Biomarkers for Physical Frailty and Sarcopenia: A “Two-Body Problem”

This chapter presents multi-marker biomarker discovery as an approach for capturing the complexity of physical frailty and sarcopenia (PFandS), overviews candidate biomarkers for PFandS, and discusses relevant pathways involving these mediators. PFandS has a multifactorial etiology that recapitulates all biological hallmarks of aging. Multi-marker analysis has increasingly been recognized as a complementary and more sophisticated strategy for investigating highly dynamic and complex conditions, including PFandS. The development of biological markers that can be measured in biofluids at any time point and be used in a cost-effective manner to guide the diagnosis and facilitate the monitoring of PFandS are highly sought after. The assessment of clinical, functional, and imaging parameters was used for identifying PFandS. Although paving the way for biomarker discovery, all the reported studies have the caveat of investigating single domains of the PFandS condition.