Impaired muscle function with aging. A background factor in the incidence of fractures of the proximal end of the femur.

Muscle biopsy material from vastus lateralis musculus quadriceps was obtained during surgery from 43 66-100-year-old female and nine 70-89-year-old male patients with fresh hip fractures. Before the accident, 18 women and two men were clinically healthy, and in the others, one-third had cardiovascular, one-third locomotor, and one-third neurologic disorders. Twelve women lived in institutions. The other women and all of the men lived in their own homes. A striking finding was a more advanced reduction in muscle fiber size in the vastus lateralis, especially in the fast twitch (FT) fibers. The reduction occurred in preaccident clinically healthy fracture patients. With advancing age, the proportions of the slow twitch (ST) and FT fibers remained the same. Well-maintained, enzymatic metabolic capacity, moderate neuropathic changes, and absence of myopathic changes indicate that the quality of the muscle tissue is relatively well preserved, even in elderly patients with hip fractures. Muscle fiber atrophy and weakness in muscle strength may be attributable in part to a low physical activity and are possibly reversible with exercise in some individuals.