. To ensure a solid connection, TomTom has designed a new strap, which employs a three-prong buckle, along with pins that hold the excess tongue in place. We found that the Runner Cardio was very comfortable to wear, even on long runs.