Digital citizen science for ethical surveillance of physical activity among youth: mobile ecological momentary assessments vs. retrospective recall

Physical inactivity is the fourth leading risk factor of mortality globally. Hence, understanding the physical activity (PA) patterns of youth is essential to manage and mitigate non-communicable diseases. As digital citizen science approaches utilizing citizen-owned smartphones to ethically obtain PA big data can transform PA surveillance, this study aims to understand the frequency of PA reported by youth using smartphone-deployed retrospective validated surveys compared to prospective time-triggered mobile ecological momentary assessments (mEMAs). Using a digital citizen science methodology, this study recruited youth citizen scientists (N = 808) in 2018 (August 31- December 31) in Saskatchewan, Canada. Youth citizen scientists (age 13 to 21) reported their PA using prospective mEMAs and retrospective surveys over an eight-day period. A significant difference was found in reporting the frequency of PA retrospectively vs. prospectively via mEMAs (p < 0.000). Ethnicity, parental education, and strength training were associated with prospective PA frequency; however, no associations were significant with retrospective PA frequency. With access to ubiquitous digital devices growing worldwide, and youth having particularly high digital literacy, digital citizen science for the ethical surveillance of PA using mEMAs presents a promising approach for the management and prevention of non-communicable diseases among youth.