Validation of steps countering recorded with a smartwatch

Activity trackers are becoming increasingly popular in everyday life, sport and research. Accurate measurement of step counts is essential for understanding an individual's daily activity levels and promoting healthier lifestyles. As the sensor technology has become very sophisticated, such a device can be worn on the body for several hours or days without restricting the subject's daily activities. The aim of this study was to evaluate the accuracy of a commercially available wrist-worn pedometer in accurately recording step counts.

A total of twenty-one subjects participated in this comparative study by running at various speeds in a laboratory setting while wearing a Garmin Forerunner 245 Music watch (Garmin Ltd, Schaffhausen, Switzerland) on each wrist. Simultaneously, their steps were recorded by a camera system. The step counts recorded by the pedometer were compared with the counts obtained by the camera system. Descriptive statistical analyses such as Pearson correlation and Bland-Altman plots were used to assess the accuracy and reliability of the pedometer.

For most settings the results on the treadmills showed a high correlation between the pedometer and the camera system. On the step machine the results showed a low correlation between the pedometer and the camera system, the pedometer showed a systematic bias by consistently overestimating the number of steps. Bland-Altman plots showed that the results were within the limits of agreement.

Although pedometers provide a convenient tool for monitoring step count, this study highlights some limitations and potential inaccuracies of a commercially available pedometer. Our study indicates that the Garmin watch is sufficiently accurate to be used as a measurement tool in a treadmill running environment.