Not only does the fully waterproof Vivosmart 4 have Garmin's redesigned Elevate heart-rate sensor, new abnormal heart-rate alerts, VO2 max, stress tracking and activities for walks, runs, strength training, pool swims, yoga and more, but it introduces a new wrist-based pulse ox sensor.
Garmin says that sensor gauges your blood oxygen saturation levels at night to help you better understand your sleep quality. The new advanced sleep monitor estimates light, deep and REM stages of sleep, along with movement throughout the night. You can then review your sleep stats in the Garmin Connect Mobile app.
Another new feature: A Body Battery energy monitor that estimates your body's energy reserves, letting you know the optimal time for activity and rest.
"Using a combination of data gathered from stress, heart-rate variability, sleep and activity, a higher Body Battery indicates the time is optimal to be active whereas a lower number suggests rest is in order," Garmin says. "Body Battery assists users in making sense of patterns, demonstrating how behaviors and activities of the past few days influence how one feels at a given moment."
I've been playing around with an early review sample for 36 hours and I like how slim it is. I reviewed the earlier Vivosmart 3 and this model is even slimmer than that. Its monochrome touchscreen is easier to read -- it's a little brighter and crisper -- and I found it more responsive to my swipes and presses.
While slim activity trackers that pack in a ton of features aren't usually all that easy to navigate, I thought the Vivosmart 4 was more user-friendly than the Vivosmart 3.
Like the Vivosmart 3, this new model delivers excellent battery life -- up to seven days between charges -- and aside from the lightweight slim design, that strong battery life is one of the reasons to consider this type of activity tracker as your go-to wearable. It's also worth noting that like smartwatches it receives notifications from your phone (with vibration alerts), offers basic weather reports and can be used as a remote to control music playback on your phone. Android users can even reply to texts with preset messages.
I also like Garmin's Vivosport, which you can sometimes find for less than $150 and even less than that if you pick up a refurbished model. That model has GPS, while this doesn't.
The Vivosmart 3 costs $20 less than Fitbit's upcoming Charge 3 and as soon as we get a review sample of that activity tracker, I'll be able to compare the two models and perhaps tell you which one is better.