Humaine, Clermont‐Ferrand, France INRA, UMR 1019, Unite de Nutrition Humaine, CRNH, Clermont‐Ferrand, France
Jean Woo Department of Medicine & Therapeutics, Chinese University of Hong Kong, Hong Kong, China
Solomon Yu National Health and Medical Research Council Centre of Research Excellence in Frailty and Healthy Ageing, University of Adelaide, Adelaide, South Australia, Australia
Yves Rolland INSERM Unit 1027; Université de Toulouse; Gérontopole, Centre Hospitalier Universitaire de Toulouse, Toulouse, France
Mauro Zamboni Department of Medicine, Geriatric Division, University of Verona, Verona, Italy
Marta Zampino Intramural Research Program, National Institute on Aging, Baltimore, MD, USA
Jesse Zanker Department of Medicine‐Western Health, Melbourne Medical School, University of Melbourne, St Albans, Melbourne, VIC, Australia Australian Institute for Musculoskeletal Science (AIMSS), University of Melbourne and Western Health, St Albans, Melbourne, VIC, Australia
Preface
Since the original coining of the term sarcopenia in 1988, there has been a rapid increase in the development of scientific approaches to its pathophysiology, definition (together with ethnic appropriate cut‐offs), and management. This was highlighted when sarcopenia was established as a muscle disease with its own ICD‐CM diagnosis code (ICD‐10‐CMM62.84). Primary sarcopenia (age related) is of central interest to geriatricians, nutritionists, gerontologists, epidemiologists, biologists, physical and occupational therapists, and all health professionals who provide care for older persons. Secondary sarcopenia has become an increasingly important, treatable side effect of chronic diseases, e.g. congestive heart failure or chronic obstructive pulmonary disease, in many persons.
Since the first edition of Sarcopenia some eight years ago, there have been major advances in the understanding of the basic science concepts of how aging interacts with muscles to alter its function. This has been coupled with an increased knowledge in methodology to measure muscle mass and function. There has been a realization that the decline in function due to muscle loss is the hallmark in the development of sarcopenia. This has led to more sophisticated definitions of the disease and a recognition that these definitions require ethnic‐specific definitions. While the primary treatment of sarcopenia relies on resistance and other exercises together with nutritional approaches, a large number of pharmacological agents to treat sarcopenia are under development. These exciting and rapid changes have led us to produce a second edition of this book.
This new edition remains a clear and precise reference work for all those health professionals, exercise physiologists, and researchers interested in understanding the complexity of sarcopenia. This book provides the state of art of the complexity involved in the biological aspects of age‐related muscle wasting alongside the direct effects of disease on muscles. It explores the rapidly increasing epidemiological knowledge demonstrating the devastating effects of sarcopenia on health outcomes and quality of life of individuals. It explores in detail the modern diagnostic and management approaches to recognizing and improving outcomes in individuals with sarcopenia. To do this we have assembled a wide range of authors from around the world, who are experts in this topic area. We also focus on primary and secondary prevention of sarcopenia as important approaches to enhance the quality of life in older persons.
This book represents a state‐of‐the‐art textbook, with a comprehensive approach to sarcopenia. We hope it will be a valuable reference tool to all those who are interested in this topic. Our authors have taken complex topics and written about them in a clear way allowing access to the knowledge for those starting out in the field, as well as expert researchers and clinicians who are interested in recognizing and treating sarcopenia.
Alfonso J. Cruz‐Jentoft and John E. Morley
CHAPTER 1 Definitions of Sarcopenia
Alfonso J. Cruz‐Jentoft1, Beatriz Montero‐Errasquín2, and John E. Morley3
1 Servicio de Geriatría, Hospital Universitario Ramón y Cajal (IRYCIS), Universidad Europea de Madrid, Madrid, Spain
2 Servicio de Geriatría, Hospital Universitario Ramón y Cajal (IRYCIS), Madrid, Spain
3 Division of Geriatric Medicine, Saint Louis University School of Medicine, St. Louis, MO, USA
SARCOPENIA: BIRTH AND FIRST STEPS
Irving Rosenberg is credited to have coined the term sarcopenia (from the Greek roots – sarx = flesh and ‐penia = low, meaning “poverty of flesh”) in 1988 to describe the striking age‐related decline in lean body mass and its potential functional significance [1].
Methods to estimate muscle mass (or lean body mass) were increasingly available, as were epidemiological studies using such techniques. Based on these parameters, sarcopenia was operationally defined as a gradual loss of muscle mass. For instance, Baumgartner used a definition based on appendicular skeletal muscle mass estimated by dual‐energy x‐ray absorptiometry (DXA), corrected for height, and defined sarcopenia as being two standard deviations below sex‐specific means of healthy young persons (18–40 years) of a reference population [2]. Longitudinal studies confirmed that a progressive reduction in muscle mass was present in both males and females [3]. Muscle mass declines at approximately 1–2% per year after the age of 50 years. Sarcopenia, when defined as a severe muscle mass loss (two standard deviations below healthy young populations), is present in 5–13% of persons of 60–70 years old and 11–50% of those over 80 years [4].
While the definition of sarcopenia based on a reduced muscle mass alone served the scientific community fairly well, it was less satisfying for clinicians, the pharmaceutical industry, and regulatory agencies. Unlike bone mineral density, measures of muscle mass have not been widely adopted by clinicians. Regulatory agencies have failed to accept that restoration of muscle mass is a valid reason to allow a drug to be approved for use. Also, many crucial aspects of sarcopenia are missed by the simplistic use of muscle mass as a measure, which has shown to be a weak predictor of outcomes; and the link between muscle mass, muscle function (defined by muscle strength and power), physical performance, and other downstream outcomes is not linear [5–8]. The fact that all clinical measures of muscle mass are in fact estimations and have a wide range of measurement error may partially explain this situation [9]. Research has also showed that loss of muscle strength is two to five times faster than loss of muscle mass and is associated with changes in muscle quality (defined as intramuscular fat) and is more predictive of outcomes [3, 8].
GROWTH AND ADOLESCENCE OF SARCOPENIA
In the first decade of the twenty‐first century, the relevance of muscle function was so clear that different lines of action were proposed, including the use of different terms to name the condition. Dynapenia and kratopenia were suggested as alternative terms to describe the loss of muscle strength and power [8, 10], and myopenia as an alternative for universal skeletal muscle wasting [11]. However, six different international consensus definitions published at the end of the decade all proposed redefining sarcopenia by adding the loss of muscle mass to the loss of muscle function, with slightly different approaches [10, 12–16].
European Working
