Accelerometer data processing pipeline using ActiLife software for reproducible 24-hour physical behavior assessment in the ELSA-Brasil cohort

This protocol describes a standardized and reproducible accelerometer data collection and processing workflow implemented in the ELSA-Brasil cohort using ActiLife software. The protocol enables consistent derivation of physical activity, sedentary behavior, and sleep metrics from hip-worn accelerometers in large epidemiological studies. Protocol summary: • Defines standardized procedures for accelerometer configuration, deployment, and data acquisition under 24-hour free-living conditions; • Specifies predefined ActiLife processing parameters including wear-time validation, sleep detection, and activity intensity classification; • Generates harmonized accelerometry-derived variables supporting replicable epidemiological analyses and cross-cohort comparability; This protocol provides a parameter-explicit framework for accelerometer data processing using ActiLife software and may serve as a reference standard for cohort studies using similar accelerometry approaches.