What does your resting heart rate, SpO2, REM sleep, etc. really show?

What does your resting heart rate, SpO2, REM sleep, etc. really show?

Fitness trackers, pedometer apps, heart rate monitors, etc. have lead to the ‘quantified self’. Our physical health is measured by means of number of steps taken, resting pulse, or VO2max values. But what do these values actually mean and how relevant are they for health? Here’s an overview.