Silicone Bracelet Measures ‘Heart Interval,’ Tells You How To Train


Most fitness devices simply measure movement through the day and night with an accelerometer. They crunch data collected through algorithms and give you feedback about your lifestyle.

The to-be-released Reign by Jaybird LLC “promises to disrupt the athletic wearables market,” the company touts, because of new ways to measure and interpret your body’s biometrics.

It has a “heart rate variability” monitor that measures the time between heart beats to the millisecond. It also “learns” about you — your sleep patterns, heart rhythms and daily routine — to predict when is the best time for you to work out and with how much intensity.

This may be the biggest differentiator about the Reign. Using lots of data (explained below), the Reign will give you a “go score,” which basically means it’ll tell you, quantitatively, how you feel and if your body is ready for a hard workout or just a gentle jog.

The “sleep” screen also gives advice, telling you how many hours you should sleep the coming night after learning about your habits and how they affect your heart interval.

I traveled to Salt Lake City this week to visit Jaybird’s headquarters and see the Reign for myself. I sat down with sports scientist Ben Wisbey, who walked me through the functions and helped me fit one to my arm.

The Reign is a soft silicone band. It looks simple, either black or white with a silver strip along the center. Two magnetic clasps secure it around your wrist.

A removable “pod” sits inside the band. This is the brain of the device, which can be removed to attach to an included “sport” band (no clasps, just stretchy silicone) or a leg band used for cycling.

You wear the Reign all the time, day and night. Upon waking, you place your finger on the metal strip on the top of the device for two minutes while it measures your heart interval. Using the information it gains during these two minutes, the Reign tells you how hard to work out that day.

A note on the “heart rate variability” measurement. This is different than simply heart rate. While heart rate gives you a number of beats per minute, the Reign measures the variability in the amount of time between beats. More variability is good, Wisbey said, and it means you are healthy and ready to train — basically that the heart responds quickly to external stimulus like a smooth revving engine.

Reign gives all feedback through its Bluetooth link with your cell phone and an app. The app provides information about what you’ve done (Activity and Sport) how you’ve slept (Sleep) and what you should do (Go Zone).

Interestingly, the company claims it can tell what sport you’re doing (swimming, running, surfing, climbing) just by the motion it detects with the accelerometer.

I got to try the band in Utah. Unfortunately, the app won’t be available for testing for another week, so it will be a few days before I can speak to the band’s effectiveness and accuracy.

However, if it lives up to the company’s promises of telling you not just what you’ve done, but what you should do next, the Reign could be one of the more useful bands on the market.

Reign will retail for $200 when it hits the market on Oct. 26, so it is on the high end price range of activity trackers. I’ll be testing the app and other functions as soon as the beta becomes available. Stay tuned!

Sean McCoy

Sean McCoy is the Editorial Director of GearJunkie, and 5+ other All Gear websites.

He has been writing about hunting, fishing, trail running, camping, skiing, and more for 15+ years.

Prior to GearJunkie, he was the chief photographer for the Virgin Islands Daily News and former Editor In Chief for GearJunkie. Based in Denver, Colorado, McCoy is an avid trail runner, camper, hunter, angler, mountain biker, skier, and beer tester.