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## **Meet the editor**

Craig S. Atwood, PhD is an Associate Professor of Medicine at the University of Wisconsin and a Health Science Specialist with the Geriatric Research, Education and Clinical Center at the William S. Middleton Memorial Veterans Administration Hospital in Madison. Dr. Atwood completed his PhD in Biochemistry at the University of Western Australia in Perth, Australia prior

to post-doctoral fellowships at the National Cancer Institute, NIH, Bethesda, and Massachusetts General Hospital, Boston. He has held faculty positions at Harvard Medical School and Case Western Reserve University prior to his current position where he directs the research program of the Laboratory for Endocrinology, Aging and Disease. Dr. Atwood has broad research interests related to the endocrinology of aging as elaborated upon in 'The Reproductive-Cell Cycle Theory of Aging'. He has published over 200 scientific articles, has served on numerous review boards and is an Editor of more than 20 scientific journals including the Journal of Biological Chemistry. In 2006 he received the Zenith Fellows Award from the Alzheimer's Association in recognition of his research.

Contents

**Preface IX** 

**Part 1 Functional Loss Associated with Aging 1** 

Chapter 3 **The Epidemiology of Vascular Dementia 41**  Demet Ozbabalık, Didem Arslantaş

Chapter 4 **Swallowing Difficulties in Elderly People:** 

Marie-Hélène Lacoste-Ferré,

**Impact of Maxillomandibular Wedging 51** 

**Mortality with Fitness Measurements and** 

**Nonparticipation in an 80-Year-Old Population 59**  Yutaka Takata, Toshihiro Ansai, Inho Soh, Shuji Awano, Yutaka Yoshitake,Yasuo Kimura, Ikuo Nakamichi, Sumio Akifusa, Kenichi Goto, Akihiro Yoshida, Ritsuko Fujisawa, Kazuo Sonoki, and Tatsuji Nishihara

**Neuromuscular Functions of Human Movements 105** 

Sophie Hermabessière and Yves Rolland

**Part 2 Preventative Strategies for Maintenance of Health and Extending Longevity 83**

Chapter 6 **Behavioral Treatment for Geriatric Syndrome 85** 

Noran N. Hairi, Awang Bulgiba, Tee Guat Hiong and Izzuna Mudla

Chapter 1 **Physical Function in Older People 3**  Noran N. Hairi, Tee Guat Hiong, Awang Bulgiba and Izzuna Mudla

Chapter 2 **Sarcopenia in Older People 29** 

and Nese Tuncer Elmacı

Chapter 5 **Association of Disease-Specific** 

Hunkyung Kim

Chapter 7 **Aging and Exercise Training on the** 

Junichiro Yamauchi

### Contents

#### **Preface XI**

	- **Part 2 Preventative Strategies for Maintenance of Health and Extending Longevity 83**

X Contents


	- **Part 3 End of Life Care 177**

### Preface

The decline in physical and mental functionality with aging has been attributed to the endocrine dyscrasia, associated with the loss of the reproductive function with aging (Bowen and Atwood, 2004; 2011). These biomolecular changes result in the dysfunction and/or death of cells, and ultimately the loss of tissue function, that presents clinically as conditions of aging (e.g. osteoporosis, arthritis) or as disease (e.g. coronary heart disease, dementia). This book addresses a broad range of issues related to geriatrics, including: 1) characterizing functional loss in the geriatric patient 2) preventive strategies for the maintenance of health in the geriatric population, and 3) end of life issues for geriatric patients that range from legal issues to patient education.

The first section of this book – 'Functional Loss Associated with Aging' addresses the physical and mental decline in function associated with aging. The first chapter by Hairi et al addresses the age-related changes in physical functioning from the perspective of demographics, interventions and the further research required to guide public health practitioners and clinicians as to the most appropriate interventions to improve and maximize a person's function. Hairi et al follow up this first chapter with an examination of sarcopenia as a major cause of the decline in physical function with age. As noted by the author, current research has shown promising results in the assessment of sarcopenia, although further work is required in the management of sarcopenic patients, in terms of prevention as well as treatment. The next two chapters focus on specific changes in functional decline in the elderly, namely the cognitive decline associated with vascular dementia (Ozbabalik et al.) and swallowing difficulties (Lacoste-Ferre). Ozbabalik examine the epidemiology of vascular dementia including the risk factors for the development of this form of dementia. Lacoste-Ferre present new data, suggesting that disrupted mastication appears to be a factor favoring dysphagia in the elderly, and that the preservation of dental status is a good objective to prevent dysphagia in the institutionalized frail and dependent elderly. Finally, Takata et al report on how lower fitness levels, for various muscle strength tests is associated with increases in all-cause mortality as well as diseasespecific mortality in an 80-year-old community-dwelling population. This data fits well with previous literature indicating a lower level of physical activity, physical fitness, or muscle strength is associated with a higher total mortality in an elderly population.

In the next section of the book - 'Preventative Strategies for Maintenance of Health and Extending Longevity' we move from an appreciation of functional decline in the elderly to strategies of preventing frailty and extend longevity. In the first chapter of this section, Hunkyung reviews risk factors for geriatric syndrome prior to elaborating on treatments for frailty and falls prevention involving nutrition and exercise strategies. Yamauchi follows by also reviewing the importance of exercise (resistance training) as a countermeasure against sarcopenia and loss of muscle function. Indeed, resistance training at home or in a community center (without the need for strength training equipment) allows for important improvements in muscle function for the elderly. In a similar vein, in the next chapter Yamada et al highlight the importance of tailoring fall prevention programs to the elderly adult's level of physical well-being. Kojimahara advocate the benefits of annual immunization with influenza vaccine and 23-valent pneumococcal polysaccharide vaccine (PPV23) in the elderly with and without chronic obstructive pulmonary disease. Decreasing the risk of heart disease, the major killer in western society, by attenuating post-prandial hyperglycemia is the topic of the next chapter by Mori et al. In this paper, intestinal glucose absorption after fermented milk ingestion was shown to be attenuated experimentally in mice as well as clinically in humans. Thus, the use of 'Caspian Sea Yogurt' such as used by longliving populations in Georgia is suggested to reduce cardiovascular risk and to contribute to the longevity. The final chapter in this section by Kececi and Bulduk examines healthcare personnel attitudes towards the ability of the elderly to understand and learn new information. The authors discuss the need for healthcare professionals to be more in tune with the elderly, and to understand the physical, psychological and socio-cultural changes that might impact learning in the elderly in order to develop more efficient strategies to improve health promotion and wellness.

Preface XI

**Craig S. Atwood** 

USA,

Joondalup, Australia

Geriatric Research, Education and Clinical Center,

School of Exercise, Biomedical and Health Sciences

Veterans Administration Hospital,

University of Wisconsin,Madison,

Department of Medicine,

Edith Cowan University

and longevity, and finally the complex issues surrounding the end of life care of the

Bowen, R.L. and Atwood, C.S. (2004). Living and Dying for Sex: A theory of aging

Atwood C.S. and Bowen R.L. (2011). The reproductive-cell cycle theory of aging: An

update. Experimental Gerontology, 46(2-3), 100-107.

based on the modulation of cell cycle signaling by reproductive hormones.

patient.

**References** 

Gerontology, 50(5), 265-290.

The final section of the book examines end of life care. The first chapter by Kahana et al advocate for educational interventions to help older patients marshal responsive care during the extended period of service needs during the final years. As indicated by the authors, effective advocacy by patients and families is an important determinant upon making the final period of life more comfortable and livable. Schelp addresses the attitudes toward autonomy and legal instruments at the end of life, and discusses the multidimensional nature of the medical, social, cultural, religious, and economic aspects involved in end of life decision making and care. The final chapter by Ratcliffe et al discusses the challenges and opportunities of health economics with respect of geriatric care. These authors discuss the methods for assessing the cost effectiveness of new health care technologies and models of aged care service delivery, as well as the methods adopted by health economists for measuring and valuing patient or consumer preferences in health care.

It is hoped that the papers and reviews described here will help to update the geriatrics research and clinical community on recent advances in identifying and quantitating functional loss experienced by the elderly, strategies to maintain function and longevity, and finally the complex issues surrounding the end of life care of the patient.

> **Craig S. Atwood**  Geriatric Research, Education and Clinical Center, Veterans Administration Hospital, Department of Medicine, University of Wisconsin,Madison, USA, School of Exercise, Biomedical and Health Sciences Edith Cowan University Joondalup, Australia

#### **References**

X Preface

wellness.

patient or consumer preferences in health care.

In the next section of the book - 'Preventative Strategies for Maintenance of Health and Extending Longevity' we move from an appreciation of functional decline in the elderly to strategies of preventing frailty and extend longevity. In the first chapter of this section, Hunkyung reviews risk factors for geriatric syndrome prior to elaborating on treatments for frailty and falls prevention involving nutrition and exercise strategies. Yamauchi follows by also reviewing the importance of exercise (resistance training) as a countermeasure against sarcopenia and loss of muscle function. Indeed, resistance training at home or in a community center (without the need for strength training equipment) allows for important improvements in muscle function for the elderly. In a similar vein, in the next chapter Yamada et al highlight the importance of tailoring fall prevention programs to the elderly adult's level of physical well-being. Kojimahara advocate the benefits of annual immunization with influenza vaccine and 23-valent pneumococcal polysaccharide vaccine (PPV23) in the elderly with and without chronic obstructive pulmonary disease. Decreasing the risk of heart disease, the major killer in western society, by attenuating post-prandial hyperglycemia is the topic of the next chapter by Mori et al. In this paper, intestinal glucose absorption after fermented milk ingestion was shown to be attenuated experimentally in mice as well as clinically in humans. Thus, the use of 'Caspian Sea Yogurt' such as used by longliving populations in Georgia is suggested to reduce cardiovascular risk and to contribute to the longevity. The final chapter in this section by Kececi and Bulduk examines healthcare personnel attitudes towards the ability of the elderly to understand and learn new information. The authors discuss the need for healthcare professionals to be more in tune with the elderly, and to understand the physical, psychological and socio-cultural changes that might impact learning in the elderly in order to develop more efficient strategies to improve health promotion and

The final section of the book examines end of life care. The first chapter by Kahana et al advocate for educational interventions to help older patients marshal responsive care during the extended period of service needs during the final years. As indicated by the authors, effective advocacy by patients and families is an important determinant upon making the final period of life more comfortable and livable. Schelp addresses the attitudes toward autonomy and legal instruments at the end of life, and discusses the multidimensional nature of the medical, social, cultural, religious, and economic aspects involved in end of life decision making and care. The final chapter by Ratcliffe et al discusses the challenges and opportunities of health economics with respect of geriatric care. These authors discuss the methods for assessing the cost effectiveness of new health care technologies and models of aged care service delivery, as well as the methods adopted by health economists for measuring and valuing

It is hoped that the papers and reviews described here will help to update the geriatrics research and clinical community on recent advances in identifying and quantitating functional loss experienced by the elderly, strategies to maintain function


**Part 1** 

**Functional Loss Associated with Aging** 

## **Part 1**

## **Functional Loss Associated with Aging**

**Physical Function in Older People** 

 *Faculty of Medicine, University of Malaya, Kuala Lumpur,* 

 *Faculty of Medicine, University of Malaya, Kuala Lumpur,* 

*2JCUM, Centre for Clinical Epidemiology and Evidence-Based Medicine,* 

*3Institute for Public Health, National Institutes of Health, Ministry of Health,* 

Aging is a natural process. Improved maternal and infant health, better survival in infancy, childhood and early adult life, has led to increase life expectancy of older people. As of 2008, 7% (506 million) of the world's population was aged 65 years and older, an increased of 10.4 million since 2007 (Kinsella K and Wan He 2009). The current pace of population aging varies widely. While developed countries have relatively high proportions of people aged 65 years and over, the most rapid increases in older people are in the developing world. As of 2008, 62% (313 million) of the world's population aged 65 and over lived in developing countries (Kinsella K and Wan He 2009). Many developing countries will be experiencing a sudden rise in the proportion of older people within a single generation, with far less well developed infrastructure. In contrast, most developed countries have had decades to adjust to the changing age structure and this change has been supported by relative economic

The implications of longer life mean increased risk of poor physical function as expounded by the theories of population health change. Four theories have been proposed in discussing

The expansion of Morbidity/Disability Theory (Gruenberg EM 1977), suggests that the gain in life expectancy in older people is mainly due to technological advances and secondary prevention strategies that have extended the life of older people with disability and underlying illness. This results in living with non-fatal diseases such as vision loss, arthritis, chronic pain and other diseases of old age, therefore living longer means living with more

The opposing theory is called the Compression of Morbidity/Disability Theory(Fries 1980; Fries 2005). He suggested that primary prevention strategies modify risk factors for

**1. Introduction** 

prosperity.

years of disability.

**2. Theories of population health change** 

the consequences of increased life expectancy in older people.

Noran N. Hairi1,2, Tee Guat Hiong3, Awang Bulgiba1,2 and Izzuna Mudla4 *1Department of Social and Preventive Medicine,* 

*4Ministry of Health,* 

*Malaysia* 

### **Physical Function in Older People**

Noran N. Hairi1,2, Tee Guat Hiong3,

 Awang Bulgiba1,2 and Izzuna Mudla4 *1Department of Social and Preventive Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, 2JCUM, Centre for Clinical Epidemiology and Evidence-Based Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, 3Institute for Public Health, National Institutes of Health, Ministry of Health, 4Ministry of Health, Malaysia* 

#### **1. Introduction**

Aging is a natural process. Improved maternal and infant health, better survival in infancy, childhood and early adult life, has led to increase life expectancy of older people. As of 2008, 7% (506 million) of the world's population was aged 65 years and older, an increased of 10.4 million since 2007 (Kinsella K and Wan He 2009). The current pace of population aging varies widely. While developed countries have relatively high proportions of people aged 65 years and over, the most rapid increases in older people are in the developing world. As of 2008, 62% (313 million) of the world's population aged 65 and over lived in developing countries (Kinsella K and Wan He 2009). Many developing countries will be experiencing a sudden rise in the proportion of older people within a single generation, with far less well developed infrastructure. In contrast, most developed countries have had decades to adjust to the changing age structure and this change has been supported by relative economic prosperity.

### **2. Theories of population health change**

The implications of longer life mean increased risk of poor physical function as expounded by the theories of population health change. Four theories have been proposed in discussing the consequences of increased life expectancy in older people.

The expansion of Morbidity/Disability Theory (Gruenberg EM 1977), suggests that the gain in life expectancy in older people is mainly due to technological advances and secondary prevention strategies that have extended the life of older people with disability and underlying illness. This results in living with non-fatal diseases such as vision loss, arthritis, chronic pain and other diseases of old age, therefore living longer means living with more years of disability.

The opposing theory is called the Compression of Morbidity/Disability Theory(Fries 1980; Fries 2005). He suggested that primary prevention strategies modify risk factors for

Physical Function in Older People 5

disability in the literature. Basic ADLs are self-care tasks such as bathing, dressing, grooming and eating (Fried LP and Guralnik 1997). The IADL's are tasks that are physically and cognitively more complicated and difficult but are necessary for independent living in the community such as getting groceries, preparing meals, performing everyday household chores. ADL and IADL are measures of disability that reflect how an individual's limitation

The evaluation of mobility refers to the individual's locomotor system. Mobility disability is a critical component of activities of daily living (Fried LP and Guralnik 1997). Mobility disability is defined as difficulty or dependency in functioning due to decreased walking

The building blocks of restrictions in performing ADLs are termed functional limitations (Guralnik and Luigi 2003). Functional limitations are measures independent of environmental influences, and may explain the changes in functional aspects of health. Functional limitation refers to restriction in physical performance of tasks required for

Physical function is a general term that reflects one's ability to perform mobility tasks, ADLs and IADLs. Throughout this chapter "poor physical function" is used as a general term to

To discuss poor physical function in older people, it is important to have an understanding of the progression that ends with loss of physical function, or the disablement process. The disablement process describes how chronic and acute conditions affect functioning in specific body systems, basic human performance, and people's functioning in necessary, usual, expected, and personally desired roles in society (Verbrugge and Jette 1994). It also describes how personal and environmental factors speed up or slow down this process. There are two major models describing disability and related concepts. This chapter will describe both models. – the Nagi Model (Nagi 1976) and the International Classification of Impairments, Disabilities and Handicaps (ICIDH) (World Health Organization 1980) and its current version, the International Classification of Functioning, Disability and Health (ICF) (World Health Organization 2001) developed by the World Health Organization (WHO).

The pathway proposed by Nagi in 1965 to describe progression from disease to disability is shown in Figure.1. Nagi's disability model is based on four related components that described the sequential steps in the theoretical pathway from disease to disability(Nagi 1976). In the Nagi pathway, *pathology* (e.g. sarcopenia) first leads to *impairment* (e.g. lower extremity weakness) (Steven M Albert and Vicki A Freedman 2010). When lower extremity weakness crosses a certain threshold, *functional limitation* (e.g. slow gait speed) becomes evident (Steven M Albert and Vicki A Freedman 2010). When this happens, a person has a

According to this pathway, *pathology* refers to biochemical and physiological abnormalities that are medically labeled as disease, injury or congenital/developmental conditions (Ferrucci, et al. 2007; Nagi 1976; Verbrugge and Jette 1994). *Impairment* is the consequence

*disability* (e.g. difficulty or needing help with walking across a small room).

interacts with the demands of the environment.

independent living, such as walking, balancing and standing.

refer to physical disability, mobility disability and functional limitation.

ability, manoeuvrability and speed.

**4. The disablement process** 

**4.1 The Nagi disablement model** 

mortality that delays the age-at-onset and progression of disabling diseases. Assuming that maximum life expectancy is fixed, this will result in the time live with disability and disease being compressed into a shorter period before death.

Manton offered a third perspective called the "Dynamic Equilibrium Theory" that combines elements from both the expansion and compression theories (Manton KG 1982). Manton proposes that economic, medical and technical progress reduces mortality as well as having an influence on morbidity/disability. Decrease in mortality rates are accompanied by declines in the incidence and progression of chronic diseases. As a result, years of life gained are assumed to be achieved through a combination of postponement of disease onset, reduction in severity of disease and disease progression due to improvement in clinical management of diseases.

A recent theory takes into consideration the country's position in the demographic transition phase (Robine Jean-Marie and Michel Jean-Pierre 2004). Their "General Theory of Population Aging" encompasses all the three previous theories and relies on a cyclical movement. Firstly, there is an increase in the survival rates of sick people supporting the "expansion of morbidity theory". Second, medical improvements take place, slowing down the progression of chronic condition and achieving certain equilibrium with mortality decline, supporting the "dynamic equilibrium theory". The third phase is improvement in health status and health behaviours of new cohorts of older people, supporting the "compression of morbidity theory". Eventually there will be an emergence of very old and frail populations, which brings back to the starting point, that is, to a new "expansion of morbidity".

#### **3. The language of physical function**

Before further discussion regarding the subject of physical function and its relevance, some definitions are necessary. The definition of the term "disability" and "functional limitation" in this chapter follows the Nagi Disablement Model (Nagi 1976). This model has proven useful as a language used by researchers to delineate the consequences of disease and injury at the levels of body systems, the person and society. The definition of disability encompasses various aspects; pathology, impairment, and limitation are terms that are directly associated with the concept of disability.

According to the classification scheme provided by Nagi, *impairment* refers to a loss or abnormality at the tissue, organ and body system level. At the level of the individual, Nagi uses the term *functional limitations* that represent limitations in performance of specific tasks by a person. The term *disability*, as defined by Nagi, refers to limitations in performing socially defined roles and tasks expected of an individual within a socio-cultural and physical environment. Both impairment and functional limitation involve function. However, for impairment, the reference is to the levels of tissues, organs and systems while for functional limitation, the reference is to the level of the person as a whole. In differentiating functional limitation from disability, functional limitation refers to organismic performance; in contrast disability refers to social performance.

The term physical disability is often used to refer to restrictions in the ability to perform a set of common, everyday tasks, performance of which is required for personal self care and independent living. This includes the basic activities of daily living (ADL) and instrumental activities of daily living (IADL). These are the most widely used measurements of physical

mortality that delays the age-at-onset and progression of disabling diseases. Assuming that maximum life expectancy is fixed, this will result in the time live with disability and disease

Manton offered a third perspective called the "Dynamic Equilibrium Theory" that combines elements from both the expansion and compression theories (Manton KG 1982). Manton proposes that economic, medical and technical progress reduces mortality as well as having an influence on morbidity/disability. Decrease in mortality rates are accompanied by declines in the incidence and progression of chronic diseases. As a result, years of life gained are assumed to be achieved through a combination of postponement of disease onset, reduction in severity of disease and disease progression due to improvement in clinical

A recent theory takes into consideration the country's position in the demographic transition phase (Robine Jean-Marie and Michel Jean-Pierre 2004). Their "General Theory of Population Aging" encompasses all the three previous theories and relies on a cyclical movement. Firstly, there is an increase in the survival rates of sick people supporting the "expansion of morbidity theory". Second, medical improvements take place, slowing down the progression of chronic condition and achieving certain equilibrium with mortality decline, supporting the "dynamic equilibrium theory". The third phase is improvement in health status and health behaviours of new cohorts of older people, supporting the "compression of morbidity theory". Eventually there will be an emergence of very old and frail populations, which brings back to the starting

Before further discussion regarding the subject of physical function and its relevance, some definitions are necessary. The definition of the term "disability" and "functional limitation" in this chapter follows the Nagi Disablement Model (Nagi 1976). This model has proven useful as a language used by researchers to delineate the consequences of disease and injury at the levels of body systems, the person and society. The definition of disability encompasses various aspects; pathology, impairment, and limitation are terms that are

According to the classification scheme provided by Nagi, *impairment* refers to a loss or abnormality at the tissue, organ and body system level. At the level of the individual, Nagi uses the term *functional limitations* that represent limitations in performance of specific tasks by a person. The term *disability*, as defined by Nagi, refers to limitations in performing socially defined roles and tasks expected of an individual within a socio-cultural and physical environment. Both impairment and functional limitation involve function. However, for impairment, the reference is to the levels of tissues, organs and systems while for functional limitation, the reference is to the level of the person as a whole. In differentiating functional limitation from disability, functional limitation refers to

The term physical disability is often used to refer to restrictions in the ability to perform a set of common, everyday tasks, performance of which is required for personal self care and independent living. This includes the basic activities of daily living (ADL) and instrumental activities of daily living (IADL). These are the most widely used measurements of physical

organismic performance; in contrast disability refers to social performance.

being compressed into a shorter period before death.

point, that is, to a new "expansion of morbidity".

directly associated with the concept of disability.

**3. The language of physical function** 

management of diseases.

disability in the literature. Basic ADLs are self-care tasks such as bathing, dressing, grooming and eating (Fried LP and Guralnik 1997). The IADL's are tasks that are physically and cognitively more complicated and difficult but are necessary for independent living in the community such as getting groceries, preparing meals, performing everyday household chores. ADL and IADL are measures of disability that reflect how an individual's limitation interacts with the demands of the environment.

The evaluation of mobility refers to the individual's locomotor system. Mobility disability is a critical component of activities of daily living (Fried LP and Guralnik 1997). Mobility disability is defined as difficulty or dependency in functioning due to decreased walking ability, manoeuvrability and speed.

The building blocks of restrictions in performing ADLs are termed functional limitations (Guralnik and Luigi 2003). Functional limitations are measures independent of environmental influences, and may explain the changes in functional aspects of health. Functional limitation refers to restriction in physical performance of tasks required for independent living, such as walking, balancing and standing.

Physical function is a general term that reflects one's ability to perform mobility tasks, ADLs and IADLs. Throughout this chapter "poor physical function" is used as a general term to refer to physical disability, mobility disability and functional limitation.

#### **4. The disablement process**

To discuss poor physical function in older people, it is important to have an understanding of the progression that ends with loss of physical function, or the disablement process. The disablement process describes how chronic and acute conditions affect functioning in specific body systems, basic human performance, and people's functioning in necessary, usual, expected, and personally desired roles in society (Verbrugge and Jette 1994). It also describes how personal and environmental factors speed up or slow down this process. There are two major models describing disability and related concepts. This chapter will describe both models. – the Nagi Model (Nagi 1976) and the International Classification of Impairments, Disabilities and Handicaps (ICIDH) (World Health Organization 1980) and its current version, the International Classification of Functioning, Disability and Health (ICF) (World Health Organization 2001) developed by the World Health Organization (WHO).

#### **4.1 The Nagi disablement model**

The pathway proposed by Nagi in 1965 to describe progression from disease to disability is shown in Figure.1. Nagi's disability model is based on four related components that described the sequential steps in the theoretical pathway from disease to disability(Nagi 1976). In the Nagi pathway, *pathology* (e.g. sarcopenia) first leads to *impairment* (e.g. lower extremity weakness) (Steven M Albert and Vicki A Freedman 2010). When lower extremity weakness crosses a certain threshold, *functional limitation* (e.g. slow gait speed) becomes evident (Steven M Albert and Vicki A Freedman 2010). When this happens, a person has a *disability* (e.g. difficulty or needing help with walking across a small room).

According to this pathway, *pathology* refers to biochemical and physiological abnormalities that are medically labeled as disease, injury or congenital/developmental conditions (Ferrucci, et al. 2007; Nagi 1976; Verbrugge and Jette 1994). *Impairment* is the consequence

Physical Function in Older People 7

Source: Verbrugge LM, Jette AM. The disablement process. Social Science and Medicine; 1994: 38(1): 1-

interaction between the organism and the environment and is defined as any change or restriction in an individual's goal-directed behaviour (Ferrucci, et al. 2007; Verbrugge and Jette 1994). Finally, handicap is defined as any alteration in a person's status in society, including alterations in roles. Each level of the pathway should be considered as independent and may or may not be determined by the previous level and/or cause the

14

Fig. 2. The Disablement Process (1994)

and degree of pathology (Nagi 1976; Verbrugge and Jette 1994). *Functional limitations* are limitations in performance at the level of the whole organism or person (Ferrucci, et al. 2007). By contrast, *disability* is defined as limitation in performance of socially defined roles and tasks within a socio-cultural and physical environment(Ferrucci, et al. 2007). Disability can also refer to the expression of functional limitation in a social context. An important advantage of utilizing different definitions for functional limitation and disability, as proposed by Nagi, is that they can be considered as sequential steps on the pathway from disease to disability. The validity of this theoretical pathway is supported by a large body of literature (Ferrucci, et al. 2007; Fried and Guralnik 1997; Steven M Albert and Vicki A Freedman 2010). Practical issues of care and prevention can be addressed by utilizing this pathway.

Source: Nagi S. An epidemiology of disability among adults in the United States. The Milbank Memorial Fund Quarterly. Health and Society. 1976; 54: 439-467

Fig. 1. Theoretical pathway from disease to disability proposed by Nagi (1965)

Nagi's model was extended to include personal and environmental factors that influence the evolution of the disablement process (Verbrugge and Jette 1994). Verbrugge and Jette differentiate the "main pathways" of the disablement process (i.e. Nagi's original concepts) with factors hypothesized or known to influence the ongoing process of disablement (Figure 2). This model emphasizes that predisposing risk factors, intra-individual and extraindividual factors may modify the relationship of the four components in the main pathway(Ferrucci, et al. 2007; Guralnik and Luigi 2003; Steven M Albert and Vicki A Freedman 2010; Verbrugge and Jette 1994). Risk factors are predisposing phenomena that are present prior to the onset of a disabling event that can affect the presence and/or severity of the disablement process. Intra-individual factors are those that operate within a person such as lifestyle and behavioural changes, psychosocial attributes and coping skills. Extra-individual factors are those that perform outside or external to the person. Nagi's definition of disability and the elaboration by Verbrugge and Jette also operationalizes disability as a broad range of role behaviours that are relevant to daily activities. This includes basic ADL, IADL, paid and unpaid role activities, such as occupation, social activities and leisure activities.

#### **4.2 World Health Organization's models of disablement**

In 1980, the World Health Organization (WHO) proposed a theoretical framework to describe the sequence from disease/disorder to impairment, disability and handicap named the International Classification of Impairments, Disabilities and Handicaps (ICIDH) (World Health Organization 1980)(Figure 3). At the foundation of the pathway is pathology, which is defined as any abnormality of macroscopic, microscopic or biochemical structure or function affecting an organ or organ system (Ferrucci, et al. 2007; Verbrugge and Jette 1994). The second step is impairment, defined as any abnormality of structure or function at the whole organism level, independent of any specific environment, symptom, or sign (Ferrucci, et al. 2007; Verbrugge and Jette 1994). At the third step is disability, which derives from the

and degree of pathology (Nagi 1976; Verbrugge and Jette 1994). *Functional limitations* are limitations in performance at the level of the whole organism or person (Ferrucci, et al. 2007). By contrast, *disability* is defined as limitation in performance of socially defined roles and tasks within a socio-cultural and physical environment(Ferrucci, et al. 2007). Disability can also refer to the expression of functional limitation in a social context. An important advantage of utilizing different definitions for functional limitation and disability, as proposed by Nagi, is that they can be considered as sequential steps on the pathway from disease to disability. The validity of this theoretical pathway is supported by a large body of literature (Ferrucci, et al. 2007; Fried and Guralnik 1997; Steven M Albert and Vicki A Freedman 2010). Practical issues of care and prevention can be addressed by utilizing this

Limitation

Disability

Pathology Impairment Functional

Memorial Fund Quarterly. Health and Society. 1976; 54: 439-467

**4.2 World Health Organization's models of disablement** 

Source: Nagi S. An epidemiology of disability among adults in the United States. The Milbank

Nagi's model was extended to include personal and environmental factors that influence the evolution of the disablement process (Verbrugge and Jette 1994). Verbrugge and Jette differentiate the "main pathways" of the disablement process (i.e. Nagi's original concepts) with factors hypothesized or known to influence the ongoing process of disablement (Figure 2). This model emphasizes that predisposing risk factors, intra-individual and extraindividual factors may modify the relationship of the four components in the main pathway(Ferrucci, et al. 2007; Guralnik and Luigi 2003; Steven M Albert and Vicki A Freedman 2010; Verbrugge and Jette 1994). Risk factors are predisposing phenomena that are present prior to the onset of a disabling event that can affect the presence and/or severity of the disablement process. Intra-individual factors are those that operate within a person such as lifestyle and behavioural changes, psychosocial attributes and coping skills. Extra-individual factors are those that perform outside or external to the person. Nagi's definition of disability and the elaboration by Verbrugge and Jette also operationalizes disability as a broad range of role behaviours that are relevant to daily activities. This includes basic ADL, IADL, paid and unpaid role activities, such as occupation, social

In 1980, the World Health Organization (WHO) proposed a theoretical framework to describe the sequence from disease/disorder to impairment, disability and handicap named the International Classification of Impairments, Disabilities and Handicaps (ICIDH) (World Health Organization 1980)(Figure 3). At the foundation of the pathway is pathology, which is defined as any abnormality of macroscopic, microscopic or biochemical structure or function affecting an organ or organ system (Ferrucci, et al. 2007; Verbrugge and Jette 1994). The second step is impairment, defined as any abnormality of structure or function at the whole organism level, independent of any specific environment, symptom, or sign (Ferrucci, et al. 2007; Verbrugge and Jette 1994). At the third step is disability, which derives from the

Fig. 1. Theoretical pathway from disease to disability proposed by Nagi (1965)

pathway.

activities and leisure activities.

Source: Verbrugge LM, Jette AM. The disablement process. Social Science and Medicine; 1994: 38(1): 1- 14

Fig. 2. The Disablement Process (1994)

interaction between the organism and the environment and is defined as any change or restriction in an individual's goal-directed behaviour (Ferrucci, et al. 2007; Verbrugge and Jette 1994). Finally, handicap is defined as any alteration in a person's status in society, including alterations in roles. Each level of the pathway should be considered as independent and may or may not be determined by the previous level and/or cause the

Physical Function in Older People 9

This framework starts with the concept of *health conditions*, which includes diseases, disorders, injuries and trauma. *Impairments* may occur to either body functions (e.g. reduce walking speed) or body structures (e.g. narrowing of a heart valve) (World Health Organization 2001). *Activity limitations* are difficulties an individual may have in executing activities relating to mobility, self care or domestic life (Jette AM and Keysor J 2003). *Participation restrictions* are problems an individual may experience. Disability and functioning are defined as umbrella terms (Marilyn J. Field and Alan M. Jette 2007). In the pictorial representation of the ICF (Figure 4), the terms disability and functioning do not exist. Disability and functioning are considered outcomes of interactions between health

Source: World Health Organization. International Classification of Functioning, Disability and Health.

The first element of the ICF, the Body Functions and Structures is similar to Nagi's concept of pathology and impairment while the second component of the ICF, the Activities and Participation closely corresponds to Nagi's concept of functional limitations and disability (Jette AM and Keysor J 2003)(as shown in Table 2). The greatest limitations of the ICF is the aggregation of "activities and participation" into one domain (Guralnik and Ferrucci 2009). Using the ICF, the concepts of activity limitation and participation restriction are difficult to separate, unlike Nagi's concept of functional limitations and disability. The ICF currently does not offer crisp distinction between activity and participation, although there is an increasing movement towards defining "activities" and "participation". The Institute of Medicine (IOM) discussed this concern in its report entitled Future of Disability in America (Marilyn J. Field and Alan M. Jette 2007). Some sections of the report cited verbatim are as

*"A first and well recognized aspect of the ICF that needs further development involves the* 

*interpretation and categorization of the concepts of activity and participation (page 42)"* 

Fig. 4. The International Classification of Functioning, Disability and Health (ICF) 2001

conditions and contextual factors.

Geneva. WHO, 2001.

shown below:

successive level (Ferrucci, et al. 2007; Verbrugge and Jette 1994). This approach raised criticisms for several reasons: it was thought to be too medically-orientated, ignoring social and psychological dimensions; the negative connotation of the term 'handicap'; and the omission of environmental factors. Some of these limitations were overcome by the model proposed by Nagi.

In 2001, the WHO presented a revision of the classification under a new name called the International Classification of Functioning, Disability and Health (ICF) (World Health Organization 2001) (Figure 4). The revised model moves away from the idea that disability is a consequence of disease or aging and focuses on components of health as human functioning. The ICF has two parts, each with two components (Table 1). Part One is entitled Functioning and Disability (which includes body functions and structures, activities and participation). Part Two is entitled Contextual Factors, which includes environmental factors and personal factors.

Source: World Health Organization. International Classification of Impairments, Disabilities and Handicaps: A Manual Classification Relating to the Consequences of Diseases. Geneva. WHO, 1980.



Source: World Health Organization. International Classification of Functioning, Disability and Health (ICF). Geneva. WHO, 2001.

Table 1. An overview of International Classification of Functioning, Disability and Health (ICF)

successive level (Ferrucci, et al. 2007; Verbrugge and Jette 1994). This approach raised criticisms for several reasons: it was thought to be too medically-orientated, ignoring social and psychological dimensions; the negative connotation of the term 'handicap'; and the omission of environmental factors. Some of these limitations were overcome by the model

In 2001, the WHO presented a revision of the classification under a new name called the International Classification of Functioning, Disability and Health (ICF) (World Health Organization 2001) (Figure 4). The revised model moves away from the idea that disability is a consequence of disease or aging and focuses on components of health as human functioning. The ICF has two parts, each with two components (Table 1). Part One is entitled Functioning and Disability (which includes body functions and structures, activities and participation). Part Two is entitled Contextual Factors, which includes environmental factors

Source: World Health Organization. International Classification of Impairments, Disabilities and Handicaps: A Manual Classification Relating to the Consequences of Diseases. Geneva. WHO, 1980. Fig. 3. The International Classification of Impairments, Disabilities and Handicaps Model

 **Part 1 : Functioning and Disability Part 2: Contextual Factors** 

**Activities and** 

Life areas (tasks, actions)

Capacity: executing tasks in a standard environment Performance: executing tasks in the current environment

Activities and

Activity limitation Participation restriction

Source: World Health Organization. International Classification of Functioning, Disability and Health

Table 1. An overview of International Classification of Functioning, Disability and Health

Impairments Disabilities Handicaps

**participation Environmental factors Personal factors** 

Internal influences on functioning and disability

Impact of attributes of the person

External influences on functioning and disability

Facilitating or hindering impact of features of the physical, social, and attitudinal world

Participation Facilitators Not applicable

Barriers/hindrances Not applicable

proposed by Nagi.

and personal factors.

 Disease or Disorder

(ICIDH), 1980

Constructs

**Component Body functions** 

Domains Body functions

Positive aspect Functional and

Negative aspect Impairment

(ICF). Geneva. WHO, 2001.

(ICF)

**and structures** 

Body structures

Change in body functions (physiological) Change in body structure (anatomical)

structural integrity

This framework starts with the concept of *health conditions*, which includes diseases, disorders, injuries and trauma. *Impairments* may occur to either body functions (e.g. reduce walking speed) or body structures (e.g. narrowing of a heart valve) (World Health Organization 2001). *Activity limitations* are difficulties an individual may have in executing activities relating to mobility, self care or domestic life (Jette AM and Keysor J 2003). *Participation restrictions* are problems an individual may experience. Disability and functioning are defined as umbrella terms (Marilyn J. Field and Alan M. Jette 2007). In the pictorial representation of the ICF (Figure 4), the terms disability and functioning do not exist. Disability and functioning are considered outcomes of interactions between health conditions and contextual factors.

Source: World Health Organization. International Classification of Functioning, Disability and Health. Geneva. WHO, 2001.

Fig. 4. The International Classification of Functioning, Disability and Health (ICF) 2001

The first element of the ICF, the Body Functions and Structures is similar to Nagi's concept of pathology and impairment while the second component of the ICF, the Activities and Participation closely corresponds to Nagi's concept of functional limitations and disability (Jette AM and Keysor J 2003)(as shown in Table 2). The greatest limitations of the ICF is the aggregation of "activities and participation" into one domain (Guralnik and Ferrucci 2009). Using the ICF, the concepts of activity limitation and participation restriction are difficult to separate, unlike Nagi's concept of functional limitations and disability. The ICF currently does not offer crisp distinction between activity and participation, although there is an increasing movement towards defining "activities" and "participation". The Institute of Medicine (IOM) discussed this concern in its report entitled Future of Disability in America (Marilyn J. Field and Alan M. Jette 2007). Some sections of the report cited verbatim are as shown below:

*"A first and well recognized aspect of the ICF that needs further development involves the interpretation and categorization of the concepts of activity and participation (page 42)"* 

Physical Function in Older People 11

disability, self report and proxy report of difficulty or inability to perform ADLs and IADLs and mobility questionnaires have been the standard assessment tools (Guralnik and Luigi 2003; Kovar and Lawton 1994). There are more than 100 published basic ADL or IADL scales, with considerable variations in the number of questions, item content, and scoring method. Examples of some of the instruments used to measure disability include Katz ADL, The Barthel Index, Instrumental Activities of Daily Living Scale (IADL), and The Health Assessment Questionnaire (HAQ) Disability Scale. The comparison of the quality of the physical disability and mobility disability tools is as shown in Table 3. Objective measurements of disability are also available but are rarely used (Cress ME 1996; Kuriansky JB 1976). Recently, Cress *et al* have created the Continuous Scale-Physical Functional Performance (CS-PFP) test, a directly observed disability test battery done in a home and neighbourhood-like setting that includes items such as transferring clothes from a washer to

Similarly, functional limitation may be accessed through self-report, proxy report or through performance based tests. A large number of physical performance measures, either individual tests or batteries of tests, have been developed and many of them assess different aspects of functional limitation. Some examples of performance tests commonly used are the Tinetti Performance Oriented Mobility Assessment Tool, Walking Speed, Functional Independence Measure and Timed Up and Go (TUG) test. The comparison of the quality of

All in all, poor physical function has been assessed with a wide variety of instruments. There is no single best way to perform an assessment and there is no single instrument that is ideal. The lack of standardization that results from the use of multiple instruments makes it difficult to compare findings across studies (Jette 1994; Kovar and Lawton 1994; Wiener, et al. 1990).

**6.1 Prevalence of physical disability, mobility disability and functional limitation in** 

disability, mobility disability and functional limitation among older people.

Several studies in developed countries have sought to gauge the prevalence of physical

The basic set of either the six-item ADL or the five-item ADL has been found to be most useful for valid comparison across studies. Using the six-item ADL, the prevalence of disability from the National Long-Term Care Survey in the United States ranges from 12.4% to 13.2 % from 1982 to 2005 (Lafortune 2007). Disability surveys that capture five-item ADL show lower prevalence of disability:- 6% in Canada, 10% in France and 11% in Sweden (Lafortune 2007). Using the five-item ADL, significant variations in disability have been reported between populations in the United States, China and Singapore (Chen, et al. 1995; Ng, et al. 2006; Wiener, et al. 1990; Zhe, et al. 1999). In the United States, the prevalence of five-item ADL among older people aged 65 years and over was 8.1% in the 1987 National Medical Expenditure Survey, 5.8% in the 1984 Survey on Income and Program Participation and 5.0% in the Supplement on Ageing Survey. In Asia, the prevalence of five-item ADL among older people aged 65 years and over was: 8.3% among Shanghai Chinese in the 1987 Shanghai Survey of Alzheimer's Disease and Dementia, and 6.6% among Singaporeans in

a dryer, vacuuming, making a bed and loading and carrying groceries.

the functional limitation tools is as shown in Table 4.

**6. Prevalence of poor physical function** 

the 2003 National Mental Health Survey of the Elderly.

**developed countries** 

*"Several researchers have criticised the lack of clear operational differentiation between the concepts of activity and participation in the ICF as theoretically confusing and a step backward from earlier disability frameworks. Operational differentiation among concepts and the ability to measure each concept precisely and distinctly is important for clear communication, monitoring and research. (page 43)"* 

*"Although this committee does not endorse any particular approach to resolving the problem, it believes that the lack of operational differentiation between the concepts of activity and participation is a significant deficit in the ICF. (page 44)"* 

Since the ICF's distinction between activity and participation is still in the developmental stage, many studies have used the Nagi Disablement Model as a conceptual framework in their research to understand the dynamic relationships among factors associated with physical function. Furthermore, the ICF is not inherently a dynamic model, similar to the ICD-10, the ICF is a classification system that offers standardized internationally accepted language. It is also worth noting that the Nagi Disablement Model has been successfully used as a theoretical pathway that was empirically tested in many datasets (Guralnik and Ferrucci 2009). For example, evidence demonstrates the predictive value of disease for impairment (arthritis causing reduced strength) (Guralnik and Luigi 2003), of impairment for functional limitations (reduced strength leading to reduced gait speed) (Guralnik and Ferrucci 2009) and of functional limitations for disability (lower extremity limitations leading to activity of daily living and mobility disability) (Penninx, et al. 2000).


Source: Jette AM, Keysor J. Disability Models: Implications for Arthritis Exercise and Physical Activity Interventions. Arthritis and Rheumatisn (Arthris Care and Research), 2003: 49; 114-120.

Table 2. The Disablement Model and the International Classification of Functioning, Disability and Health (ICF) frameworks.

#### **5. Physical function measurement tools**

Poor physical function can be assessed by using instruments based on self-report and by objective measurements or performance based tests. In the domain of physical and mobility

*"Several researchers have criticised the lack of clear operational differentiation between the concepts of activity and participation in the ICF as theoretically confusing and a step backward from earlier disability frameworks. Operational differentiation among concepts and the ability to measure each concept precisely and distinctly is important for clear communication, monitoring and research.* 

*"Although this committee does not endorse any particular approach to resolving the problem, it believes that the lack of operational differentiation between the concepts of activity and participation* 

Since the ICF's distinction between activity and participation is still in the developmental stage, many studies have used the Nagi Disablement Model as a conceptual framework in their research to understand the dynamic relationships among factors associated with physical function. Furthermore, the ICF is not inherently a dynamic model, similar to the ICD-10, the ICF is a classification system that offers standardized internationally accepted language. It is also worth noting that the Nagi Disablement Model has been successfully used as a theoretical pathway that was empirically tested in many datasets (Guralnik and Ferrucci 2009). For example, evidence demonstrates the predictive value of disease for impairment (arthritis causing reduced strength) (Guralnik and Luigi 2003), of impairment for functional limitations (reduced strength leading to reduced gait speed) (Guralnik and Ferrucci 2009) and of functional limitations for disability (lower extremity limitations

leading to activity of daily living and mobility disability) (Penninx, et al. 2000).

Model Pathology Impairment Functional

Physiological functions of body systems and anatomical parts of body

Interventions. Arthritis and Rheumatisn (Arthris Care and Research), 2003: 49; 114-120.

Table 2. The Disablement Model and the International Classification of Functioning,

**Physiological functions of the body** 

Dysfunctions and structural abnormalities in specific body systems

ICF Body Functions and Structures Activities and Participation

Source: Jette AM, Keysor J. Disability Models: Implications for Arthritis Exercise and Physical Activity

Poor physical function can be assessed by using instruments based on self-report and by objective measurements or performance based tests. In the domain of physical and mobility

**Task performance** 

Restrictions in basic physical actions

Limitations Disability

Activity : Execution of a tasks or action Participation: Involvement in a life situation

**Involvement in life roles** 

The expression of a physical limitation in a social context

**Anatomical body parts** 

Disease, injury, congenital condition

Disability and Health (ICF) frameworks.

**5. Physical function measurement tools** 

*(page 43)"* 

Disablement

*is a significant deficit in the ICF. (page 44)"* 

disability, self report and proxy report of difficulty or inability to perform ADLs and IADLs and mobility questionnaires have been the standard assessment tools (Guralnik and Luigi 2003; Kovar and Lawton 1994). There are more than 100 published basic ADL or IADL scales, with considerable variations in the number of questions, item content, and scoring method. Examples of some of the instruments used to measure disability include Katz ADL, The Barthel Index, Instrumental Activities of Daily Living Scale (IADL), and The Health Assessment Questionnaire (HAQ) Disability Scale. The comparison of the quality of the physical disability and mobility disability tools is as shown in Table 3. Objective measurements of disability are also available but are rarely used (Cress ME 1996; Kuriansky JB 1976). Recently, Cress *et al* have created the Continuous Scale-Physical Functional Performance (CS-PFP) test, a directly observed disability test battery done in a home and neighbourhood-like setting that includes items such as transferring clothes from a washer to a dryer, vacuuming, making a bed and loading and carrying groceries.

Similarly, functional limitation may be accessed through self-report, proxy report or through performance based tests. A large number of physical performance measures, either individual tests or batteries of tests, have been developed and many of them assess different aspects of functional limitation. Some examples of performance tests commonly used are the Tinetti Performance Oriented Mobility Assessment Tool, Walking Speed, Functional Independence Measure and Timed Up and Go (TUG) test. The comparison of the quality of the functional limitation tools is as shown in Table 4.

All in all, poor physical function has been assessed with a wide variety of instruments. There is no single best way to perform an assessment and there is no single instrument that is ideal. The lack of standardization that results from the use of multiple instruments makes it difficult to compare findings across studies (Jette 1994; Kovar and Lawton 1994; Wiener, et al. 1990).

#### **6. Prevalence of poor physical function**

#### **6.1 Prevalence of physical disability, mobility disability and functional limitation in developed countries**

Several studies in developed countries have sought to gauge the prevalence of physical disability, mobility disability and functional limitation among older people.

The basic set of either the six-item ADL or the five-item ADL has been found to be most useful for valid comparison across studies. Using the six-item ADL, the prevalence of disability from the National Long-Term Care Survey in the United States ranges from 12.4% to 13.2 % from 1982 to 2005 (Lafortune 2007). Disability surveys that capture five-item ADL show lower prevalence of disability:- 6% in Canada, 10% in France and 11% in Sweden (Lafortune 2007). Using the five-item ADL, significant variations in disability have been reported between populations in the United States, China and Singapore (Chen, et al. 1995; Ng, et al. 2006; Wiener, et al. 1990; Zhe, et al. 1999). In the United States, the prevalence of five-item ADL among older people aged 65 years and over was 8.1% in the 1987 National Medical Expenditure Survey, 5.8% in the 1984 Survey on Income and Program Participation and 5.0% in the Supplement on Ageing Survey. In Asia, the prevalence of five-item ADL among older people aged 65 years and over was: 8.3% among Shanghai Chinese in the 1987 Shanghai Survey of Alzheimer's Disease and Dementia, and 6.6% among Singaporeans in the 2003 National Mental Health Survey of the Elderly.




Physical Function in Older People 15


14 Geriatrics


Table 3. Comparison of the physical disability and mobility disability assessment tools

Physical Function in Older People 17


Table 3. Comparison of the physical disability and mobility disability assessment tools


Table 4. Comparison of the functional limitation assessment tools.

Physical Function in Older People 19

Mobility disability is very common among older people. Results from a United States National Prevalence Survey of Disability revealed that among older people aged 65 years and over, 30% had difficulty with mobility (Nordstrom, et al. 2007). In the United Kingdom, the Hertfordshire Cohort Study found that 32% of men and 46% of women aged 59 years and over reported that their health limited them in performing mobility activities (Syddall, et al. 2009). Data from the Netherlands National Health Survey showed that approximately 18% and 37% of older Dutch people aged 65 to 74 years and 75 years and over respectively

Assessing functional limitation adds valuable information about the steps in the disability pathway. Gait speed, often termed walking speed has been regarded as the best single measure to evaluate functional limitation (Guralnik and Luigi 2003). It has also shown to be a strong and consistent predictor of adverse outcomes in older people. In a pooled analysis of individual data from nine major cohorts, gait speed has been shown to be a predictor of mortality in older people (Studenski, et al. 2011). In the same study, Studenski standardized the method to assess gait speed from different lengths (8 feet, 4 meters, or 6 meters) to a 4 meter-long track starting from a still, standing position. Using a recommended cut-off point of 0.8 meter/second as increased likelihood of poor health and function, the percentages of older people with poor mobility were : 44.2% in the Cardiovascular Health Study, 40.8% in the Established Populations for Epidemiologic Studies of the Elderly (EPESE), 84.1% in the Hispanic EPESE, 69.4% in the National Health and Nutrition Examination Survey III (NHANES III), 34.6% in the Predicting Early Performance Study and 21% in the InCHIANTI

**6.2 Prevalence of physical disability, mobility disability and functional limitation in** 

The burden of poor physical function has been studied extensively in developed countries but there is little data available for older people in developing countries. Comparison of physical disability, mobility disability and functional limitation distribution between countries is difficult due to methodological differences in definition and measurements used. Surveys from around the world used different approaches in measuring disability. Different instruments within the same country often report different rates. Across countries the variation is even more cumbersome. Nevertheless, the studies discussed below used

Prevalence studies on the five-item ADL disability among older people had been carried out in several low income developing countries. The Cambodian study in 2004 showed a prevalence of 23.7% among older people aged 60 years and over (Zimmer 2008); the 1998 Housing and Population Census of the Ethiopian Government reported a prevalence of 28.6% among Ethiopians adults aged 55 years and above (Teferra 2005). In addition, two studies were conducted in Nepal among older people aged 60 years and above with prevalence of 8.8% in Kathmandu city, 2005 and a much higher prevalence of 55.8% in rural

Studies on the five-item ADL disability among older people in lower middle income developing countries reported varied prevalence: 10% and 9% among older people aged 65 years and over in Sri Lanka (Nugegoda and Balasuriya 1995) and urban Chinese in Shanghai

reported mobility disability (Picavet and Hoeymans 2002).

Study (Invecchiare in Chianti Study) (Studenski, et al. 2011).

**developing countries** 

comparable methods to a certain extent.

Chitwan Valley, 1998 (Shrestha 2004).

Table 4. Comparison of the functional limitation assessment tools.

Mobility disability is very common among older people. Results from a United States National Prevalence Survey of Disability revealed that among older people aged 65 years and over, 30% had difficulty with mobility (Nordstrom, et al. 2007). In the United Kingdom, the Hertfordshire Cohort Study found that 32% of men and 46% of women aged 59 years and over reported that their health limited them in performing mobility activities (Syddall, et al. 2009). Data from the Netherlands National Health Survey showed that approximately 18% and 37% of older Dutch people aged 65 to 74 years and 75 years and over respectively reported mobility disability (Picavet and Hoeymans 2002).

Assessing functional limitation adds valuable information about the steps in the disability pathway. Gait speed, often termed walking speed has been regarded as the best single measure to evaluate functional limitation (Guralnik and Luigi 2003). It has also shown to be a strong and consistent predictor of adverse outcomes in older people. In a pooled analysis of individual data from nine major cohorts, gait speed has been shown to be a predictor of mortality in older people (Studenski, et al. 2011). In the same study, Studenski standardized the method to assess gait speed from different lengths (8 feet, 4 meters, or 6 meters) to a 4 meter-long track starting from a still, standing position. Using a recommended cut-off point of 0.8 meter/second as increased likelihood of poor health and function, the percentages of older people with poor mobility were : 44.2% in the Cardiovascular Health Study, 40.8% in the Established Populations for Epidemiologic Studies of the Elderly (EPESE), 84.1% in the Hispanic EPESE, 69.4% in the National Health and Nutrition Examination Survey III (NHANES III), 34.6% in the Predicting Early Performance Study and 21% in the InCHIANTI Study (Invecchiare in Chianti Study) (Studenski, et al. 2011).

#### **6.2 Prevalence of physical disability, mobility disability and functional limitation in developing countries**

The burden of poor physical function has been studied extensively in developed countries but there is little data available for older people in developing countries. Comparison of physical disability, mobility disability and functional limitation distribution between countries is difficult due to methodological differences in definition and measurements used. Surveys from around the world used different approaches in measuring disability. Different instruments within the same country often report different rates. Across countries the variation is even more cumbersome. Nevertheless, the studies discussed below used comparable methods to a certain extent.

Prevalence studies on the five-item ADL disability among older people had been carried out in several low income developing countries. The Cambodian study in 2004 showed a prevalence of 23.7% among older people aged 60 years and over (Zimmer 2008); the 1998 Housing and Population Census of the Ethiopian Government reported a prevalence of 28.6% among Ethiopians adults aged 55 years and above (Teferra 2005). In addition, two studies were conducted in Nepal among older people aged 60 years and above with prevalence of 8.8% in Kathmandu city, 2005 and a much higher prevalence of 55.8% in rural Chitwan Valley, 1998 (Shrestha 2004).

Studies on the five-item ADL disability among older people in lower middle income developing countries reported varied prevalence: 10% and 9% among older people aged 65 years and over in Sri Lanka (Nugegoda and Balasuriya 1995) and urban Chinese in Shanghai

Physical Function in Older People 21

There are few reports of ethnic differences in frequency of poor physical function. How differences in sociodemographic and health-related factors explain the ethnic differences in poor physical function is still unclear. Older black and Hispanic Americans have a higher prevalence of poor physical function than their white counterparts (Kelly-Moore and Ferraro 2004). Other studies from the United States have found that African-American have higher disability rates compared to the Whites even after adjustment for education (Liao, et al. 1999) and chronic disease (Kingston and Smith 1997), although one study reported that social and health factors explained these differences(Kelly-Moore and Ferraro 2004). Ng *et al* showed that Indians and Malays in Singapore have higher risk of disability than

Older people in less advantaged socioeconomic positions report more physical disability, mobility disability and functional limitation. Lower level of education tends to be associated with a higher prevalence of poor physical function at all ages(Lafortune 2007). A lower level of education is often associated with lower income, lower standards of living, higher risk of work-related injuries, and adoption of less healthy behaviours. The "education" effect has

Changes in the prevalence of chronic diseases play a dominant role in explaining the prevalence of poor physical function among older people. However, not all diseases are associated with poor physical function and some are more strongly associated than others. Diseases with large effects on poor physical function include stroke and other neurological diseases, diabetes, heart diseases, depression, arthritis and other musculoskeletal diseases(Avlund 2004). It has also been reported that the presence of more than one chronic disease in an individual, often called co-morbidity is associated with poor physical function(Guralnik, et al. 1993; Schmitz, et al. 2007). Guralnik *et al* showed that the presence of a single chronic disease is a significant predictor of poor physical function, with the risk increasing incrementally up to the presence of four or

There is also some evidence of association between smoking, heavy alcohol consumption

The majority of studies on risk factors for poor physical function have focused on chronic diseases and lifestyle behaviours. There are a number of health-related factors that have rarely been investigated. These include the co-existence of depression and visual impairment; chronic pain; and the role of muscle strength, muscle mass (sarcopenia) and

**7.2 Co-existing depressive symptoms and visual impairment as risk factors of poor** 

The accumulation of deficits across more than one health domain, including physiological, sensory, cognitive and psychological domain, is likely to explain the development of poor physical function better than decline in just one single health domain. Whitson *et a*l showed that individuals with co-existing visual impairment and cognitive impairment are at high risk of disability(Whitson, et al. 2007). Lin *et al* showed that that the burden of having both vision and hearing impairment is greater than the sum of each single impairment(Lin, et al. 2004). Rantanen *at al* reported that the odds of severe mobility disability were ten times

and lack of physical activity with poor physical function(Tas, et al. 2007b).

Singaporean Chinese (Ng, et al. 2006).

more chronic diseases(Guralnik, et al. 1993).

muscle quality.

**physical function** 

been shown to be a proxy for broader "socioeconomic status".

(Chen, et al. 1995)respectively. Whereas, among older people aged 60 years and over, the prevalence were: 12% in Indians(Shantibala, et al. 2007), 10.9% and 14.7% in Filipinos in the years 1996 and 2001 respectively (Ofstedal et al), 6.5% in Beijing Chinese (Zhe, et al. 1999), 18.7% in Indonesian men and 12.1% in Indonesian women (Evi Nurvidya Arifin 2009).

Several studies in lower middle income countries have used six-item ADL scales. In the WHO Collaborative Study on Social and Health Aspects of Aging in 1990, the prevalence of six item ADL disability among older people age 60 and over was: 22.4% in Egyptian men, 28.5% in Egyptian women, 32.0% in Tunisian men and 46.8% in Tunisian women (Yount and Agree 2005). The Ibadan Study of Aging in Nigeria in 2004 reported the prevalence of six-item ADL disability at only 3% among Nigerians aged 65 years and over(Oye Gureje, et al. 2006). The prevalence of disability among Nigerians is low because of the difference in criterion definition used. In the Ibadan Study of Aging, disability is based on difficulty experience with four levels of responses. This resulted in a more restrictive definition of disability, as compared to studies that defined disability based on any level of difficulty.

Many studies on the prevalence of physical disability were conducted in upper middle income countries. From the Survey on Health and Well-Being of Elders. Palloni *et al* reported that the prevalence of six-item ADL disability among older people were: 19% in Argentina, 14% in Barbados, 24% in Brazil, 26% in Chile, 21% in Cuba, 19% in Mexico and 17% in Uruguay (Palloni and McEniry 2007). The prevalence of six-item ADL disability among older people aged 60 years and over in Puerto Rico in a 2003 study was 20%(Palloni, et al. 2005).

The epidemiology of poor physical function among older people in developing countries is incompletely understood with many unanswered questions.

#### **7. Risk factors for poor physical function**

Several factors have been identified as risk factors for disability and functional limitation. These include non-modifiable risk factors (e.g. gender, ethnicity and genetics) and modifiable risk factors, which include both individual factors (such as sedentary lifestyle, unhealthy behaviours) as well as characteristics of the environment (e.g. household hazards, disadvantaged neighbourhood conditions, common forms of transportation).

#### **7.1 Gender, ethnic group, socioeconomic and health-related factors**

Poor physical function had been reported to be associated with increasing age(Tas, et al. 2007a), being female(Tas, et al. 2007a), lower socioeconomic status(Tas, et al. 2007a), chronic diseases(Tas, et al. 2007a), depression (Tas, et al. 2007a), visual impairment(Ng, et al. 2006), cognitive impairment(Ng, et al. 2006), poor self rated health(Ng, et al. 2006), fewer social support(Tas, et al. 2007b), living alone(Ng, et al. 2006) and lack of exercise(Wu, et al. 1999).

The association between female gender and poor physical function is consistently reported in many studies. Some studies have shown that the higher prevalence of poor physical function in female is unexplainable by known differences in sociodemographic and health related factors(Auxiliadora Graciani, et al. 2004; Dunlop, et al. 1997).

(Chen, et al. 1995)respectively. Whereas, among older people aged 60 years and over, the prevalence were: 12% in Indians(Shantibala, et al. 2007), 10.9% and 14.7% in Filipinos in the years 1996 and 2001 respectively (Ofstedal et al), 6.5% in Beijing Chinese (Zhe, et al. 1999), 18.7% in Indonesian men and 12.1% in Indonesian women (Evi Nurvidya Arifin 2009).

Several studies in lower middle income countries have used six-item ADL scales. In the WHO Collaborative Study on Social and Health Aspects of Aging in 1990, the prevalence of six item ADL disability among older people age 60 and over was: 22.4% in Egyptian men, 28.5% in Egyptian women, 32.0% in Tunisian men and 46.8% in Tunisian women (Yount and Agree 2005). The Ibadan Study of Aging in Nigeria in 2004 reported the prevalence of six-item ADL disability at only 3% among Nigerians aged 65 years and over(Oye Gureje, et al. 2006). The prevalence of disability among Nigerians is low because of the difference in criterion definition used. In the Ibadan Study of Aging, disability is based on difficulty experience with four levels of responses. This resulted in a more restrictive definition of disability, as compared to studies that defined disability based on

Many studies on the prevalence of physical disability were conducted in upper middle income countries. From the Survey on Health and Well-Being of Elders. Palloni *et al* reported that the prevalence of six-item ADL disability among older people were: 19% in Argentina, 14% in Barbados, 24% in Brazil, 26% in Chile, 21% in Cuba, 19% in Mexico and 17% in Uruguay (Palloni and McEniry 2007). The prevalence of six-item ADL disability among older people aged 60 years and over in Puerto Rico in a 2003 study was 20%(Palloni,

The epidemiology of poor physical function among older people in developing countries is

Several factors have been identified as risk factors for disability and functional limitation. These include non-modifiable risk factors (e.g. gender, ethnicity and genetics) and modifiable risk factors, which include both individual factors (such as sedentary lifestyle, unhealthy behaviours) as well as characteristics of the environment (e.g. household hazards,

Poor physical function had been reported to be associated with increasing age(Tas, et al. 2007a), being female(Tas, et al. 2007a), lower socioeconomic status(Tas, et al. 2007a), chronic diseases(Tas, et al. 2007a), depression (Tas, et al. 2007a), visual impairment(Ng, et al. 2006), cognitive impairment(Ng, et al. 2006), poor self rated health(Ng, et al. 2006), fewer social support(Tas, et al. 2007b), living alone(Ng, et al. 2006) and lack of exercise(Wu, et al. 1999). The association between female gender and poor physical function is consistently reported in many studies. Some studies have shown that the higher prevalence of poor physical function in female is unexplainable by known differences in sociodemographic and health

disadvantaged neighbourhood conditions, common forms of transportation).

**7.1 Gender, ethnic group, socioeconomic and health-related factors** 

related factors(Auxiliadora Graciani, et al. 2004; Dunlop, et al. 1997).

incompletely understood with many unanswered questions.

**7. Risk factors for poor physical function** 

any level of difficulty.

et al. 2005).

There are few reports of ethnic differences in frequency of poor physical function. How differences in sociodemographic and health-related factors explain the ethnic differences in poor physical function is still unclear. Older black and Hispanic Americans have a higher prevalence of poor physical function than their white counterparts (Kelly-Moore and Ferraro 2004). Other studies from the United States have found that African-American have higher disability rates compared to the Whites even after adjustment for education (Liao, et al. 1999) and chronic disease (Kingston and Smith 1997), although one study reported that social and health factors explained these differences(Kelly-Moore and Ferraro 2004). Ng *et al* showed that Indians and Malays in Singapore have higher risk of disability than Singaporean Chinese (Ng, et al. 2006).

Older people in less advantaged socioeconomic positions report more physical disability, mobility disability and functional limitation. Lower level of education tends to be associated with a higher prevalence of poor physical function at all ages(Lafortune 2007). A lower level of education is often associated with lower income, lower standards of living, higher risk of work-related injuries, and adoption of less healthy behaviours. The "education" effect has been shown to be a proxy for broader "socioeconomic status".

Changes in the prevalence of chronic diseases play a dominant role in explaining the prevalence of poor physical function among older people. However, not all diseases are associated with poor physical function and some are more strongly associated than others. Diseases with large effects on poor physical function include stroke and other neurological diseases, diabetes, heart diseases, depression, arthritis and other musculoskeletal diseases(Avlund 2004). It has also been reported that the presence of more than one chronic disease in an individual, often called co-morbidity is associated with poor physical function(Guralnik, et al. 1993; Schmitz, et al. 2007). Guralnik *et al* showed that the presence of a single chronic disease is a significant predictor of poor physical function, with the risk increasing incrementally up to the presence of four or more chronic diseases(Guralnik, et al. 1993).

There is also some evidence of association between smoking, heavy alcohol consumption and lack of physical activity with poor physical function(Tas, et al. 2007b).

The majority of studies on risk factors for poor physical function have focused on chronic diseases and lifestyle behaviours. There are a number of health-related factors that have rarely been investigated. These include the co-existence of depression and visual impairment; chronic pain; and the role of muscle strength, muscle mass (sarcopenia) and muscle quality.

#### **7.2 Co-existing depressive symptoms and visual impairment as risk factors of poor physical function**

The accumulation of deficits across more than one health domain, including physiological, sensory, cognitive and psychological domain, is likely to explain the development of poor physical function better than decline in just one single health domain. Whitson *et a*l showed that individuals with co-existing visual impairment and cognitive impairment are at high risk of disability(Whitson, et al. 2007). Lin *et al* showed that that the burden of having both vision and hearing impairment is greater than the sum of each single impairment(Lin, et al. 2004). Rantanen *at al* reported that the odds of severe mobility disability were ten times

Physical Function in Older People 23

Rantanen, et al. 2001). Perhaps because of the various operational definitions used, the relationship between age-related muscle mass (sarcopenia) and poor physical function has

In summary, poor physical function – physical disability, mobility disability and functional limitation is developing as the population ages. Poor physical functions are complex processes with multiple risk factors at work (Steven M Albert and Vicki A Freedman 2010). As such, multifactor interventions are needed to improve and maximize older people's physical functions. Identifying the appropriate target population and window of time for targeting an intervention is critical to its success. Furthermore, the issue of sustainability and adherence to these interventions are also important for long term success (Steven M Albert and Vicki A Freedman 2010). Research up to date is still incomplete in guiding public health practitioners and clinicians as to which interventions will improve and maximize older

This work was supported by the Fundamental Research Grant Scheme (FRGS), form the Ministry of Higher Education, Malaysia. Dr. Noran N Hairi's work was supported by the University Malaya / Ministry of Higher Education (UM/MOHE) High Impact Research

Anne B. Newman, et al. 2003 Strength and Muscle Quality in a Well-Functioning Cohort of

Auxiliadora Graciani, et al. 2004 Prevalence of disability and associated social and health-

Avlund, Kirsten 2004 Disability in old age. Longitudinal population-based studies of the

Berg, K. O., et al. 1992 Clinical and laboratory measures of postural balance in an elderly

Cesari, M., et al. 2005 Prognostic value of usual gait speed in well-functioning older people

Chen, P, ES Yu, and M Zhang 1995 ADL dependence and medical conditions in Chinese

Cress ME, Buchner DM, Questad KA, Esselman PC, deLateur BJ, Schwartz RS 1996

disablement process. Danish Medical Bulletin 51:315-349.

population. Arch Phys Med Rehabil 73(11):1073-80.

American Geriatrics Society 53(10):1675-80.

American Geriatrics Society 43:378 - 383.

Older Adults: The Health, Aging and Body Composition Study. Journal of the

related factors among the elderly in Spain: a population-based study. Maturitas

results from the Health, Aging and Body Composition Study. Journal of the

older persons: a population-based survey in Shanghai, China. Journal of the

Continous-scale physical functional performance in healthy older adults: a validation study. Archives of Physical Medicine and Rehabilitation 77:1243-1250.

not been consistent (I Janssen 2006; MJ. Delmonico, et al. 2007).

people's physical function in the long run.

American Geriatrics Society 51(3):323-330.

**9. Acknowledgements** 

Grant E000014-20001.

48(4):381-392.

**10. References** 

**8. Conclusion** 

greater among those who had both strength and balance impairments compared to those with just one or other impairment (Taina Rantanen, et al. 2001). Thus, it appears that certain pairs of co-existing conditions have a strong effect on physical function risk.

Depression and visual impairment are common conditions among older people and are also modifiable to a certain degree; depression can be treated and visual impairment can be corrected. However, it is unclear whether there is a synergistic effect of depressive symptoms (psychological health domain) and visual impairment (sensory domain) on the risk of poor physical function among older people.

#### **7.3 Chronic pain and poor physical function**

There are gender-based differences in mortality and morbidity; with men experiencing higher mortality rates and women generally having higher levels of morbidity (Steven M Albert and Vicki A Freedman 2010). In the pain literature, a robust and common finding is that women reported more pain, have lower pain thresholds and tolerance, and show different attitudes in coping with pain as compared to men (Roger, et al. 2009; Unruh 1996). Longitudinal and cross sectional population based studies have shown that the impact of pain goes beyond physical distress (Keogh, et al. 2006). The presence of pain is also associated with poor physical function (Duong, et al. 2005).

In contrast to gender differences in pain, the evidence about gender differences in pain outcomes, such as poor physical function, remains inconclusive. Cunningham *et al* found no difference in musculoskeletal pain related restriction in daily activities between genders(Cunningham and Kelsey 1984). The Health, Aging and Body Composition (ABC) Study also found no gender differences in the relationship between low back pain and physical function(Weiner, et al. 2003). However, studies that used pain-related disabilities items as an outcome found there were gender differences in reporting pain-related disabilities (Keefe, et al. 2000; Réthelyi, et al. 2001; Stubbs, et al. 2010).

#### **7.4 Sarcopenia as risk factors for poor physical function**

It is well established that the aging process in humans is associated with loss of muscle mass and strength (Doherty 2003; Y Rolland 2008 ). Age-related decline in muscle mass has been documented by lean body mass measurements with dual X-ray absorptiometry (DXA) and muscle cross sectional areas quantified by imaging methods such as X-ray computed tomography (CT) and magnetic resonance imaging (MRI). The age-related loss of muscle mass results from loss of both slow and fast motor units, with an accelerated loss of fast motor units. These changes in muscle morphology results in sharp age-related changes in muscle strength and muscle function(Lang, et al. 2010). Muscle quality is an indicator of muscle function, quantified by strength per unit muscle mass. Another morphological aspect of aging skeletal muscle is the infiltration of muscle tissue components by lipids. The aging process is thought to result in increased frequency of fat cells within muscle tissue(Anne B. Newman, et al. 2003).

Age-related loss of muscle mass, strength and quality is called "sarcopenia". Recent longitudinal studies have demonstrated that age-related loss of muscle strength increases the risk of poor physical function among older people (Giampaoli, et al. 1999; Taina Rantanen, et al. 2001). Perhaps because of the various operational definitions used, the relationship between age-related muscle mass (sarcopenia) and poor physical function has not been consistent (I Janssen 2006; MJ. Delmonico, et al. 2007).

#### **8. Conclusion**

22 Geriatrics

greater among those who had both strength and balance impairments compared to those with just one or other impairment (Taina Rantanen, et al. 2001). Thus, it appears that certain

Depression and visual impairment are common conditions among older people and are also modifiable to a certain degree; depression can be treated and visual impairment can be corrected. However, it is unclear whether there is a synergistic effect of depressive symptoms (psychological health domain) and visual impairment (sensory domain) on the

There are gender-based differences in mortality and morbidity; with men experiencing higher mortality rates and women generally having higher levels of morbidity (Steven M Albert and Vicki A Freedman 2010). In the pain literature, a robust and common finding is that women reported more pain, have lower pain thresholds and tolerance, and show different attitudes in coping with pain as compared to men (Roger, et al. 2009; Unruh 1996). Longitudinal and cross sectional population based studies have shown that the impact of pain goes beyond physical distress (Keogh, et al. 2006). The presence of pain is also

In contrast to gender differences in pain, the evidence about gender differences in pain outcomes, such as poor physical function, remains inconclusive. Cunningham *et al* found no difference in musculoskeletal pain related restriction in daily activities between genders(Cunningham and Kelsey 1984). The Health, Aging and Body Composition (ABC) Study also found no gender differences in the relationship between low back pain and physical function(Weiner, et al. 2003). However, studies that used pain-related disabilities items as an outcome found there were gender differences in reporting pain-related

It is well established that the aging process in humans is associated with loss of muscle mass and strength (Doherty 2003; Y Rolland 2008 ). Age-related decline in muscle mass has been documented by lean body mass measurements with dual X-ray absorptiometry (DXA) and muscle cross sectional areas quantified by imaging methods such as X-ray computed tomography (CT) and magnetic resonance imaging (MRI). The age-related loss of muscle mass results from loss of both slow and fast motor units, with an accelerated loss of fast motor units. These changes in muscle morphology results in sharp age-related changes in muscle strength and muscle function(Lang, et al. 2010). Muscle quality is an indicator of muscle function, quantified by strength per unit muscle mass. Another morphological aspect of aging skeletal muscle is the infiltration of muscle tissue components by lipids. The aging process is thought to result in increased frequency of fat cells within muscle

Age-related loss of muscle mass, strength and quality is called "sarcopenia". Recent longitudinal studies have demonstrated that age-related loss of muscle strength increases the risk of poor physical function among older people (Giampaoli, et al. 1999; Taina

pairs of co-existing conditions have a strong effect on physical function risk.

risk of poor physical function among older people.

associated with poor physical function (Duong, et al. 2005).

disabilities (Keefe, et al. 2000; Réthelyi, et al. 2001; Stubbs, et al. 2010).

**7.4 Sarcopenia as risk factors for poor physical function** 

tissue(Anne B. Newman, et al. 2003).

**7.3 Chronic pain and poor physical function** 

In summary, poor physical function – physical disability, mobility disability and functional limitation is developing as the population ages. Poor physical functions are complex processes with multiple risk factors at work (Steven M Albert and Vicki A Freedman 2010). As such, multifactor interventions are needed to improve and maximize older people's physical functions. Identifying the appropriate target population and window of time for targeting an intervention is critical to its success. Furthermore, the issue of sustainability and adherence to these interventions are also important for long term success (Steven M Albert and Vicki A Freedman 2010). Research up to date is still incomplete in guiding public health practitioners and clinicians as to which interventions will improve and maximize older people's physical function in the long run.

#### **9. Acknowledgements**

This work was supported by the Fundamental Research Grant Scheme (FRGS), form the Ministry of Higher Education, Malaysia. Dr. Noran N Hairi's work was supported by the University Malaya / Ministry of Higher Education (UM/MOHE) High Impact Research Grant E000014-20001.

#### **10. References**


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**Sarcopenia in Older People** 

*Faculty of Medicine, University of Malaya, Kuala Lumpur,* 

*Faculty of Medicine, University of Malaya, Kuala Lumpur, 3Institute for Public Health, National Institutes of Health,* 

*2JCUM, Centre for Clinical Epidemiology and Evidence-Based Medicine,* 

It is well established that the aging process is associated with numerous changes in the human body. One of the most significant age-related anatomical changes is that which happens to the skeletal muscle mass. Aging process is associated with loss of muscle mass and strength. The term "sarcopenia" is used to indicate progressive reduction in muscle mass, muscle strength and function that affects older people. Sarcopenia is derived from the Greek word "sarx" for flesh and "penia" for loss (M.S. John Pathy 2006). This term was first used by Rosenberg in 1988 at a symposium on nutritional status and body composition to bring awareness and draw attention to this significant but then understudied problem of aging (M.S. John Pathy 2006). Sarcopenia is now acknowledged as an important geriatric syndrome and is considered one of the hallmarks of aging process (Cruz-Jentoft, et al. 2010b). Research on the process, causes, consequences, management and treatment of agerelated muscle loss (mass, strength and quality) have exploded since the 1990's (Janssen

Sarcopenia results in unfavourable and detrimental effects on an older person's physical function. Muscle mass decrease is probably the single most frequent cause of late-life disability among older people. It is directly responsible for functional impairment with loss of strength, and increased likelihood of falls and fractures (Y Rolland 2008). As muscles account for 60% of the body protein stores, the reduction in lean body mass has other health effects independent of its functional consequences (Y Rolland 2008). A number of physiological functions that take place within the muscle tissues have an essential role in human metabolism. For example, muscles are important body protein reserves and energy that can be used in extreme conditions such as stress or malnutrition; amino-acids can be mobilised during acute infections and are also used as building blocks for antibodies while hormones are produced and catabolised within the muscle tissue (M.S. John Pathy 2006). In other words, reduction in muscle mass has an adverse impact on metabolic adaptation and

**1. Introduction** 

2010; Schranger M 2003).

Noran N. Hairi1,2, Awang Bulgiba1,2, Tee Guat Hiong3 and Izzuna Mudla4 *1Department of Social and Preventive Medicine,* 

> *Ministry of Health, 4Ministry of Health,*

> > *Malaysia*


### **Sarcopenia in Older People**

Noran N. Hairi1,2, Awang Bulgiba1,2,

Tee Guat Hiong3 and Izzuna Mudla4 *1Department of Social and Preventive Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, 2JCUM, Centre for Clinical Epidemiology and Evidence-Based Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, 3Institute for Public Health, National Institutes of Health, Ministry of Health, 4Ministry of Health, Malaysia* 

#### **1. Introduction**

28 Geriatrics

Yount, Kathryn M., and Emily M. Agree 2005 Differences in Disability among Older Women

Zhe, Tang, et al. 1999 The prevalence of functional disability in activities of daily living and

Zimmer, Zachary 2008 Poverty, wealth inequality and health among older adults in rural

instrumental activities of daily living among elderly Beijing Chinese. Archives of

and Men in Egypt and Tunisia. Demography 42:169-187.

Gerontology and Geriatrics 29(2):115-125.

Cambodia. Social Science & Medicine 66(1):57-71.

It is well established that the aging process is associated with numerous changes in the human body. One of the most significant age-related anatomical changes is that which happens to the skeletal muscle mass. Aging process is associated with loss of muscle mass and strength. The term "sarcopenia" is used to indicate progressive reduction in muscle mass, muscle strength and function that affects older people. Sarcopenia is derived from the Greek word "sarx" for flesh and "penia" for loss (M.S. John Pathy 2006). This term was first used by Rosenberg in 1988 at a symposium on nutritional status and body composition to bring awareness and draw attention to this significant but then understudied problem of aging (M.S. John Pathy 2006). Sarcopenia is now acknowledged as an important geriatric syndrome and is considered one of the hallmarks of aging process (Cruz-Jentoft, et al. 2010b). Research on the process, causes, consequences, management and treatment of agerelated muscle loss (mass, strength and quality) have exploded since the 1990's (Janssen 2010; Schranger M 2003).

Sarcopenia results in unfavourable and detrimental effects on an older person's physical function. Muscle mass decrease is probably the single most frequent cause of late-life disability among older people. It is directly responsible for functional impairment with loss of strength, and increased likelihood of falls and fractures (Y Rolland 2008). As muscles account for 60% of the body protein stores, the reduction in lean body mass has other health effects independent of its functional consequences (Y Rolland 2008). A number of physiological functions that take place within the muscle tissues have an essential role in human metabolism. For example, muscles are important body protein reserves and energy that can be used in extreme conditions such as stress or malnutrition; amino-acids can be mobilised during acute infections and are also used as building blocks for antibodies while hormones are produced and catabolised within the muscle tissue (M.S. John Pathy 2006). In other words, reduction in muscle mass has an adverse impact on metabolic adaptation and

Sarcopenia in Older People 31

(Cruz-Jentoft, et al. 2010a). The EWGSOP included representatives from four participant organisations i.e. the European Union Geriatric Medicine Society (EUGMS), the European Society for Clinical Nutrition and Metabolism (ESPEN), the International Associations of Gerontology and Geriatrics -European Region (IAGG-ER) and the International Association of Nutrition and Aging (Valderrama-Gama, et al.). The EWGSOP recommends using the presence of both low muscle mass and low muscle function (strength or performance) for the diagnosis of sarcopenia (Cruz-Jentoft, et al. 2010a). The diagnosis requires the presence

of criterion 1 and the presence of either criterion 2 or 3 (see Table 1).

2010a).

1. Low muscle mass 2. Low muscle strength 3. Low physical performance

Ageing, 2010: 39: 412-423.

Table 1. Criteria for the diagnosis of sarcopenia

**2.1 Measuring sarcopenia – The quantitative approach** 

Diagnosis is based on documentation of criterion 1 plus (criterion 2 or criterion 3)

Source: Report of the EWGSOP. Sarcopenia: European consensus on definition and diagnosis. Age and

The EWGSOP report argues that the rationale in using two criteria is that muscle strength does not depend solely on muscle mass and the relationship between strength and mass is not linear (Cruz-Jentoft, et al. 2010a). Furthermore, defining sarcopenia in terms of muscle mass alone is too narrow and may be of limited clinical value. The EWGSOP report also categorised sarcopenia into three staging that reflects the severity of the condition: - a presarcopenia stage (characterised by low muscle mass without impact on muscle strength or physical performance), sarcopenia stage (characterised by low muscle mass and low muscle strength or low physical performance) and severe sarcopenia (characterised by low muscle mass, low muscle strength and low physical performance) (Cruz-Jentoft, et al.

The measurement variables include muscle mass, strength and physical performance. Agerelated decline in muscle mass has been documented by lean body mass measurements with dual X-ray absorptiometry (DXA), muscle cross sectional areas quantified by bioimaging methods such as X-ray computed tomography (CT) and magnetic resonance imaging (MRI), estimation of the volume of fat and lean body mass using bioimpedance analysis (BIA) and finally anthropometric measurements (i.e. calculations based on mid-upper arm circumference and skin-fold thickness) (M.S. John Pathy 2006). DXA is a better method for measuring muscle mass than bioelectric impedance and anthropometric measurements. DXA has the advantage of providing precise estimates of skeletal lean mass and being noninvasive compared to other accurate laboratory-based methods such as neutron activation and 40K counting (M.S. John Pathy 2006). However, DXA is not portable and cannot be used in large-scale epidemiological studies. BIA may be considered as a portable alternative to DXA (Cruz-Jentoft, et al. 2010a). Muscle strength can be measured using isometric hand

immunological response to disease. Nevertheless, there remains considerable unexplained variation in muscle mass and strength among older people which may partly be explained by the observation that muscle mass and strength in later life reflect not only the rate of loss but also the peak attained earlier in life (A A Sayer 2008; M.S. John Pathy 2006). Thus, a life course model of sarcopenia will enable us to understand sarcopenia, its influences and develop effective interventions (A A Sayer 2008). This is shown in Figure 1.

Fig. 1. A life course model of sarcopenia.

Taking all these into account, sarcopenia is now one of the main focal points in aging research; drawing attention to its epidemiology, causes, consequences as well as health care costs. Increasing awareness of sarcopenia and promoting health enhancing strategies to overcome sarcopenia offers numerous benefits. This chapter provides an overview of the current literature on sarcopenia in older people.

#### **2. Definition of sarcopenia**

Sarcopenia is now defined as a geriatric syndrome characterised by progressive and generalised loss of skeletal muscle mass, strength and quality associated with ageing (Cruz-Jentoft, et al. 2010b). Sarcopenia is also associated with multiple contributing risk factors through a common and complex path, with a risk of adverse outcomes such as increased frailty and physical and mobility disability leading to loss of dependence, poor quality of life, increased healthcare costs and ultimately death (Cruz-Jentoft, et al. 2010b; M.S. John Pathy 2006; Y Rolland 2008 ).

Despite agreement in the conceptual definition of sarcopenia, the consensus on the operational definition of sarcopenia has yet to be reached. The definition of sarcopenia has been thoroughly discussed and the pooled consensus is that sarcopenia is mainly, but not only an age-related condition defined by the combined presence of reduced muscle mass and muscle function (Cruz-Jentoft, et al. 2010a; Muscaritoli, et al. 2010).

The European Working Group on Sarcopenia in Older People (EWGSOP) developed a practical clinical definition and consensus diagnostic criteria for age-related sarcopenia

immunological response to disease. Nevertheless, there remains considerable unexplained variation in muscle mass and strength among older people which may partly be explained by the observation that muscle mass and strength in later life reflect not only the rate of loss but also the peak attained earlier in life (A A Sayer 2008; M.S. John Pathy 2006). Thus, a life course model of sarcopenia will enable us to understand sarcopenia, its influences and

Taking all these into account, sarcopenia is now one of the main focal points in aging research; drawing attention to its epidemiology, causes, consequences as well as health care costs. Increasing awareness of sarcopenia and promoting health enhancing strategies to overcome sarcopenia offers numerous benefits. This chapter provides an overview of the

Sarcopenia is now defined as a geriatric syndrome characterised by progressive and generalised loss of skeletal muscle mass, strength and quality associated with ageing (Cruz-Jentoft, et al. 2010b). Sarcopenia is also associated with multiple contributing risk factors through a common and complex path, with a risk of adverse outcomes such as increased frailty and physical and mobility disability leading to loss of dependence, poor quality of life, increased healthcare costs and ultimately death (Cruz-Jentoft, et al. 2010b; M.S. John

Despite agreement in the conceptual definition of sarcopenia, the consensus on the operational definition of sarcopenia has yet to be reached. The definition of sarcopenia has been thoroughly discussed and the pooled consensus is that sarcopenia is mainly, but not only an age-related condition defined by the combined presence of reduced muscle mass

The European Working Group on Sarcopenia in Older People (EWGSOP) developed a practical clinical definition and consensus diagnostic criteria for age-related sarcopenia

and muscle function (Cruz-Jentoft, et al. 2010a; Muscaritoli, et al. 2010).

develop effective interventions (A A Sayer 2008). This is shown in Figure 1.

Age

current literature on sarcopenia in older people.

Fig. 1. A life course model of sarcopenia.

**2. Definition of sarcopenia** 

Pathy 2006; Y Rolland 2008 ).

(Cruz-Jentoft, et al. 2010a). The EWGSOP included representatives from four participant organisations i.e. the European Union Geriatric Medicine Society (EUGMS), the European Society for Clinical Nutrition and Metabolism (ESPEN), the International Associations of Gerontology and Geriatrics -European Region (IAGG-ER) and the International Association of Nutrition and Aging (Valderrama-Gama, et al.). The EWGSOP recommends using the presence of both low muscle mass and low muscle function (strength or performance) for the diagnosis of sarcopenia (Cruz-Jentoft, et al. 2010a). The diagnosis requires the presence of criterion 1 and the presence of either criterion 2 or 3 (see Table 1).

Diagnosis is based on documentation of criterion 1 plus (criterion 2 or criterion 3)

1. Low muscle mass


Source: Report of the EWGSOP. Sarcopenia: European consensus on definition and diagnosis. Age and Ageing, 2010: 39: 412-423.

Table 1. Criteria for the diagnosis of sarcopenia

The EWGSOP report argues that the rationale in using two criteria is that muscle strength does not depend solely on muscle mass and the relationship between strength and mass is not linear (Cruz-Jentoft, et al. 2010a). Furthermore, defining sarcopenia in terms of muscle mass alone is too narrow and may be of limited clinical value. The EWGSOP report also categorised sarcopenia into three staging that reflects the severity of the condition: - a presarcopenia stage (characterised by low muscle mass without impact on muscle strength or physical performance), sarcopenia stage (characterised by low muscle mass and low muscle strength or low physical performance) and severe sarcopenia (characterised by low muscle mass, low muscle strength and low physical performance) (Cruz-Jentoft, et al. 2010a).

#### **2.1 Measuring sarcopenia – The quantitative approach**

The measurement variables include muscle mass, strength and physical performance. Agerelated decline in muscle mass has been documented by lean body mass measurements with dual X-ray absorptiometry (DXA), muscle cross sectional areas quantified by bioimaging methods such as X-ray computed tomography (CT) and magnetic resonance imaging (MRI), estimation of the volume of fat and lean body mass using bioimpedance analysis (BIA) and finally anthropometric measurements (i.e. calculations based on mid-upper arm circumference and skin-fold thickness) (M.S. John Pathy 2006). DXA is a better method for measuring muscle mass than bioelectric impedance and anthropometric measurements. DXA has the advantage of providing precise estimates of skeletal lean mass and being noninvasive compared to other accurate laboratory-based methods such as neutron activation and 40K counting (M.S. John Pathy 2006). However, DXA is not portable and cannot be used in large-scale epidemiological studies. BIA may be considered as a portable alternative to DXA (Cruz-Jentoft, et al. 2010a). Muscle strength can be measured using isometric hand

Sarcopenia in Older People 33

*Increase muscle turnover*  ↑Catabolic stimuli ↑ Protein degradation Low grade inflammation ↓Anabolic stimuli ↓Protein synthesis

*Reduced number of muscle cells*  ↑Myostatin (↓ recruitment) ↑ Apoptosis

*Hormonal deregulation*  ↓ Testosterone, DHEA production ↓Oestrogen production ↓ 1-25 (OH)2 vitamin D ↑ Thyroid Function ↓ Growth hormone, IGF-1 ↑ Insulin resistance

*Changes in neuromuscular system* ↓ CNS input (loss of α- motor neurons) Neuromuscular disjunction ↓ Cilliary neurotrophic factor ↓ Motor unit firing rate

*Mitochondrial dysfunction*  ↓ Peripheral vascular flow Source: Cruz-Jentoft AJ, Landi F, Topinkova E *et al*. Understanding sarcopenia as a geriatric syndrome.

Age-related loss of muscle mass and strength result in decreased functional limitation and physical disability among older people. Using the Nagi Model of Disablement pathology (e.g. sarcopenia) first leads to impairment such as lower extremity weakness (Steven M Albert and Vicki A Freedman 2010). When this crosses some threshold, functional impairment begins to show (which is measurable via gait speed below age-sex appropriate norm) and this in turn will lead to physical disability, e.g. needing help to cross the street

(Steven M Albert and Vicki A Freedman 2010). This is as shown in Figure 3.

Current Opinion in Clinical Nutrition and Metabolic Care. 2010; 13: 1-7

**4. Functional consequences of sarcopenia** 

*Constitutional*  Female Low birth weight Genetic susceptibility

*Lifestyle*  Malnutrition Low protein intake Alcohol abuse Smoking Physical inactivity

*Living conditions*  Starvation Bed rest Immobility deconditioning Weightlessness

Table 2. Risk factors of sarcopenia

**FACTORS AGING PROCESS CHRONIC HEALTH** 

**CONDITIONS** 

Cognitive impairment Mood disturbances Diabetes Mellitus Heart Failure Liver Failure Renal Failure Respiratory Failure Osteoarthritis Chronic Pain

Obesity Catabolic effects of drugs

Cancer ? Chronic inflammatory Disease?

grip. Muscle strength alone has been shown to be the most useful indicator of age-related changes in muscle for use in clinical practice (Hairi NN 2010). Grip strength is a good simple measure of muscle strength and correlates with leg strength (Cruz-Jentoft, et al. 2010a). Other measures of muscle strength include knee flexion /extension and peak expiratory flow (PEF) (Cruz-Jentoft, et al. 2010a). With regards to physical performance, a wide range of tests are available including Tinetti Performance Oriented Mobility Test, Gait Speed, Functional Independence Measure and the Timed Get-Up-and-Go (TGUG) test (Guralnik and Luigi 2003). Cut-off points depend upon the measurement technique chosen and on the availability of reference studies. The EWGSOP recommends the use of normative (healthy young adult) rather than other predictive reference populations (Cruz-Jentoft, et al. 2010a).

To date, sarcopenia has not been included in common classifications of disease (i.e. International Classification of Diseases), although some recent initiatives are trying to move in this direction.

#### **3. Aetiology and pathogenesis of sarcopenia**

The aetiology of sarcopenia is multifactorial (Cruz-Jentoft, et al. 2010b; Lang, et al. 2010; Y Rolland 2008 ). Multiple risk factors contribute to the development and progression of sarcopenia. These risk factors can be grouped into several categories such as constitutional factors, the aging process, certain life habits such as decreased protein intake, disuse or poor physical activity including lack of exercise, the use of tobacco and alcohol intake, changes in living conditions such as prolonged bed rest and immobility and chronic health conditions (Cruz-Jentoft, et al. 2010b). Table 2 shows the risk factors of sarcopenia.

The pathogenesis of sarcopenia is part of a complex process of age-related changes in musculoskeletal cellular as well as tissue structure and function (Doherty 2003; Lang, et al. 2010). Social and lifestyle behaviours such as physical inactivity, smoking, poor diet, being obese, as well as age-related hormonal, neurological, immunological and metabolic factors are important risk factors (M.S. John Pathy 2006). Genetic susceptibility also plays a role in sarcopenia formation(Muscaritoli, et al. 2010). The putative causes of sarcopenia have been catergorised into "intrinsic" and "extrinsic" factors (M.S. John Pathy 2006; Muscaritoli, et al. 2010). Reductions in anabolic hormones (testosterone, estrogens, growth hormones, insulin like growth factor-1), increases of apoptotic activities in the myofibers, increases of proinflammatory cytokines (e.g. TNF-α, IL-6), oxidative stress due to accumulation of free radicals, changes of the mitochondrial function of muscle cells and a decline in the number of α-motoneurons are some of the intrinsic factors involved (Lang, et al. 2010; Muscaritoli, et al. 2010). Deficient intake of energy and protein, reduced intake of vitamin D, acute and chronic co-morbidities and reduced physical activity are some of the extrinsic conditions leading to sarcopenia (Cruz-Jentoft, et al. 2010b; Muscaritoli, et al. 2010). Figure 2 shows the factors contributing to sarcopenia and its consequences.

What is not known is which factors or pathways are relatively more or less important with regards to the severity and rate of development of sarcopenia components; muscle mass, strength and quality. Each factor potentially contributes differently to the loss of muscle mass, strength and quality and it is likely that there is considerable individual variability in the interactions of these factors (M.S. John Pathy 2006).

grip. Muscle strength alone has been shown to be the most useful indicator of age-related changes in muscle for use in clinical practice (Hairi NN 2010). Grip strength is a good simple measure of muscle strength and correlates with leg strength (Cruz-Jentoft, et al. 2010a). Other measures of muscle strength include knee flexion /extension and peak expiratory flow (PEF) (Cruz-Jentoft, et al. 2010a). With regards to physical performance, a wide range of tests are available including Tinetti Performance Oriented Mobility Test, Gait Speed, Functional Independence Measure and the Timed Get-Up-and-Go (TGUG) test (Guralnik and Luigi 2003). Cut-off points depend upon the measurement technique chosen and on the availability of reference studies. The EWGSOP recommends the use of normative (healthy young adult) rather than other predictive reference populations (Cruz-Jentoft, et al. 2010a). To date, sarcopenia has not been included in common classifications of disease (i.e. International Classification of Diseases), although some recent initiatives are trying to move

The aetiology of sarcopenia is multifactorial (Cruz-Jentoft, et al. 2010b; Lang, et al. 2010; Y Rolland 2008 ). Multiple risk factors contribute to the development and progression of sarcopenia. These risk factors can be grouped into several categories such as constitutional factors, the aging process, certain life habits such as decreased protein intake, disuse or poor physical activity including lack of exercise, the use of tobacco and alcohol intake, changes in living conditions such as prolonged bed rest and immobility and chronic health conditions

The pathogenesis of sarcopenia is part of a complex process of age-related changes in musculoskeletal cellular as well as tissue structure and function (Doherty 2003; Lang, et al. 2010). Social and lifestyle behaviours such as physical inactivity, smoking, poor diet, being obese, as well as age-related hormonal, neurological, immunological and metabolic factors are important risk factors (M.S. John Pathy 2006). Genetic susceptibility also plays a role in sarcopenia formation(Muscaritoli, et al. 2010). The putative causes of sarcopenia have been catergorised into "intrinsic" and "extrinsic" factors (M.S. John Pathy 2006; Muscaritoli, et al. 2010). Reductions in anabolic hormones (testosterone, estrogens, growth hormones, insulin like growth factor-1), increases of apoptotic activities in the myofibers, increases of proinflammatory cytokines (e.g. TNF-α, IL-6), oxidative stress due to accumulation of free radicals, changes of the mitochondrial function of muscle cells and a decline in the number of α-motoneurons are some of the intrinsic factors involved (Lang, et al. 2010; Muscaritoli, et al. 2010). Deficient intake of energy and protein, reduced intake of vitamin D, acute and chronic co-morbidities and reduced physical activity are some of the extrinsic conditions leading to sarcopenia (Cruz-Jentoft, et al. 2010b; Muscaritoli, et al. 2010). Figure 2 shows the

What is not known is which factors or pathways are relatively more or less important with regards to the severity and rate of development of sarcopenia components; muscle mass, strength and quality. Each factor potentially contributes differently to the loss of muscle mass, strength and quality and it is likely that there is considerable individual variability in

in this direction.

**3. Aetiology and pathogenesis of sarcopenia** 

factors contributing to sarcopenia and its consequences.

the interactions of these factors (M.S. John Pathy 2006).

(Cruz-Jentoft, et al. 2010b). Table 2 shows the risk factors of sarcopenia.


Source: Cruz-Jentoft AJ, Landi F, Topinkova E *et al*. Understanding sarcopenia as a geriatric syndrome. Current Opinion in Clinical Nutrition and Metabolic Care. 2010; 13: 1-7

Table 2. Risk factors of sarcopenia

#### **4. Functional consequences of sarcopenia**

Age-related loss of muscle mass and strength result in decreased functional limitation and physical disability among older people. Using the Nagi Model of Disablement pathology (e.g. sarcopenia) first leads to impairment such as lower extremity weakness (Steven M Albert and Vicki A Freedman 2010). When this crosses some threshold, functional impairment begins to show (which is measurable via gait speed below age-sex appropriate norm) and this in turn will lead to physical disability, e.g. needing help to cross the street (Steven M Albert and Vicki A Freedman 2010). This is as shown in Figure 3.

Sarcopenia in Older People 35

**Physical disability (ADL)** 

Grip strength§ 2.83 (1.91, 4.20) 1.79 (1.17, 2.74) 1.09 (0.72, 1.65) Quadriceps strength§ 4.48 (2.43, 8.27) 3.24 (1.68, 6.23) 2.07 (1.14, 3.78)

aLM/height + 1.89 (1.25, 2.86) 1.29 (0.84, 1.99) 1.41 (0.88, 2.26) aLM/fat mass<sup>≠</sup> 2.99 (2.05, 4.38) 2.79 (1.93, 4.05) 2.08 (1.37, 3.15) residuals 2.95 (2.00, 4.36) 2.18 (1.43, 3.32) 1.75 (1.10, 2.78)

specific force §, ¶ 1.95 (1.26, 3.03) 1.63 (1.07, 2.49) 1.19 (0.77, 1.85)

specific force §, # 3.38 (1.82, 6.30) 2.71 (1.44, 5.08) 2.01 (1.05, 3.83) \*Adjusted for country of birth, age group, education level, PASE score, co-morbidity, stroke, arthritis,

Source: Hairi NN, Cumming R, Naganathan V *et al.* Loss of Muscle Strength, Mass (Sarcopenia), and Quality (Specific Force) and Its Relationship with Functional Limitation and Physical Disability: The Concord Health and Ageing in Men Project. Journal of the American Geriatrics Society. 2010: 58: 2055-2062 Table 3. Prevalence ratios for low muscle strength, muscle mass and muscle quality and

The relationship between age-related muscle changes and poor physical function is complex. Muhlberg and Siber described three possible "vicious loops" that involve feedback from physiological and behavioural systems. The "vicious loops" are the immobilization loop, the nutritional loop and the metabolic loop (M.S. John Pathy 2006). The vicious loop between sarcopenia and immobilization is described as: sarcopenia → neuromuscular impairment → falls and fractures → immobilization → sarcopenia. The second loop is the "nutritional" vicious loop between sarcopenia and malnutrition: sarcopenia → immobilization → decline of nutrition skills (empty refrigerator) → malnutrition impaired protein synthesis → sarcopenia. Finally, the "metabolic" vicious loop between sarcopenia and the decline of protein reserve in the body: sarcopenia → decline of protein reserve of the body → diminished capacity to meet the extra demand of protein synthesis associated

As sarcopenia (loss of muscle strength, muscle mass and quality) was found to be associated with poor physical function, improvements in muscle strength would prevent

Upper extremity

Lower extremity

+Additionally adjusted for obesity. ≠Additionally adjusted for height. § Additionally adjusted for pain.

physical disability, CHAMP Study.

disease and injury → sarcopenia.

**5. Prevention and treatments for sarcopenia** 

ǁ Ratio of grip strength (measured in kg of force) to arm lean mass
