The loss of skeletal muscle strength, mass, and quality in older adults: the health, aging and body composition study.

Background: The loss of muscle mass is considered to be a major determinant of strength loss in aging. However, large-scale longitudinal studies examining the association between the loss of mass and strength in older adults are lacking.

Methods: Three-year changes in muscle mass and strength were determined in 1880 older adults in the Health, Aging and Body Composition Study.

Diabetes, inflammation, and functional decline in older adults: findings from the Health, Aging and Body Composition (ABC) study.

Objective: Age, diabetes, and elevated inflammatory markers independently increase the risk of functional decline. We examined the effect of C-reactive protein (CRP) and interleukin-6 (IL-6) on the incident mobility limitation in older adults with and without diabetes.

Research Design And Methods: We analyzed data from a cohort of 2,895 well-functioning adults aged 70-79 years, followed for development of persistent functional limitation over 3.

Assessment of intramuscular triglycerides: contribution to metabolic abnormalities.

Purpose Of Review: The purpose of this review is to highlight recent methodological advances that have helped us to understand the role of intramuscular triglycerides in human health as well as prevention and treatment of disease. In addition to both invasive (muscle biopsy) and noninvasive methods, techniques to assess other lipids within muscle will be reviewed.

Recent Findings: In addition to intramuscular triglycerides, other lipids contained within skeletal muscle such as diacylglycerol and ceramides may have an important role in human metabolic disease.

Daily activity energy expenditure and mortality among older adults.

Context: Exercise is associated with mortality benefits but simply expending energy through any activity in an individual's free-living environment may confer survival advantages.

Objective: To determine whether free-living activity energy expenditure is associated with all-cause mortality among older adults.

Design, Setting, And Participants: Free-living activity energy expenditure was assessed in 302 high-functioning, community-dwelling older adults (aged 70-82 years).

Effects of exercise on mitochondrial content and function in aging human skeletal muscle.

Skeletal muscle mitochondria are implicated with age-related loss of function and insulin resistance. We examined the effects of exercise on skeletal muscle mitochondria in older (age = 67.3 +/- 0.

Decreased muscle strength and quality in older adults with type 2 diabetes: the health, aging, and body composition study.

Adequate skeletal muscle strength is essential for physical functioning and low muscle strength is a predictor of physical limitations. Older adults with diabetes have a two- to threefold increased risk of physical disability. However, muscle strength has never been investigated with regard to diabetes in a population-based study.

Metabolic syndrome and the risk of cardiovascular disease in older adults.

Objectives: The purpose of this study was to assess whether metabolic syndrome (MetSyn) predicts a higher risk for cardiovascular events in older adults.

Background: The importance of MetSyn as a risk factor has not previously focused on older adults and deserves further study.

Methods: We studied the impact of MetSyn (38% prevalence) on outcomes in 3,035 participants in the Health, Aging, and Body Composition (Health ABC) study (51% women, 42% black, ages 70 to 79 years).

Adipocytokines and incident diabetes mellitus in older adults: the independent effect of plasminogen activator inhibitor 1.

Background: Adipose tissue produces "adipocytokines" of uncertain clinical significance.

Methods: We analyzed the relationships among adiposity, adipocytokines, glycemia, and incident diabetes mellitus in 2356 white and black adults aged 70 to 79 years in the Health, Aging, and Body Composition Study who did not have diabetes at baseline. We measured the levels of adipocytokines adiponectin, leptin, interleukin 6, tumor necrosis factor alpha, and plasminogen activator inhibitor 1.

Strength, but not muscle mass, is associated with mortality in the health, aging and body composition study cohort.

Background: Although muscle strength and mass are highly correlated, the relationship between direct measures of low muscle mass (sarcopenia) and strength in association with mortality has not been examined.

Methods: Total mortality rates were examined in the Health, Aging and Body Composition (Health ABC) Study in 2292 participants (aged 70-79 years, 51.6% women, and 38.

Estrogen replacement, muscle composition, and physical function: The Health ABC Study.

Purpose: Although the beneficial effects of estrogen use on cardiovascular and cognitive function in postmenopausal women have been recently discredited, controversy remains regarding its usefulness for maintaining skeletal muscle mass or strength. Therefore, the purpose of this study was to determine whether estrogen use is associated with enhanced muscle composition and, if so, whether this translates into improved strength and physical function.

Methods: Cross-sectional analysis of 840 well-functioning community-dwelling white women (current estrogen replacement therapy (ERT) users = 259, nonusers = 581) aged 70-79 yr participating in the Health, Aging and Body Composition Study.

Weight change and the conservation of lean mass in old age: the Health, Aging and Body Composition Study.

Background: Weight loss may contribute to the loss of lean mass with age.

Objective: The objective was to evaluate the relation between weight loss or weight gain and changes in lean mass and fat mass in older adults.

Design: We observed changes in weight and body composition during a 4-y period in 2163 men (47%) and women (53%) aged 70-79 y in the Health, Aging and Body Composition Study cohort.

Increased intramuscular lipid storage in the insulin-resistant and endurance-trained state.

Numerous studies have reported a strong correlation between intramuscular triacylglycerol (IMTG) content and insulin resistance. However, the proposed relationship between IMTG accumulation and skeletal muscle insulin resistance is not unambiguous, as trained athletes have been shown to be markedly insulin sensitive despite an elevated IMTG storage. Though the latter has often been attributed to differences in muscle fibre type composition and/or structural characteristics of the intramyocellular lipid deposits, recent studies have failed to provide such evidence.

Lower serum albumin concentration and change in muscle mass: the Health, Aging and Body Composition Study.

Background: Low albumin concentrations in older persons increase the risk of poor health outcomes, including functional decline.

Objective: The aim of the study was to investigate the association between serum albumin concentration and skeletal muscle loss (sarcopenia) in old age.

Design: Serum albumin concentration was measured in 1882 black and white men and women aged 70-79 y participating in the Health, Aging and Body Composition Study.

Angiotensin-converting enzyme insertion/deletion genotype, exercise, and physical decline.

Context: Physical performance in response to exercise appears to be influenced by the angiotensin-converting enzyme (ACE) insertion (I)/deletion (D) genotype in young adults, but whether this relationship could help explain variation in older individuals' response to exercise has not been well studied.

Objective: To determine whether the ACE genotype interacts with significant physical activity to affect the incidence of mobility limitation in well-functioning older adults.

Design, Setting, And Participants: The Health Aging and Body Composition (Health ABC) Cohort Study, conducted in the metropolitan areas of Memphis, Tenn, and Pittsburgh, Pa.

Skeletal muscle lipid and its association with insulin resistance: what is the role for exercise?

Skeletal muscle lipid content has been associated with insulin resistance and type 2 diabetes. However, intramuscular triglycerides can also be a fuel source for healthy muscle during exercise. The balance between storage and use of muscle triglycerides is likely a key to the interaction between dysregulated fat and glucose metabolism by healthy and insulin resistant muscle.

Muscle mass, muscle strength, and muscle fat infiltration as predictors of incident mobility limitations in well-functioning older persons.

Background: Lower muscle mass has been correlated with poor physical function; however, no studies have examined this relationship prospectively. This study aims to investigate whether low muscle mass, low muscle strength, and greater fat infiltration into the muscle predict incident mobility limitation.

Methods: Our study cohort included 3075 well-functioning black and white men and women aged 70-79 years participating in the Health, Aging, and Body Composition study.

Obesity, regional body fat distribution, and the metabolic syndrome in older men and women.

Background: The metabolic syndrome is a disorder that includes dyslipidemia, insulin resistance, and hypertension and is associated with an increased risk of diabetes and cardiovascular disease. We determined whether patterns of regional fat deposition are associated with metabolic syndrome in older adults.

Methods: A cross-sectional study was performed that included a random, population-based, volunteer sample of Medicare-eligible adults within the general communities of Pittsburgh, Pa, and Memphis, Tenn.

Adipose tissue in muscle: a novel depot similar in size to visceral adipose tissue.

Background: The manner in which fat depot volumes and distributions, particularly the adipose tissue (AT) between the muscles, vary by race is unknown.

Objective: The objective was to quantify a previously unstudied and novel intermuscular AT (IMAT) depot and subcutaneous AT, visceral AT (VAT), and total-body skeletal muscle mass in healthy sedentary African American (AA), Asian, and white adults by whole-body magnetic resonance imaging. IMAT is the AT between muscles and within the boundary of the muscle fascia.

Skeletal muscle fatigue, strength, and quality in the elderly: the Health ABC Study.

We examined the muscle fatigue characteristics in older men and women and determined whether these were related to the size, strength, or quality of muscle. A total of 1,512 men and women aged 70-79 yr from the Health, Aging, and Body Composition Study participated in this study. Muscle cross-sectional area and attenuation were determined with computed tomography.

Predicting the development of diabetes in older adults: the derivation and validation of a prediction rule.

Objective: To create a simple prediction rule that could perform as well as the 2-h postchallenge plasma glucose (PCPG) test to predict those at risk for diabetes. We created a prediction rule in one sample and prospectively validated it for incident diabetes in a separate cohort.

Research Design And Methods: A cross-sectional analysis with data from the Rancho Bernardo Study (age 67 +/- 11 years) to derive a rule predicting abnormal PCPG >/=140 mg/dl, using demographic, clinical, and laboratory data of nondiabetic participants with fasting plasma glucose (FPG) <126 mg/dl.

Deficiency of subsarcolemmal mitochondria in obesity and type 2 diabetes.

The current study addresses a novel hypothesis of subcellular distribution of mitochondrial dysfunction in skeletal muscle in type 2 diabetes. Vastus lateralis muscle was obtained by percutaneous biopsy from 11 volunteers with type 2 diabetes; 12 age-, sex-, and weight-matched obese sedentary nondiabetic volunteers; and 8 lean volunteers. Subsarcolemmal and intermyofibrillar mitochondrial fractions were isolated by differential centrifugation and digestion techniques.

Skeletal muscle lipid accumulation in obesity, insulin resistance, and type 2 diabetes.

In addition to obesity, many factors, including the distribution of body fat, contribute to the development of insulin resistance and type 2 diabetes mellitus (T2DM). Lipid contained within skeletal muscle as triglyceride is a parameter of regional fat accumulation thought to be an important link among obesity, insulin resistance, and type 2 diabetes, even in the pediatric population. Intramuscular triglycerides can also be a fuel source for healthy muscle during periods of physical activity.

Effects of weight loss and physical activity on skeletal muscle mitochondrial function in obesity.

The current study was undertaken to address responsiveness of skeletal muscle mitochondrial electron transport chain (ETC) activity to weight loss (WL) and exercise in overweight or obese, sedentary volunteers. Fourteen middle-aged participants (7 male/7 female) had assessments of mitochondrial ETC activity and mitochondrial (mt)DNA in vastus lateralis muscle, obtained by percutaneous biopsy, before and after a 16-wk intervention. Mean WL was 9.

Serum leptin concentrations and body adipose measures in older black and white adults.

Background: Among US adults, serum leptin concentrations are higher in women than in men and are higher in blacks than in whites independent of anthropometric measures of body fatness.

Objective: Using radiographic measures of body fat, we determined the best correlates of leptin and whether adiposity can explain sex and race differences in leptin concentrations in older adults.

Design: This was a cross-sectional analysis of fasting serum leptin concentrations and body fat measured by dual-energy X-ray absorptiometry (DXA), abdominal computed tomography, and standard anthropometry in 3026 well-functioning 70-79-y-old participants (42% black, 51% women) of the Health, Aging, and Body Composition Study.