How accurate are the activity monitoring devices Fitbit, Polar etc in measuring parameters like number of steps, calories burnt, distance, standing, walking, jog run etc.?

WHOOP determines your Sleep Performance by measuring the total amount of sleep you got as a function of the sleep it determined you needed. This Sleep Performance is one factor used to determine your level of recovery for the next day. This allows you to better plan your training and day’s workout, rather than complying…