Wearable tech firm Fitbit has launched its latest fitness wristbands – Charge 2 and Flex 2.

Charge 2 features a heart rate tracking tool, has a larger display area and allows for interchangeable bands, while Flex 2, which is swim-proof, features a removable tracker, allowing users to track all-day activity, exercise and sleep.

Charge 2’s heart rate tracking tool makes it easier to maximise workouts, better track calorie burn and get a better picture of overall health. With the heart rate tool, users can find out their cardio fitness level and score. The product also offers a personalised deep-breathing mode called ‘Relax’, which offers two- and five-minute breathing exercises. Research has shown that breathing exercises can help with stress, anxiety and lower blood pressure.

Flex 2 is a swim-proof fitness wristband and is water resistant up to 50 meters. It tracks pool swims including laps, duration and calories burned in the Fitbit App. Its SmartTrack automatically recognises workouts, such as walks, runs, rides, elliptical, sports, aerobic workouts, and swims.

Earlier this year, analysts Juniper predicted that by 2019, fitness wearables will be used by approximately 110 million people worldwide.

Fitbit forecasts revenues in the range of $490million to $510m for the third quarter of this year. Earlier this month, Fitbit reported Q2 revenues of $586.5m - 46% year-on-year growth. It sold 5.6 million devices during the Q2 period. During the three months, it launched Chinese, Japanese and Korean language versions of products into their respective markets.

James Park, Fitbit co-founder and chief executive said: “Over the past nine years it has been our ability to innovate on both design and utility, and our deep understanding of what consumers want that has made us the leading global wearables company.”