The crashing wave of activity tracking “wearables” opens up a tremendous opportunity to unveil previously hidden but pivotal signatures of disability and disease. To achieve this promise, the understanding, interpretation and analysis of complex multimodal data produced by such devices becomes crucial. This roundtable will provide an overview of the instruments that are available for real-time measurement of physical activity as well as a guidance on the strengths and limitations of current methods for measuring physical activity A major part of the roundtable will be devoted to reviewing methods on how to best analyze and interpret these data to utilize the unprecedented temporal resolution that subsequently could lead to new biomarkers for interventions. The roundtable discussion will be convened to actively involve participants and to share experience and expertise.