Being in physical activity (PA) lowers the risk of cardiovascular disease, cancer, and premature death. Despite these well-known benefits, many people do not meet the recommended PA levels and are unsure whether they have done enough for their health. Common measures focus on steps per day or total minutes and do not capture how hard the work is. Intensity of PA appears to carry independent value for health beyond steps and minutes alone. Accurate quantification of PA is therefore critical for understanding its relationship with long-term health outcomes. Yet, most consumer wearables rely on algorithms with no validation against clinical or mortality outcomes. Our project aims to fill this gap by validating and extending the concept of the Activity Quotient (AQ). The AQ is an empirically derived metric score from 0 to 100 that quantifies the health equivalence measured by wearables of how hard and how long a person is active. By incorporating fitness level, health status, and age-related risk estimates, AQ allows for a nuanced picture of the health effects from PA. Unlike current step- or MET-based algorithms, AQ is designed to reflect physiological and epidemiological evidence to answer a practical question: have you done enough PA for health this week?
This project aims to test whether a simple weekly, weighted metric score (AQ) predicts clinical and mortality outcomes more accurately than traditional PA measures. Specifically, we will connect and validate AQ to key endpoints such as all-cause and cause-specific mortality, major cardiovascular events, type 2 diabetes, and cancer. Further, we aim to calibrate equivalence across light, moderate, and vigorous intensities, and translate findings into scalable algorithms for wearable devices and health monitoring. By providing a weekly number that reflects both intensity and duration, AQ could help people, clinicians, and public health services to translate PA into a simple green-light signal for health.