I have two watches on my left wrist, another on my right arm, a ring on my finger and a sensor embedded in my bra. No one should ever wear this many fitness trackers simultaneously. But in this moment, I am letting the latest heart-rate-sensing, sleep-capturing, workout-recording wearables from Apple, Fitbit, Garmin, GRMN,Whoop and Oura capture all my data, to see which ones do the best job.

Whether you are training for a race or trying to lose the Quarantine 15, a fitness tracker can provide a helpful motivational nudge. But choosing the right one depends on your preferred activities and health goals—and requires an understanding of what data is most useful to you.

New trackers are much more than pedometers and heart-rate monitors. They also measure blood-oxygen levels, a sign of overall health and altitude acclimation. And they capture heart-rate variability, the difference in time between each heartbeat, which can provide feedback about your body’s ability to recover from exercise. But how accurate are the metrics? Read the full article here