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.

翻译：身体活动不足是全球第四大死亡风险因素。因此，了解青少年的身体活动模式对于管理和减轻非传染性疾病至关重要。由于利用公民自有智能手机以合乎伦理的方式获取身体活动大数据的数字公民科学方法可以变革身体活动监测，本研究旨在比较使用智能手机部署的回顾性验证调查与前瞻性时间触发的移动生态瞬时评估所报告的青少年身体活动频率。采用数字公民科学方法，本研究于2018年（8月31日至12月31日）在加拿大萨斯喀彻温省招募了青少年公民科学家（N=808）。青少年公民科学家（13至21岁）在八天内通过前瞻性移动生态瞬时评估和回顾性调查报告了他们的身体活动。在回顾性与通过移动生态瞬时评估的前瞻性报告身体活动频率方面发现了显著差异（p<0.000）。种族、父母教育水平和力量训练与前瞻性身体活动频率相关；然而，与回顾性身体活动频率均无显著关联。随着全球数字设备的普及以及青少年尤其具备较高的数字素养，利用移动生态瞬时评估进行合乎伦理的身体活动监测的数字公民科学为管理和预防青少年非传染性疾病提供了一种有前景的方法。