Fitbit says the Charge 4 can last up to seven days on a charge, but I barely made it to day four before having to plug it in. The only downside about having GPS on the Charge is that it'll gobble up your battery a lot faster than on the Charge 3. I can see this being a good training tool if you're looking to break your personal record in a race.

I realized I'd been overestimating my effort and it was helpful to have the Charge nudging me to get out of my comfort zone. I had to push myself much harder than usual to get my peak heart rate alert to pop up on the screen (you also get a buzz on your wrist when you reach each zone). The Charge 4 adds real-time heart rate zone notifications so you can take action during your workout. After a workout you can log into the mobile app and see how long you were in fat burn, cardio or peak. The goal is to have 150 active minutes logged by the end of each week, but you can increase or decrease the target based on your fitness level.Ī few years ago, Fitbit started breaking out heart rate data into training zones for each activity, based on age and weight. The Charge 4 has added a new metric called Active Zone Minutes, which uses your heart rate zones to determine the intensity of your workout. Like the Charge 3, it's also hard to see the screen in direct sunlight. The only time the lag really bothered me was while I was running and wanted to quickly glance at my stats without taking my eyes off the road. The touchscreen isn't as responsive and it takes a few seconds to light up when you raise your arm to wake the screen, but I eventually got where I wanted to go. Instead, you control the Charge 4 with a combination of the touchscreen and by pressing the left side of the tracker to navigate settings.

, and it also does away with physical buttons. The screen can only display in black and white, but I like that it's nearly half the size of a traditional smartwatch, such as the , the new version doesn't look much different - it's just the tiniest bit bulkier on your wrist. The $150 Charge 4 (£130, AU$230) is a tracker I will happily wear 24/7 thanks to its sleek, understated design. There are plenty of great wearables for athletes, like the Garmin Forerunner 945 and Suunto 3, that have way more fitness chops than the Charge 4, but they're not the most fashionable. Shorter battery life than the Fitbit Charge 3

Fitbit charge 4 charger