Abstract: With age, skeletal muscle loses mass, strength, and metabolic function, partly due to oxidative stress and impaired mitochondrial responses, contributing to frailty and sarcopenia. This project develops novel three-dimensional engineered muscle tissue (3D-EMT) from primary human myoblasts of older (>70 years) and younger (36–69 years) adults in the SOMMA studies, using CD56-sorted cells cast into fibrin/Matrigel hydrogels and assessed with the Mantarray system for force, fatigue, and contraction/relaxation kinetics. Preliminary results show bimodal distributions in muscle function and metabolism, suggesting aged phenotypes are retained in vitro, with future applications in drug testing and intervention studies for aging skeletal muscle.