Muscle contractile and metabolic dysfunction is a common feature of sarcopenia of aging and chronic diseases: from sarcopenic obesity to cachexia.
Skeletal muscle is the most abundant body tissue accounting for many physiological functions. However, muscle mass and functions are not routinely assessed. Sarcopenia is defined as skeletal muscle loss and dysfunction in aging and chronic diseases. Inactivity, inflammation, age-related factors, anorexia and unbalanced nutrition affect changes in skeletal muscle. Mechanisms are difficult to distinguish in individual subjects due to the multifactorial character of the condition. Sarcopenia includes both muscle loss and dysfunction which induce contractile impairment and metabolic and endocrine abnormalities, affecting whole-body metabolism and immune/inflammatory response. There are different metabolic trajectories for muscle loss versus fat changes in aging and chronic diseases. Appetite regulation and physical activity affect energy balance and changes in body fat mass. Appetite regulation by inflammatory mediators is poorly understood. In some patients, inflammation induces anorexia and fat loss in combination with sarcopenia. In others, appetite is maintained, despite activation of systemic inflammation, leading to sarcopenia with normal or increased BMI. Inactivity contributes to sarcopenia and increased fat tissue in aging and diseases. At the end of the metabolic trajectories, cachexia and sarcopenic obesity are paradigms of the two patient categories. Pre-cachexia and cachexia are observed in patients with cancer, chronic heart failure or liver cirrhosis. Sarcopenic obesity and sarcopenia with normal/increased BMI are observed in rheumatoid arthritis, breast cancer patients with adjuvant chemotherapy and in most of patients with COPD or chronic kidney disease. In these conditions, sarcopenia is a powerful prognostic factor for morbidity and mortality, independent of BMI.
Department of Medical, Surgical and Health Sciences, Clinica Medica, AOUTS, University of Trieste, Italy.
Gianni
G
Biolo
Clinical Nutrition and Metabolism, Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden.
Tommy
T
Cederholm
Department of Clinical Medicine, Sapienza - University of Rome, Italy. Electronic address: maurizio.muscaritoli@uniroma1.it.
Maurizio
M
Muscaritoli
D000273:Adipose Tissue / Q000378:metabolism; D000368:Aged; D000375:Aging / Q000502:physiology*; D001823:Body Composition; D015992:Body Mass Index; D002100:Cachexia / Q000503:physiopathology*; D002908:Chronic Disease; D004734:Energy Metabolism; D005260:Female; D005973:Glutamine / Q000378:metabolism; D006801:Humans; D008297:Male; D044342:Malnutrition / Q000453:epidemiology / Q000473:pathology; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000473:pathology; D009752:Nutritional Status; D009765:Obesity / Q000503:physiopathology*; D015995:Prevalence; D055948:Sarcopenia / Q000175:diagnosis / Q000473:pathology*
D005973:Glutamine
Cachexia; Muscle contractile dysfunction; Muscle metabolic dysfunction; Pre-cachexia; Sarcopenia; Sarcopenic obesity