Development of a proposed guide to identify, screen and appraise self-report and device-based measures of habitual physical activity in systematic reviews: a methodological protocol.

Habitual physical activity (PA) is a fundamental determinant of health, yet its assessment and reporting vary substantially across research studies, creating persistent challenges for evidence synthesis. Systematic reviews that aim to synthesise habitual PA outcomes are frequently hindered by heterogeneity in measurement tools, implementation protocols, outcome metrics, and reporting practices. These heterogeneities complicate decision-making regarding study inclusion, data extraction, data analysis, reduce the reliability of meta-analysis, and limit transparency, comparability, and interpretability of systematic review findings. Drawing on insights from a recent systematic review, this commentary highlights key methodological challenges specific to assessment and reporting of habitual PA within systematic reviews. We argue that the absence of standardised criteria for identifying, screening, and appraising habitual PA measures is a major contributor to these challenges, and undermines transparency, comparability, and interpretability of systematic review findings. To address this gap, we present a protocol for a structured screening guide, describe its conceptual domains, and discuss the need for empirical validation. We call for a collaborative, consensus-driven process to test its reliability, feasibility, and validity before wider adoption. Establishing agreed methodological guidance is essential to strengthen the quality, credibility, and policy relevance of systematic reviews of habitual PA.