Forget AirPods Pro: These earbuds measure your heart rate for $50 less

Soul Blade
(Image credit: Soul)

If you're a fan of both fitness and wearable tech, there's a good chance you own both a pair of earbuds and a fitness tracker. 

The tracker, or perhaps a smartwatch, will record your exercise data so you can monitor your progress and improve your technique, while the earbuds provide audio entertainment in the form of podcasts or a workout playlist. 

However, the Soul Blade wants to offer both devices in one package.

Retailing for $199 and set to be released around the end of March, the Blade is the first pair of true wireless earbuds with a built-in heart-rate monitor and "personalized AI voice coaching" to help you run at your best.

This is an evolution of Soul's Run Free Pro Bio earbuds, released in 2019. Those offered a similar feature set but were not true wireless like the Blade is. 

Soul initially showed off the Blade last year, as well as launching an IndieGoGo campaign to help fund it, but the retail release is now scheduled for some point in Q1 of this year.

You access all the Blade's special features from the Soul Fit companion app. It's through here that you can check the measurements taken by the Blade, as well as issue challenges to any other friends with the app to be the first to reach certain milestones.

What the Blade monitors specifically are "gait parameters," the set of measurements relating to how you walk or run. It does this by tracking the movements of your head, which you calibrate before starting a run in a quick two-step process. 

Once your exercise session is complete, you can look over the data in the app. This includes information on run consistency, stride distance and width, how hard your step take-offs and landings are, and, of course, your heart rate, the Blade's signature feature.

If your form needs some adjustment when on a workout, the app will let you know via instructions played through the earbuds, which will tell you the problem and what you need to do to fix it. 

Following the app's advice should making your running more efficient, and hopefully prevent potential injury. If being coached by an AI voice sounds grating, then there is an option to switch it off.

On the buds themselves are touch controls, which let you access music and call controls with various numbers of taps. You'll also find four different sizes of c-shaped earpieces in the box, the unusual shape preventing them from shaking loose while you're working out.

Soul Blade

(Image credit: Soul)

There's also limited noise canceling when speaking via the dual microphones on either earbud, making it much easier for whomever you're talking to on the other end to hear you. 

There's a "transparent audio" mode on offer, similar to products like the AirPods Pro. It lets you block out sounds around you when you want, but can pipe in sounds through the microphones instead if you want to keep track of your surroundings, handy if you tend to go out running in busy areas.

Even the Blade's more mundane features are impressive. It offers IPX7 water resistance so you needn't fear a sudden downpour damaging your buds. 

There's an impressively long battery life on offer, with the buds lasting 5 hours per charge (6 hours with the fitness tracking switched off), and the case offering a total of 96 hours playback time over 15 charges. 

The USB-C port on the case even allows you to top up another device with the built-in 2,580mAh battery if you're caught low on power.

You may be skeptical of why you'd want fitness tracking on your earbuds when you have a perfectly capable smartwatch. Soul's answer to this is that earbud-based tracking can be more accurate for certain measurements because your head is always aligned with your body's center of mass, unlike your arm that moves independently. 

The company does admit, however, that you're unlikely to wear the Blade for sustained periods of time as you would a wrist-mounted tracker.

At $199, the Soul Blade costs a lot more than any of our current best sport earbuds. However, it offers a lot more, too, including a detailed analysis of your runs and an impressive battery life. 

We'll need to try out the Blade for ourselves when it finally ships, but on its face at least, Soul might just have the ideal pair of earbuds for runners on its hands.

Richard Priday
Assistant Phones Editor

Richard is based in London, covering news, reviews and how-tos for phones, tablets, gaming, and whatever else people need advice on. Following on from his MA in Magazine Journalism at the University of Sheffield, he's also written for WIRED U.K., The Register and Creative Bloq. When not at work, he's likely thinking about how to brew the perfect cup of specialty coffee.