Fitbit has announced the Alta HR, bringing heart rate monitoring to last year's slim and stylish Alta fitness tracker.

The new device introduces a slimmer and more compact version of the PurePulse technology found on the company's larger devices, such as the Charge 2, in order to retain the same design as its predecessor. 

The Alta HR is therefore still only 15mm wide, making it one of the slimmest fitness trackers on the market with heart rate monitoring. It has interchangeable straps, like the original Alta, and the older straps are still compatible with the new model.

Aside from the addition of heart rate monitoring, Fitbit is also bringing improved sleep tracking to the Alta HR, with some of its other devices following. The Alta HR will offer light sleep, deep sleep and REM data, along with tips on how to reach goals and explanations as to what each category means and how they correspond to activity goals.

FitbitFitbit sleep

In terms of other features, the Alta HR will offer the same as the original Alta. This means it will continue to track steps counted, distance travelled, calories burned and active minutes, while also offering SmartTrack for automatic exercise recognition and Reminders to Move. It will also deliver call, text and calendar alerts on its 1.4-inch OLED display.

Unlike the Charge 2, the Alta HR won't however feature Cardio Fitness Level, Guided Breathing Sessions, Multi-Sport tracking or Connected GPS, but it is said to have a seven-day battery life.

The Fitbit Alta HR will be available from April for £129.99.