A look at the accuracy of commercial fitness trackers, as studies show factors like having darker skin or shuffling when walking can throw off sensors (Sara Harrison/The Markup)

Sara Harrison / The Markup:
A look at the accuracy of commercial fitness trackers, as studies show factors like having darker skin or shuffling when walking can throw off sensors  —  In a 2019 study, 18 senior citizens took a stroll on some treadmills while armed to the hilt with fitness trackers.