Passive force and viscoelastic properties of single fibers in human aging muscles

Changes in stiffness or extensibility of the muscle or muscle–tendon unit with aging could lead to impaired function and an increased vulnerability to injury. We aimed to investigate the passive force and viscoelastic properties of single muscle fibers in older adults. Seven older adults (mean age 79.0 ± 3.8 years) and 10 young control (mean age 25.6 ± 4.5 years) were recruited. Biopsy specimens were obtained percutaneously from m. vastus...