Comparative Accuracy of a Wrist-Worn Activity Tracker and a Smart Shirt for Physical Activity Assessment

The purpose of the current study was to determine the accuracy of the Fitbit Charge HR and Hexoskin smart shirt. Participants (n = 32, age: 23.5 +/- 1.3 years) wore a Fitbit and Hexoskin while performing 14 activities in a laboratory and on a track (lying, sitting, standing, walking various speeds and inclines, jogging, and cycling). Steps, kcals, heart rate, breathing rate, depth, and volume were measured by the Fitbit and Hexoskin and compared to criterion measures. The Fitbit and Hexoskin had low mean absolute percent error for steps (9.7%, 9.4%). The mean absolute percent error was low for heart rate (6.6% and 2.4%), with the Fitbit underestimating heart rate at higher intensities. Both devices had high mean absolute percent error for kcals (43.7% and 27.9%, respectively), and the Hexoskin had high mean absolute percent error for breathing rate, depth, and volume (19.4%, 35.6%, and 33.6%, respectively). The Fitbit and Hexoskin have utility for measurement of some, but not all, physical activity and physiologic variables which they measure.