Fitbit Charge HR and Surge mainThe Fitbit Charge HR and Fitbit Surge are now available to buy in the UK. They add complexity to the Fitbit lineup which also includes the Fitbit Charge, Flex, One and Zip.

The new Fitbit Charge HR includes optical heart rate technology for automatic wrist-based heart rate tracking all day (not just when you wake up) and during workouts to give a more complete picture of your health and fitness, and it includes heart rate zones to help you hit specific targets.

An Exercise Mode records workouts with the press of a button and provides real-time exercise stats on the display, as well as detailed exercise summaries and heart rate insights on the Fitbit dashboard via web or app. There are also notifications such as Caller ID which shows the caller’s name or number when a smartphone is nearby.

Automatic sleep detection monitors sleep quality and there is a silent, vibrating alarm.

The Fitbit Charge HR is water-resistant and has up to 5 days of battery life.

The Fitbit Charge costs £119.99.

The Fitbit Surge has all the Charge HR features plus built-in GPS giving it the ability to measure pace, distance and elevation. It can sync with mobile devices to show route history and workout summaries. it has a multiple sport mode, to classify workouts and view detailed summaries of exercises completed including heart rate and calories burned.

Battery life is rated as up to 7 days.

The Fitbit Surge costs £199.99.