To the Editor Advances in physical activity monitoring provide clinicians and researchers with opportunities to further understanding of the health benefits of physical activity, yet the proliferation of wearable device technology has created a black box in terms of accuracy and reliability. Manufacturers create proprietary algorithms to estimate steps, distance, and energy expenditure from measured acceleration, making it impossible to compare raw acceleration data between devices. Moreover, these algorithms are created using younger, healthier populations,1 making their validity in older, sicker individuals unclear.
Schrack J, Zipunnikov V, Crainiceanu C. Electronic Devices and Applications to Track Physical Activity. JAMA. 2015;313(20):2079-2080. doi:10.1001/jama.2015.3877