Fitbit Charge 2 fitness band will track your pulse and help you, er, breathe better

Also incoming: Flex 2 for stylish but basic step and sleep tracking

Fitbit came up with a new twist on fitness trackers with the Fitbit Blaze. Now, it's returning to its more familiar approach: updating its existing bands. So it's au revoir to the Fitbit Charge HR and hello to the Charge 2. And ditto for the and more bog-standard Flex.

The Charge HR is effectively replaced by the Charge 2. Despite not having HR in its name, the Charge 2 does do pulse tracking.

As well as tracking your resting and active heart rate, the Charge 2 will attempt to give you a score for your overall fitness, by calculating your VO2 Max.

This is normally established by using bulky equipment to measure how much oxygen you breathe out when your body is pushed to its limits, in specialist labs. However, like a lot of recent fitness wearables, the Charge 2 will estimate it from just your pulse and general activity levels.

The great thing about this it is just one number that can be considered as a simple fitness 'score'. It's a very easy way to see if your fitness is improving, and whether it's better than your friends'.

Is it incredibly scientific? No it is not, but what Fitbit's made its fortune on is coming up with simple ways to see whether you're getting fitter, and this fits right in to that category.

Also on board: guided breathing sessions. These are two-and five-minute mindfulness workouts, where visualisations, animations and vibrational cues, "help you align each inhale and exhale with the guide, and find moments of calm throughout your day."

So that's nice. Yes, that does sound quite like bollocks, but Fitbit is adamant it can have real benefits to stress levels and even your blood pressure.

The new Charge 2 is broadly similar in appearance to the best-selling Charge HR, but the new, 1.5-inch display looks like a big aesthetic improvement, as does the option to swap out other interchangeable bands.

The low-end Flex has also had a spruce up, starting with a new band design that looks far plusher than smooth, rubberyness of the original, and is also 30% thinner.

Flex 2 now comes with SmartTrack, which automatically detects and starts tracking different fitness activities - walking, running, cycling - without you needing to remember to press 'Start'.

The Flex 2 is now waterproof too, so it will also track your lengths in the pool.

Both bands offer text and call notifications. The Charge 2 and Flex 2 are available for pre-order on Fitbit.com now and will be in stores from September and October respectively. Pricing? Yes, there's quite a lot of that…

Charge 2 £129.99 in black, blue, plum or teal. Replacement standard bands £19.99, leatherbands £59.99, special edition in gunmetal and rose gold £149.99

Flex 2 £79.99 in black, lavender, magenta or navy. Replacement bands £29.99 for a triple pack. Bangle accessory in gold, rose gold £79.99. Silver stainless steel £69.99. Pendant in gold £79.99. Pendant in silver stainless steel £69.99.

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