The Challenge of Understanding Sarcopenia, Muscle Strength and

Disability

Jack M. Guralnik, M.D., Ph.D.

Department of Epidemiology and Public Health

University of Maryland School of Medicine

Domains of Functioning• Physical• Cognitive• Psychological• Sensory• Social

Disability

• Expression of a physical or mental limitation in a social context

• The gap between a person’s capabilities and the demands of the environment

IOM, 1991

Disability Domains• Self-care: ADLs

• Independence living in the community: IADLs

• Mobility (ambulation) at home and in the community: Mobility disability

Activities of Daily Living: ADLsBasic Self-Care Tasks• Eating• Dressing• Bathing• Transferring from bed to chair• Using the toilet

Instrumental Activities of Daily Living: IADLS

• Preparing meals• Shopping• Housekeeping• Managing money• Taking medications• Using the telephone

Prevalence of Difficulty Walking ¼ Mile, NHIS, 1998

Per

cent

Men Women

29.437.5

45.0

57.0

70.280.1

0

20

40

60

80

65-74 75-84 85+ 65-74 75-84 85+

Ability to move through one’s environment without assistance

Efficient and reliable locomotion is a fundamental feature of human functioning, and indeed functioning across virtually all animal species

Mobility

Proportion of Persons with Catastrophic and ProgressiveDisability Among Those Who Developed Severe Disability

CatastrophicdisabilityProgressivedisability

Pro

porti

on o

f the

sev

erel

y di

sabl

ed

100

80

60

40

20

0

Source: Ferrucci et al. J Gerontol Med Sci 1996;51A:M123-M130.

Age (years)

69-74 75-79 80-84 85+

M M M M WWWW

Disability

Demographics

Behavioral risk factors

Disease

DisabilityFunctional Limitations

Restrictions in basic physical and mental

actions (ambulate, reach, grasp, climb stairs, speak,

see standard print)

Impairments

Dysfunction and structural abnormalities in specific body

systems (musculoskeletal, cardiovascular, etc.)

Demographics

Behavioral risk factors

Disease

Theoretical Model of the Pathway from Disease to Disability: Nagi

Mean Grip Strength in Nonsurvivors and Survivors at Baseline and Survivors at Follow-up 27 Years Later

Honolulu Heart Program and Honolulu Asia Aging Study

Source: Rantanen et al. J Appl Physiol 1998;85:2047

Mortality Rates in Groups Based on BMI and Hand Grip Strength

Honolulu-Asia Aging Study

Source: Rantanen et al. J Gerontol Med Sci 2000;55:M168-73.

Proportion of Subjects with Functional Limitations in1991-93 According to Grip Strength Tertiles

25 Years Earlier

HighestMiddleLowest

Grip Strength Tertiles

Percent

Unable to Rise from a Chair

Walking Speed 0.4 m/s

Functional Limitations

(3,218 Initially Healthy 45- to 68-year-old Men, HAAS)

Source: Rantanen et al. JAMA 1999;281:558-560.

0 5 10 15 20 25 30

Proportion of Subjects with Disability in 1991-93 Accordingto Grip Strength Tertiles 25 Years Earlier

HighestMiddleLowest

Grip Strength Tertiles

Doing HeavyHousehold Work

Self-reported Difficulty

Percent

(3,218 Initially Healthy 45- to 68-year-old Men, Honolulu)

Source: Rantanen et al., JAMA 1999;281:558-560.

Toileting

Dressing

Walking Up 10 Step

Walking 1/2 mile

0 5 10 15 20 25 30

Sarcopenia• The age-related loss in skeletal muscle

• Sarx = flesh, penia = poverty– IR Rosenberg. Am J Clin Nutr 1989;50(suppl):1231-3– WJ Evans & WW Campbell. J Nutr 1993;123:465-8

The Sarcopenia Hypothesis• Muscle mass is lost progressively after

mid-adulthood• Muscle mass correlates with strength• Low strength is a hallmark of disability• Many disabling conditions are

associated with accelerated loss of lean mass

Age-related changes in body composition

Age 63 Age 79

John Turner – Weight Lifter

Mid-Femur CT Images from the BLSA (all women with BMI 30-32)

Age=80 Years

Age=55 Years

Age=33 Years

Dual Energy X-ray Absorptiometry (DEXA)

Skeletal muscle mass and distribution in 468 men and women aged 18–88 yrIAN JANSSEN, STEVEN B. HEYMSFIELD, ZIMIAN WANG, and ROBERT ROSS

J Appl Physiol 89:81-88, 2000

Men

Women

The Effect of Bed Rest on Muscle

• Over 2 pounds of muscle in the legs (6.3% decline)

• More than 15% of lower extremity strength

After 10 days of bed rest, healthy older adults lost…

Kortebein et al. JAMA 2007;297:1772-4.

25-34 35-44 45-54 55-64 65-74 75-84 85+

-40%

-35%

-30%

-25%

-20%

-15%

-10%

-5%

0%

5%

Knee Strength

Leg Muscle Mass

Perc

ent C

hang

e

Longitudinal Percent Change in Muscle Strengthby Decade 25-98 yrs.

The Baltimore Longitudinal Study of Aging

Annualized declines in leg lean mass (hatched bar) and muscle strength (black bar) in the Health ABC Study.

Goodpaster BH et al. The Loss of Skeletal Muscle Strength, Mass, and Quality in Older Adults: The Health, Aging and Body Composition Study. J Gerontol A Biol Sci Med Sci. 2006;61:M1059-M1064.

Hazard Ratios for Incident Mobility Limitations by Quartiles of Three Muscle Parameters: Health ABC - WOMEN

Adjusted for: age, race, site, height, total fat mass, education, alcohol, smoking statusphysical activity, prevalent disease, self-rated health, depression, cognition and other parameters.

Visser et al, J Gerontol A Biol Sci Med Sci. 2005 Mar;60(3):324-33

0

0.5

1

1.5

2

2.5

Area Attenuation Strength

Adju

sted

HR

Muscle Mass and Muscle Strength are Not Equivalent

• Interventions that increase lean mass don’t necessarily increase strength (e.g. GH).

• Strength increases seen with resistance training precede and are far in excess of measurable changes in muscle mass.

• Voluntary weight loss leads to losses in skeletal mass but not changes in strength.

• Therefore, muscle mass alone is not adequate for characterizing or diagnosing sarcopenia.

European Working Group on Sarcopenia in Older People1

Low Muscle Mass and

Low Muscle Strength orLow Physical Performance

1. Cruz-Jentoft AJ et al. Age and Ageing 2010;39:412-4232. Muscaritoli M et al Clinical Nutrition 2010;29:154-159

ESPEN’s Cachexia-Anorexia & Nutrition in Geriatrics SIGs2

% muscle mass ≥ 2 sd below young adults matched on sex and ethnicity, and

Low gait speed (e.g. < 0.8 m/s over 4 meters)

New Composite Definitions

“See, the problem with doing things to prolong your life is that all the extra years come at the end, when you’re old.”