Aim: It is important to assess not only the total skeletal muscle mass, but also the intracellular and extracellular compartments of skeletal muscle to examine the actual relationship between skeletal muscle mass and physical functions. Segmental bioelectrical impedance spectroscopy is a unique tool with which to assess intracellular and extracellular water in the limbs. The aim of the present study was to examine the application of segmental bioelectrical impedance spectroscopy to the assessment of skeletal muscle mass in the elderly.
Methods: A total of 73 healthy elderly men and 20 elderly men requiring care and using an ambulatory day-care service of the public long-term care insurance system participated in the present study. The intracellular and extracellular water in the upper and lower legs were assessed by segmental bioelectrical impedance spectroscopy. The gait speed, grip strength and maximal isometric knee extension strength were measured.
Results: The elderly requiring care had significantly lower intracellular water than did healthy elderly in the upper and lower legs. A significant relative expansion of extracellular water against total water was observed in the elderly requiring care. Receiver operating characteristic curves showed that the area under the curve for the intracellular water index was similar to that for muscle strength in the discrimination of elderly requiring care.
Conclusions: The elderly requiring care had a relative expansion of extracellular water in the legs, which could have masked actual muscle atrophy. Segmental bioelectrical impedance spectroscopy would be useful for the assessment of skeletal muscle cell mass and sarcopenia in the elderly.
Keywords: bioelectrical impedance spectroscopy; extracellular fluid water; frail elderly; intracellular fluid water; muscle strength; skeletal muscle mass.
© 2014 Japan Geriatrics Society.