Читать книгу Pathy's Principles and Practice of Geriatric Medicine - Группа авторов - Страница 187

In contrast to changes in fat and bone, an increase in muscle mass is achievable to a significant degree only with progressive resistance training or generalised weight gain from extra energy and protein consumption. Accretion of lean tissue with exercise has a potential role in preventing diabetes,⁸² functional dependency, falls, and fractures, and is important in the treatment of chronic diseases and disabilities, which are accompanied by disuse, catabolism, and sarcopenia. For some diseases, such as type 2 diabetes mellitus, there are potential advantages to both minimising fat tissue and maximising muscle tissue since these compartments have opposite and likely independent effects on insulin resistance in older adults. Resistance exercise coupled with a leucine‐enriched essential amino acid supplement (when diet is inadequate) is recommended to treat sarcopenia.⁸³ Muscle wasting or atrophy from any cause will exacerbate problems related to the extent and rate of the peripheral disposal of glucose into skeletal muscle, which is essential for maintaining euglycaemia in response to normal metabolism, meals, or other stressors. There is evidence from a variety of epidemiological and experimental studies that muscle weakness, decreased muscle mass, decreased activation of glycogen synthase, and alterations in numbers of type IIb skeletal muscle fibres are related to, and may precede, insulin resistance, glucose intolerance, and type 2 diabetes expression. Thus, the typical alterations in body composition with ageing (decreased muscle mass and increased visceral adiposity) are potentially independently related to the development of impaired glucose homeostasis in older adults.