The rumors were true: Fitbit isn't done for the year. The company just announced two new fitness trackers that add second iterations of existing products to its lineup: the Charge 2 and the Flex 2. The Charge 2 is an improved Charge HR, now with new features, a larger display, and interchangeable bands, while the swim-capable Flex 2 is an upgraded Flex with a completely new design that focuses on versatility.

Let's start with the Charge 2: its biggest physical improvement is the 1.5-inch display that replaces the Charge HR's small, narrow screen. It's like a wider version of the Fitbit Alta's display, finally big enough to show the time at the top and tap-to-scroll stats beneath it. Those stats include steps, heart rate, active time, and more. The Charge 2's bands are interchangeable, so you can swap the silicone, active band for more fashionable leather and jewelry-like bands. However, since the Charge 2 is just a wider version of the Alta, its overall attractiveness is in the eye of the beholder.

The Charge 2 has new software and tracking features that the Charge HR doesn't have. Its connected GPS lets it pair with your smartphone's GPS to map running routes and get better distance calculations, while its interval workout mode lets you to customize routines that alternate bursts of intense exercise with periods of low-intensity activity. The Charge 2 also has reminders to move, while calling, texting, calendar alerts, and activity profiles are accessible from the band's display. These profiles let you quickly track your most-completed exercises, like running, walking, biking, Pilates, and more. You decide which appear on the band and which don't.

Fitbit's Surge has these activity profiles as well, but the Charge 2 is the only other Fitbit product they have come to since. Like most other Fitbit trackers, the Charge 2's SmartTrack feature automatically knows when you're doing an exercise, such as running, and logs it without action needed from you.

Two new features make use of the Charge 2's embedded optical heart rate monitor: estimated VO 2 max and Relax sessions. VO 2 max is the maximum rate at which oxygen can be used by your body during intense exercise, and it's typically measured in a lab while someone is connected to numerous machines. However, a few heart rate-connected Garmin and Polar devices can also measure VO 2 max, so it was only a matter of time before companies like Fitbit incorporated that metric into their devices.

Fitbit's Cardio Fitness Level score is an estimate of your VO 2 max. I'm glad that the company calls it an estimate for a few reasons: first, the score is not your true VO 2 max score, but rather a translated number that Fitbit uses to place you on a leveled scale compared to others of your same gender and age. Second, the score isn't exact because VO 2 max is dependent mostly on oxygen intake and heart rate; Fitbit has no way of truly measuring your oxygen intake. Wrist-bound heart rate monitors are prone to more inaccuracies than chest straps due to placement and user error (like wearing the device too loose or too tight).

Valentina Palladino

Valentina Palladino

Valentina Palladino

Valentina Palladino

Relax sessions also use the heart rate monitor. They guide you through two-minute breathing exercises to control stress levels. A Relax session is initiated on the device's display, and it uses small animations to get you to inhale and exhale deeply over the course of two minutes. A number of apps encourage this kind of breathing behavior, but the Charge 2 is the first Fitbit device to incorporate Relax sessions.

The introduction of the $150 Charge 2 makes me wonder about Fitbit's most expensive and feature-rich product, the Surge fitness watch. At $250, the differences that set the Surge apart from the Charge 2 are design (it's slightly larger, with no interchangeable band options), a built-in GPS, smartphone music controls, and slightly longer battery life (seven days, compared to the Charge 2's five days). I wonder what Fitbit plans to do with the Surge, now that the company has the Blaze "smartwatch," which is clearly positioned as the most fashionable Fitbit device, and the Charge 2, which has so many Surge features. Some athletes will always demand onboard GPS, and while I hope Fitbit doesn't abandon the Surge, it needs some sort of update in the near future to keep it relevant among newer, flashier devices.

The other new device, the $99 Flex 2, is a slimmer, more fashionable redesign of the original Flex. The device itself is about an inch in length and 30 percent thinner than its predecessor, and it can be worn on silicone bands, shiny bangles, or long pendant necklaces. With its multi-light communication system (different lights on the device shine to show alerts, notifications, and more), it's similar to Misfit's Ray tracker, which can also be worn multiple different ways. In terms of style, the Flex 2 would be the most versatile device in the Fitbit family if not for the Alta, which has accessories from the likes of Tory Burch, Vera Wang, and Public School.

Aside from the style perks, the Flex 2 is swim-capable in up to 150 feet of water. Since most other fitness companies already have at least one device that tracks water exercises, it's about time Fitbit made a swim-tracking device. Metrics such as laps show up in the Flex 2's Fitbit app, just like any other trackable activity. Like the Charge 2, the Flex 2 has a battery life of about five days. Call and text alerts are noted via its light system.

The Charge 2 and Flex 2 are solid additions to the Fitbit family, but they also feel like Fitbit is playing catch-up with its competitors. None of the features in these two devices is unique to Fitbit. But the company has been experimenting with different types of wrist-bound wearables with varying features—namely the Blaze, which occupies a weird spot in the wearable market—likely with the hope of finding which devices speak to the masses the most.

The $150 Charge 2 and the $99 Flex 2 will be available in the fall before the holiday shopping season begins.