New Fitbit Charge HR and Surge add heart rate to the equation (pictures)

Have you been wondering what Fitbit's been up to? After a long hiatus the company has announced three new wearable fitness gadgets: the Charge, Charge HR and Surge (left to right). We'll explain them for you.

The Fitbit Charge HR will cost $150 in the US, £120 in the UK and $180 in Australia, and won't arrive until early 2015. It measures your heart rate continuously.

An optical heart-rate sensor on the back distinguishes it from the Fitbit Charge, which is a pedometer and sleep tracker arriving this November.

A more watch-like buckle keeps the Charge HR on your wrist more securely than the old Fitbit Force.

The Charge HR lasts up to 5 days while measuring your heart rate all day and night. It can track your baseline heart rate and use it to find workout-based target heart-rate zones.

The Fitbit Charge HR in purple: it'll be available in several colors.

The Fitbit Surge is a more expensive workout smartwatch. It costs $250 in the US, £200 in the UK and $300 in Australia, and, like the Charge HR, won't arrive until  early 2015.

The Surge also has continuous heart rate tracking, but adds an LCD touchscreen and built-in GPS to track workouts and runs.

The Surge can receive text messages and caller ID from compatible iPhones, Android and Windows phones. A music control function also plays and skips tracks on your phone via Bluetooth. But the Surge won't get other notifications.

A standard watch band fits securely, but the Surge's design is slightly wider than other watches.

These side buttons are used to start and stop workouts.

The fitness-watch market's getting crowded, but the Surge aims to compete with more dedicated sports trackers, as well as fitness watches like the Basis Peak.

Will early 2015 be too late for the Fitbit Surge, or perfect timing? Stay tuned.

A look at the Surge's optical heart-rate tracker.

Fitbit's app will be redesigned to take advantage of these new devices.

New achievements and challenges are part of the redesigned app.

A look at how heart-rate data is displayed on Fitbit's app: all-day heart-rate progress can be charted and synced.

The Fitbit Charge, coming out this fall, is a replacement to the discontinued Fitbit Force. Like the Force, which went on sale last year, the Charge tracks steps, elevation, and has automatic sleep tracking.

A newly designed band aims to attach more securely (the Force had a habit of flying off wrists). The material's also been changed to avoid skin rashes.

It looks and behaves much like the old Force, with some additions: improved automatic sleep tracking, and caller ID from compatible Windows phones, Android phones and iPhones. The Charge costs $130 in the US, £100 in the UK and $150 in Australia.

The Fitbit Charge and Charge HR side by side. They really do look alike. The Charge HR doesn't cost much more, but won't arrive until next year.