How to choose a fitness tracker

If you want more advanced fitness insights, three metrics you should:

• HRV is a metric measuring the fluctuations of time between heartbeats. It’s often used as a measure of how well you’ve recovered from a workout or to estimate stress levels.
• SpO2 is often used interchangeably with pulse oximetry. The gist is that it measures how oxygenated your blood is. Companies are still figuring out how to best utilize this metric, but you frequently see it pop up in sleep and recovery tracking.
• VO2 Max is a metric that measures the maximum amount of oxygen your body can use during intense exercise.

If you’re looking to leave your phone at home, you might be better off with a smartwatch that has decent health features.

The thing about fitness trackers is they’re often lacking on the connectivity front. You’re likely not going to find them including LTE, robust third-party apps, contactless payments, or a digital assistant. Or if you do, it might be one or two of those — but certainly not all of them.

• When browsing your options, don’t forget to check the size and thickness of the watch, as well as the materials it’s made from. If your fitness tracker isn’t comfortable, you’re not going to wear it.
• Comfort is especially important if sleep tracking is a priority. You don’t want to buy a big hulking tracker. If you have trouble sleeping with wrist-based trackers, so you might also want to look into non-wrist-based sleep gadgets.
• A bad fit can also warp your data. If a tracker isn’t snug against your skin during exercise, you might get inaccurate heart rate readings.