Sarcopenia

Evaluation of movement speed and reaction time as predictors of all-cause mortality in men

Muscle power is associated with mortality independent of strength, suggesting that movement speed and coordination convey health-related information. We hypothesized that movement speed is a marker of longevity. Our participants included 1196 men who performed a tapping and/or auditory simple (respond to a sound) and disjunctive (respond to a higher pitched sound) reaction-time tasks while participating in the Baltimore Longitudinal Study of Aging. Mortality was assessed over 40 years. Tapping time was associated with mortality (relative risk [RR] = 1.34 per minute, 95% confidence interval [CI], 1.05-1.70) adjusted for age, and persisted with adjustments for arm strength and power. Simple (RR = 1.17 per 100 ms, 95% CI, 1.03-1.32) and disjunctive (RR = 1.14 per 100 ms, 95% CI, 1.03-1.27) reaction times but not their difference (RR = 1.04 per 100 ms, 95% CI, 0.92-1.19) were associated with mortality after adjustments for age, neurological/psychiatric and neck/arm pain histories. Age-associated impairments in motor control systems but not the decision to move affects longevity.

Sarcopenia, obesity, and inflammation--results from the Trial of Angiotensin Converting Enzyme Inhibition and Novel Cardiovascular Risk Factors study

BACKGROUND

Age-related body-composition changes are associated with health-related outcomes in elders. This relation may be explained by inflammation and hemostatic abnormalities.

OBJECTIVES

Our objectives were to evaluate the relation between body-composition measures [body mass index (BMI), total fat mass, and appendicular lean mass (aLM)] and C-reactive protein (CRP), interleukin 6 (IL-6), and plasminogen activator inhibitor 1 (PAI-1) and to explore the effect of obesity and sarcopenia on CRP, IL-6, and PAI-1 concentrations.

DESIGN

The data are from the Trial of Angiotensin Converting Enzyme Inhibition and Novel Cardiovascular Risk Factors (TRAIN) study baseline visit (n = 286; mean age = 66.0 y). Total fat mass and aLM were assessed with a dual-energy X-ray absorptiometry scan. Linear regressions were performed between body-composition measures and CRP, IL-6, or PAI-1 concentrations. The effect of sarcopenia and obesity (defined as the percentage of fat mass) on CRP, IL-6, and PAI-1 concentrations was evaluated with the use of analyses of covariance.

RESULTS

CRP and IL-6 were positively associated with both BMI [beta = 0.027 (P = 0.03) and beta = 0.048 (P < 0.001), respectively] and total fat mass [beta = 0.049 (P < 0.001) and beta = 0.055 (P < 0.001), respectively] and were inversely associated with fat-adjusted aLM [beta = -0.629 (P = 0.002) and beta = -0.467 (P = 0.02), respectively]. PAI-1 was positively associated with both BMI (beta = 0.038, P = 0.005) and total fat mass (beta = 0.032, P = 0.007). No significant interaction was found between either obesity or sarcopenia and CRP, IL-6, and PAI-1 concentrations. Obesity remained significantly associated with high CRP and IL-6 concentrations after adjustments for sarcopenia.

CONCLUSIONS

CRP and IL-6 are positively associated with total fat mass and negatively associated with aLM. Obesity-associated inflammation may play an important role in the age-related process that leads to sarcopenia. The relation of inflammation with sarcopenia was not independent of any of the considered obesity indexes.

Frailty and the aging male

Frailty occurs in aging males for a variety of reasons. It is less common in males than females. Diseases which are particularly associated with frailty are diabetes mellitus, atherosclerosis, anemia and chronic obstructive pulmonary disease. Insulin resistance syndrome plays a pathogenetic role in the "fat-frail" syndrome. Sarcopenia occurs predominantly because of hormone deficiency and cytokine excess. Pain and anorexia are also associated with frailty. Stem cell research represents a potential promise for the treatment of frailty.

Sarcopenia, obesity, and inflammation--results from the Trial of Angiotensin Converting Enzyme Inhibition and Novel Cardiovascular Risk Factors study

BACKGROUND

Age-related body-composition changes are associated with health-related outcomes in elders. This relation may be explained by inflammation and hemostatic abnormalities.

OBJECTIVES

Our objectives were to evaluate the relation between body-composition measures [body mass index (BMI), total fat mass, and appendicular lean mass (aLM)] and C-reactive protein (CRP), interleukin 6 (IL-6), and plasminogen activator inhibitor 1 (PAI-1) and to explore the effect of obesity and sarcopenia on CRP, IL-6, and PAI-1 concentrations.

DESIGN

The data are from the Trial of Angiotensin Converting Enzyme Inhibition and Novel Cardiovascular Risk Factors (TRAIN) study baseline visit (n = 286; mean age = 66.0 y). Total fat mass and aLM were assessed with a dual-energy X-ray absorptiometry scan. Linear regressions were performed between body-composition measures and CRP, IL-6, or PAI-1 concentrations. The effect of sarcopenia and obesity (defined as the percentage of fat mass) on CRP, IL-6, and PAI-1 concentrations was evaluated with the use of analyses of covariance.

RESULTS

CRP and IL-6 were positively associated with both BMI [beta = 0.027 (P = 0.03) and beta = 0.048 (P < 0.001), respectively] and total fat mass [beta = 0.049 (P < 0.001) and beta = 0.055 (P < 0.001), respectively] and were inversely associated with fat-adjusted aLM [beta = -0.629 (P = 0.002) and beta = -0.467 (P = 0.02), respectively]. PAI-1 was positively associated with both BMI (beta = 0.038, P = 0.005) and total fat mass (beta = 0.032, P = 0.007). No significant interaction was found between either obesity or sarcopenia and CRP, IL-6, and PAI-1 concentrations. Obesity remained significantly associated with high CRP and IL-6 concentrations after adjustments for sarcopenia.

CONCLUSIONS

CRP and IL-6 are positively associated with total fat mass and negatively associated with aLM. Obesity-associated inflammation may play an important role in the age-related process that leads to sarcopenia. The relation of inflammation with sarcopenia was not independent of any of the considered obesity indexes.

Serum Albumin and Muscle Strength: A Longitudinal Study in Older Men and Women

OBJECTIVES

To examine whether low serum albumin is associated with low muscle strength and future decline in muscle strength in community-dwelling older men and women.

DESIGN

Population-based cohort study.

SETTING

The Longitudinal Aging Study Amsterdam.

PARTICIPANTS

Six hundred seventy-six women and 644 men aged 65 to 88.

MEASUREMENTS

Serum albumin was determined at baseline. Muscle strength was assessed using grip strength at baseline, after 3 (n=1,009), and 6 (n=741) years. The outcomes were continuous baseline muscle strength, 3- and 6-year change in muscle strength, and a dichotomous indicator for substantial decline (a decrease if > or =1 standard deviations for women=11 kg, for men=12 kg) in muscle strength.

RESULTS

Mean serum albumin concentration+/-standard deviation was 45.0+/-3.3 g/L for women and 45.2+/-3.2 g/L for men. At baseline, adjusting for age, lifestyle factors, and chronic conditions, lower serum albumin was cross-sectionally associated with weaker muscle strength (P<.001) in women and men. After 3 years of follow-up, mean decline in muscle strength was -5.6+/-10.9 kg in women and -9.6+/-11.9 kg in men. After adjustment for potential confounders, lower serum albumin was associated with muscle strength decline over 3 years (P<.01) in women and men (beta=0.57, standard error (SE)=0.18; beta=0.37, SE=0.16, respectively). Lower serum albumin was also associated with substantial decline in muscle strength in women (per unit albumin (g/L) adjusted odds ratio (OR)=1.14, one-sided 95% confidence limit (CL)=1.07) and men (per unit albumin (g/L) adjusted OR=1.14, 95% CL=1.08). Similar but slightly weaker associations were found between serum albumin and 6-year change in muscle strength (P<.05).

CONCLUSION

These results suggest that low serum albumin, even within the normal range, is independently associated with weaker muscle strength and future decline in muscle strength in older women and men.

Sarcopenia is related to physical functioning and leg strength in middle-aged women

BACKGROUND

In the aging process, loss of muscle is relatively continuous, but the initiation, timing, and amount of muscle loss that relate to functional compromise are poorly described. Also poorly understood is whether strength and functioning in aging are related to the amount of lean mass and its change as well as to the amount of fat mass and its change.

METHODS

The purpose of the study was to ascertain whether 3-year lean and fat mass change predicted functional status in 712 African American and Caucasian women, aged 34-58 years. Fat and lean mass were assessed with bioelectrical impedance. Lower leg strength (torque) was measured with a portable isometric chair, and two indices of physical functioning, walking velocity and double support (both feet touching the surface while walking), were measured with an instrumented gait mat.

RESULTS

Almost 9% of middle-aged women had at least a 6% loss (>2.5 kg) of lean mass over the 3-year observation period. Women who lost at least 2.5 kg of lean mass had slower walking velocity and less leg strength, although women who simultaneously gained more than 2.5 kg of fat mass (at least 7.5%) did not have less leg strength. Age was significantly associated with less velocity, less leg strength, and more time in double support.

CONCLUSIONS

Even in middle-aged women, there is loss of lean mass among almost 1 woman in 10, and this loss of lean mass (sarcopenia) is associated with greater compromise in physical functioning.

Metabolic consequences of muscle disuse atrophy

In response to decreased usage, skeletal muscle undergoes an adaptive reductive remodeling. This adaptive response has been found with disuse during human spaceflight, rat spaceflight, rat hind-limb unloading, bed rest, and aging. The reductive remodeling of skeletal muscle with disuse is largely independent of the reason for the disuse. The process involves more than a transition from slow to fast myosin fiber types. There are associated metabolic changes including a fuel shift toward glycolysis, decreased capacity for fat oxidation, and energy substrate accumulation in the atrophied muscles. Glycolysis is very effective for high-intensity short-duration acute activities, but if sustained output is needed, an energy profile where fat use is favored rather than compromised is desirable. For astronauts, there is a need to maintain as much functional capacity as possible during spaceflight for extravehicular activities. The shift toward increased activity of the glycolytic enzymes in atrophied muscle is accommodated by an increase in gluconeogenic capacity in the liver.

Preventing and treating the complications of hormone therapy

Hormonal manipulation in the form of androgen-deprivation therapy for prostate cancer was introduced by Huggins and Hodges in 1941 and resulted in a Nobel Prize in 1966. Hormonal therapy initially had been used in metastatic prostate cancer, but the indications have been expanded including failed local therapy, locally advanced prostate cancer, and neoadjuvant or adjuvant therapy in high-risk localized prostate cancer. In view of the magnitude of the problem of prostate cancer and relatively frequent use of hormonal manipulation, it is important for clinicians to be aware of common side effects, prevention, and treatment to improve quality of life and reduce morbidity and mortality in patients with prostate cancer. This review focuses on the common side effects of hormonal treatment such as osteoporosis, anemia, hot flashes, erectile dysfunction, muscle wasting, gynecomastia, decline in cognitive function, depression, increase in body fat and metabolic changes, and their prevention and treatment.

Low skeletal muscle mass is associated with poor structural parameters of bone and impaired balance in elderly men--the MINOS study

In 796 men, 50-85 years of age, decreased relative skeletal muscle mass index was associated with narrower bones, thinner cortices, and a consequent decreased bending strength (lower section modulus), as well as with impaired balance and an increased risk of falls.

INTRODUCTION

In men, appendicular skeletal muscle mass (ASM) is correlated positively with BMC and areal BMD (aBMD). In elderly men, low muscle mass and strength (sarcopenia) is associated with difficulties in daily living activities. The aim of this study was to evaluate if ASM is correlated with bone size, mechanical properties of bones, balance, and risk of falls in elderly men.

MATERIALS AND METHODS

This study used 796 men, 50-85 years of age, belonging to the MINOS cohort. Lifestyle factors were evaluated by standardized questionnaires. Estimates of mechanical bone properties were derived from aBMD measured by DXA. ASM was estimated by DXA. The relative skeletal muscle mass index (RASM) was calculated as ASM/(body height)(2.3).

RESULTS

After adjustment for age, body size, tobacco smoking, professional physical activity, and 17beta-estradiol concentration, RASM was correlated positively with BMC, aBMD, external diameter, and cortical thickness (r = 0.17-0.34, p < 0.0001) but not with volumetric BMD. Consequently, RASM was correlated with section modulus (r = 0.29-0.39, p < 0.0001). Men in the lowest quartile of RASM had section modulus of femoral neck and distal radius lower by 12-18% in comparison with men in the highest quartile of RASM. In contrast, bone width was not correlated with fat mass, reflecting the load of body weight (except for L(3)), which suggests that the muscular strain may exert a direct stimulatory effect on periosteal apposition. After adjustment for confounding variables, a decrease in RASM was associated with increased risk of falls and of inability to accomplish clinical tests of muscle strength, static balance, and dynamic balance (odds ratio per 1 SD decrease in RASM, 1.31-2.23; p < 0.05-0.001).

CONCLUSIONS

In elderly men, decreased RASM is associated with narrower bones and thinner cortices, which results in a lower bending strength. Low RASM is associated with impaired balance and with an increased risk of falls in elderly men. It remains to be studied whether low RASM is associated with decreased periosteal apposition and with increased fracture risk in elderly men, and whether the difference in skeletal muscle mass between men and women contributes to the between-sex difference in fracture incidence.

Of worms and women: sarcopenia and its role in disability and mortality

The loss of muscle mass during aging has been termed sarcopenia. Sarcopenia results in a decrease in physical strength during aging that results in important consequences for more severely affected individuals in terms of function and as a marker for disability and increased mortality. Despite the clinical importance of this condition, the pathophysiology leading to the development of sarcopenia is not well understood, and few treatments exist to prevent or reverse the condition. Recently, sarcopenia has been found to occur during aging in the nematode Caenorhabditis elegans, which is an organism increasingly used to study genetic and biochemical events involved in aging. Like in humans, sarcopenia in C. elegans leads to declines in mobility and serves as a marker for increased mortality. Interestingly, mutations affecting the age-1 gene, which slows aging of the animal, result in significant delays in the development of sarcopenia, suggesting a direct causal relationship between organismal aging and sarcopenia. These findings suggest that, in humans and worms, sarcopenia may represent a biomarker for the biological age, as opposed to chronological age, of the individual. These findings also suggest that C. elegans will develop into an important model system in which to study the biochemical and genetics events responsible for sarcopenia and to test therapeutics designed to prevent or reverse sarcopenia.

Role of Protein and Amino Acids in the Pathophysiology and Treatment of Sarcopenia

Sarcopenia, the loss of skeletal muscle mass and function with aging, is a multifactorial condition that slowly develops over decades and becomes a significant contributor to disability in the older population. Malnutrition and alterations in the muscle anabolic response to nutritional stimuli have been identified as potentially preventable factors that may significantly contribute to sarcopenia. Thus, nutritional interventions may be useful for the prevention and treatment of sarcopenia.

Beta2-agonist administration increases sarcoplasmic reticulum Ca2+-ATPase activity in aged rat skeletal muscle

Aging is associated with a slowing of skeletal muscle contractile properties, including a decreased rate of relaxation. In rats, the age-related decrease in the maximal rate of relaxation is reversed after 4-wk administration with the beta2-adrenoceptor agonist (beta2-agonist) fenoterol. Given the critical role of the sarcoplasmic reticulum (SR) in regulating intracellular Ca2+ transients and ultimately the time course of muscle contraction and relaxation, we tested the hypothesis that the mechanisms of action of fenoterol are mediated by alterations in SR proteins. Sarcoendoplasmic reticulum Ca2+-ATPase (SERCA) kinetic properties were assessed in muscle homogenates and enriched SR membranes isolated from the red (RG) and white (WG) portions of the gastrocnemius muscle in adult (16 mo) and aged (28 mo) F344 rats that had been administered fenoterol for 4 wk (1.4 mg/kg/day ip, in saline) or vehicle only. Aging was associated with a 29% decrease in the maximal activity (Vmax) of SERCA in the RG but not in the WG muscles. Fenoterol treatment increased the Vmax of SERCA and SERCA1 protein levels in RG and WG. In the RG, fenoterol administration reversed an age-related selective nitration of the SERCA2a isoform. Our findings demonstrate that the mechanisms underlying age-related changes in contractile properties are fiber type dependent, whereas the effects of fenoterol administration are independent of age and fiber type.

Emerging drugs for sarcopenia: age-related muscle wasting

Sarcopenia is the term widely used to describe the progressive loss of muscle mass with advancing age. Even before significant muscle wasting becomes apparent, ageing is associated with a slowing of movement and a gradual decline in muscle strength, factors that increase the risk of injury from sudden falls and the reliance of the frail elderly on assistance in accomplishing even basic tasks of independent living. Sarcopenia is recognised as one of the major public health problems now facing industrialised nations, and its effects are expected to place increasing demands on public healthcare systems worldwide. Although the effects of ageing on skeletal muscle are unlikely to be halted or reversed, the underlying mechanisms responsible for these deleterious changes present numerous targets for drug discovery with potential opportunities to attenuate muscle wasting, improve muscle function, and preserve functional independence. Very few drugs have been developed with sarcopenia specifically in mind. However, because many of the effects of ageing on skeletal muscle resemble those indicated in many neuromuscular disorders, drugs that target neurodegenerative diseases may also have important relevance for treating age-related muscle wasting and weakness. This review describes a selection of the emerging drugs that have been developed during the period 1997 - 2004, relevant to sarcopenia.

Effects of aging on muscle fibre type and size

Aging has been associated with a loss of muscle mass that is referred to as 'sarcopenia'. This decrease in muscle tissue begins around the age of 50 years, but becomes more dramatic beyond the 60th year of life. Loss of muscle mass among the aged directly results in diminished muscle function. Decreased strength and power contribute to the high incidence of accidental falls observed among the elderly and can compromise quality of life. Moreover, sarcopenia has been linked to several chronic afflictions that are common among the aged, including osteoporosis, insulin resistance and arthritis. Loss of muscle fibre number is the principal cause of sarcopenia, although fibre atrophy--particularly among type II fibres--is also involved. Several physiological mechanisms have been implicated in the development of sarcopenia. Denervation results in the loss of motor units and thus, muscle fibres. A decrease in the production of anabolic hormones such as testosterone, growth hormone and insulin-like growth factor-1 impairs the capacity of skeletal muscle to incorporate amino acids and synthesise proteins. An increase in the release of catabolic agents, specifically interleukin-6, amplifies the rate of muscle wasting among the elderly. Given the demographic trends evident in most western societies, i.e. increased number of those considered aged, management interventions for sarcopenia must become a major goal of the healthcare profession.

A novel cell-based system for evaluating skeletal muscle cell hypertrophy-inducing agents

Skeletal muscle is a tissue that adapts to increased use by increasing contractile protein gene expression and ultimately skeletal muscle mass (hypertrophy). To identify hypertrophy-inducing agents that may be potentially useful in the treatment of age-related muscle loss (sarcopenia) and to better understand hypertrophy signal transduction pathways, we have created a skeletal muscle cell-based hypertrophy-responsive system. This system was created by permanently modifying the relatively undifferentiated C2C12 cell line so that it contains the beta-myosin heavy chain (beta-MHC) gene promoter and enhancer regions fused to a luciferase reporter gene. This cell line responds, by increasing luciferase expression, to a variety of skeletal muscle hypertrophy-inducing agents, including insulin, insulin-like growth factor I, testosterone, and the beta-adrenergic receptor agonist isoproterenol, in both the undifferentiated and differentiated states. This cell-based system should be useful for identifying novel hypertrophy-inducing agents as well as understanding hypertrophy signal transduction.

Prevalence of and Risk Factors for Sarcopenia in Elderly Chinese Men and Women

BACKGROUND

Several studies have documented the substantial health and economic burdens associated with sarcopenia among the elderly, but there has been no systematic study among Asians. A cross-sectional survey of elderly community-dwelling Chinese volunteers (262 men and 265 women), aged 70 years and older, was undertaken in Hong Kong. The purposes of this study were to evaluate the prevalence of and risk factors for sarcopenia in elderly Chinese, and to compare these observations with those in white persons.

METHODS

Muscle mass was estimated by dual-energy X-ray absorptiometry. In this study, sarcopenia was defined as a total adjusted skeletal muscle mass two standard deviations or more below the normal mean for young Asian men and women in this study. The relationship between risk factors (alcohol consumption, cigarette smoking, regular exercise, body mass index, medical conditions) and sarcopenia was studied by multiple logistic regression.

RESULTS

The prevalence of sarcopenia was 12.3% in Chinese men and 7.6% in Chinese women aged 70 years and older, which was slightly lower than figures observed in white persons. Being underweight was a significant risk factor in both men (odds ratio, 39.1; 95% confidence interval, 11.3 to 134.6) and women (odds ratio, 9.7; 95% confidence interval, 2.8 to 33.8). No other risk factors were found in Chinese men or women.

CONCLUSIONS

Sarcopenia exists among elderly Chinese men and women, albeit at a lower rate than in white persons. This may be due to the lower muscle mass among young men and women or to an attenuated rate of loss in muscle mass with aging in the Chinese elderly. Being underweight is a major risk factor for sarcopenia in both sexes.

Muscle fiber specific apoptosis and TNF-alpha signaling in sarcopenia are attenuated by life-long calorie restriction

Increased tumor necrosis factor-alpha (TNF-alpha) levels have been found with age and are connected to muscle atrophy and cell loss, yet the signaling events that occur in vivo are unknown. Calorie restriction (CR), a robust intervention shown to repeatedly evade the physiological declines associated with aging, has been reported to reduce TNF-alpha and may assist in understanding the mechanisms of muscle sarcopenia. The effects of age and CR on muscle mass, myocyte area, fiber number, myocyte TNF-alpha expression, plasma TNF-alpha levels, and specific elements linked with the TNF-alpha signaling cascade (TNF-R1, IKKgamma, IkappaBalpha, p65, NF-kappaB binding activity, FADD, caspase-8, and DNA fragmentation) were investigated in soleus (predominately Type I fiber), and superficial vastus lateralis (SVL, predominately Type II fiber), of 6-month-old ad libitum fed (6AL), 26-month-old ad libitum fed (26AL), and 26-month-old calorie-restricted (26CR) male Fischer 344 rats (CR = 40% restriction compared with ad libitum). Plasma TNF-alpha was increased with age, and the age-associated rise was attenuated with life-long CR. In soleus muscle, we reported a greater capacity to cultivate inflammatory signaling through the transcription factor NF-kappaB compared with that detected in SVL with age. In contrast, in the SVL TNF-alpha stimulated apoptotic signaling with age to a much higher extent than was observed in the soleus. Moreover, a reduction in muscle mass, cross-sectional area, and fiber number in the SVL coincided with this age-linked elevation in apoptosis. In agreement with CR's ability, TNF-alpha stimulation of both inflammatory and apoptotic pathways were abrogated. Our results suggest that TNF-alpha signals transmitted to specific fiber types determine the decision of selecting life or death signaling pathways and are linked to the extent of fiber loss experienced in the aging muscle. Such a specific potential may constitute a major proponent in the pathogenesis of sarcopenia.

Due to reverse electron transfer, mitochondrial H2O2 release increases with age in human vastus lateralis muscle although oxidative capacity is preserved

Age-related changes in mitochondrial H2O2 release (MHR) could be responsible for an increase in oxidative stress in skeletal muscle and participate in the development of sarcopenia. We compared MHR in vastus lateralis biopsies obtained from young (23.5+/-2.0 year, n=6) and elderly (67.3+/-1.5 year, n=6) healthy sedentary men. Isolated mitochondria were incubated in the presence of glutamate/malate/succinate, with or without rotenone. Muscle fat oxidative capacity, citrate synthase, complex II, complex III, and cytochrome c oxidase activities were also measured. In parallel, we analyzed in gastrocnemius of young male Wistar rats (n=6), the impact of lidocaine (local anesthetic used in humans) on mitochondrial respiration and MHR. In humans, muscle oxidative capacity was preserved with age but muscle MHR was markedly enhanced in elderly subjects compared to young adults (+175%, P<0.05). Rotenone abolished this increase, demonstrating that it was due to a free radical release during reverse electron transfer from complex II towards complex I. Lidocaine can interfere with MHR measurements (intra-muscular injection in rats) but it can be avoided by minimizing contact with muscle (small multiple subcutaneous injections in humans). Physiologic consequences of the observed increase in muscle MHR with aging remain to be determined.

Old and alone: barriers to healthy eating in older men living on their own

Ageing is associated with reduced energy intake and loss of appetite. Older men tend to have poorer dietary intakes including consumption of fewer fruits and vegetables in comparison to older women. Living and eating alone further diminishes food consumption and dietary quality. The aim of the present study was to explore food choice and energy intake in older men living alone using both quantitative and qualitative methods. 39 older men were interviewed and completed questionnaires on health, food choice, dietary patterns and appetite. Few men managed to consume recommended levels of energy, essential trace elements or vitamins A and D. Age and BMI failed to predict patterns of intake, but men with good cooking skills reported better physical health and higher intake of vegetables. However, cooking skills were negatively correlated with energy intake. Men who managed to consume at least 4 portions of fruits and vegetables each day had significantly higher vitamin C levels, a greater percentage of energy as protein and generally more adequate diets. Interviews revealed that poor cooking skills and low motivation to change eating habits may constitute barriers to improving energy intake, healthy eating and appetite in older men (193).

Postexercise protein metabolism in older and younger men following moderate-intensity aerobic exercise

Regular aerobic exercise strongly influences muscle metabolism in elderly and young; however, the acute effects of aerobic exercise on protein metabolism are not fully understood. We investigated the effect of a single bout of moderate walking (45 min at approximately 40% of peak O2 consumption) on postexercise (POST-EX) muscle metabolism and synthesis of plasma proteins [albumin (ALB) and fibrinogen (FIB)] in untrained older (n = 6) and younger (n = 6) men. We measured muscle phenylalanine (Phe) kinetics before (REST) and POST-EX (10, 60, and 180 min) using l-[ring-2H5]phenylalanine infusion, femoral arteriovenous blood samples, and muscle biopsies. All data are presented as the difference from REST (at 10, 60, and 180 min POST-EX). Mixed muscle fractional synthesis rate (FSR) increased significantly at 10 min POST-EX in both the younger (0.0363%/h) and older men (0.0830%/h), with the younger men staying elevated through 60 min POST-EX (0.0253%/h). ALB FSR increased at 10 min POST-EX in the younger men only (2.30%/day), whereas FIB FSR was elevated in both groups through 180 min POST-EX (younger men = 4.149, older men = 4.107%/day). Muscle protein turnover was also increased, with increases in synthesis and breakdown in younger and older men. Phe rate of disappearance (synthesis) was increased in both groups at 10 min POST-EX and remained elevated through 60 min POST-EX in the older men. A bout of moderate-intensity aerobic exercise induces short-term increases in muscle and plasma protein synthesis in both younger and older men. Aging per se does not diminish the protein metabolic capacity of the elderly to respond to acute aerobic exercise.

Does Sarcopenia Originate in Early Life? Findings From the Hertfordshire Cohort Study

BACKGROUND

Sarcopenia is defined as the loss of skeletal muscle mass and strength with aging. Recent epidemiological studies have shown that men and women who grew less well in early life have lower muscle strength. Our objective was to investigate the relationship between birth weight, infant growth, and the development of sarcopenia.

METHODS

We studied 730 men and 673 women, of known birth weight and weight at 1 year, who were born in Hertfordshire, U.K., between 1931 and 1939. Participants completed a health questionnaire, and we measured their height, weight, and grip strength. Standard deviation scores for birth weight, and for infant growth conditional on birth weight, were analyzed in relation to grip strength before and after adjustment for adult size.

RESULTS

Grip strength was most strongly associated with birth weight in men (r = 0.19, p < .001) and women (r = 0.16, p < .001). These relationships remained significant after adjustment for adult height and weight. In contrast, the associations with infant growth were weakened after allowing for adult size. Adjustment for age, current social class, physical activity, smoking, and alcohol did not affect these results.

CONCLUSIONS

Birth weight is associated with sarcopenia in men and women, independently of adult height and weight. The influence of infant growth on long-term muscle strength appears to be mediated through adult size. Sarcopenia may have its origins in early life, and identifying influences operating across the whole life course may yield considerable advances in developing effective interventions.

Hormonal and lifestyle determinants of appendicular skeletal muscle mass in men: the MINOS study

BACKGROUND

Aging-related sarcopenia is characterized by a loss of muscle mass and strength and increased fatigability. However, studies of its determinants in elderly men are scarce.

OBJECTIVE

We investigated risk factors for sarcopenia in a large cohort of men.

DESIGN

We analyzed 845 men aged 45-85 y who belonged to the MINOS cohort. Lifestyle factors (physical activity, tobacco smoking, alcohol intake, caffeine intake) were evaluated by using a standardized questionnaire. Appendicular skeletal muscle mass (ASM) was estimated by using dual-energy X-ray absorptiometry. The relative appendicular skeletal muscle mass index (RASM) was calculated as ASM/body height(2.3). Apparent free testosterone concentration (AFTC) and free testosterone index (FTI) were calculated on the basis of concentrations of total testosterone and sex hormone-binding globulin.

RESULTS

RASM decreased with age (r = -0.29, P < 0.0001). Current smokers had lower RASM than did subjects who never smoked (-3.2%; P < 0.003). RASM increased with the intensity of physical activity at work (P for trend < 0.001). Men who participated in regular exercise during leisure time had 2.2% higher RASM than did those who did not (P < 0.03). Men whose values for AFTC, FTI, or 25-hydroxycholecalciferol [25(OH)D] were >2 SDs below the mean for young men had significantly lower RASM than did men with higher values. Men with sarcopenia, defined as the lowest quartile of RASM in the studied cohort (<6.32 kg/m(2.3)), were significantly older than men with normal RASM, weighed significantly less, smoked more, and spent significantly less time on leisure-time activities. Sarcopenic men also had lower values for testosterone, AFTC, FTI, and 25(OH)D.

CONCLUSION

In elderly men, low physical activity, tobacco smoking, thinness, low testosterone (AFTC and FTI), and decreased 25(OH)D concentrations are risk factors for sarcopenia.

Pharmacoepidemiology and disability in older adults: can medications slow the age-related decline in physical function?

Age-related disability and loss in physical function are growing public health priorities. Loss in physical function seriously threatens the independence and quality of life of older adults and has a significant social and economic impact on our society. Despite the fact that the negative impact of adverse drug reaction and inappropriate drug use on disability has been widely studied, there is limited evidence regarding the efficacy of pharmacological interventions to prevent decline in physical function among older populations. The effect of statins, angiotensin-converting enzyme inhibitors and testosterone on physical performance in older adults are reviewed. In clinical studies these drugs have recently shown promising effects on the prevention of disability and decline in physical function in older adults. The findings of these studies are not definite and need to be confirmed in large clinical trials.

The effects of whole body vibration on humans: dangerous or advantageous?

The effects of whole body vibration (WBV) have been studied extensively in occupational medicine. In particular, it has been shown that when the body undergoes chronically to whole body vibrations spinal degeneration is likely to be one of the deleterious outcomes. Low back pain has been shown to be the leading major cause of industrial disability in the population under the age of 45 years and has been linked to whole body vibration exposure encountered in some industrial settings. Whole body vibration has been recently purposed as an exercise intervention suggesting its effectiveness in increasing force-generating capacity in lower limbs and low back. It has also been reported to be an effective non-pharmacological intervention for patients with low back pain. Relatively short exposure to whole body vibration has been also shown to increase the serum levels of testosterone and growth hormone. The combined effects on the neuromuscular system and endocrine system seem to suggest its effectiveness as a therapeutic approach for sarcopenia and possibly osteoporosis. Due to the danger of long-term exposure to whole body vibration, it is important to develop safe exercise protocols in order to determine exercise programs for different populations.

Anti-aging medicine--the good, the bad, and the ugly

Complementary and alternative medicine has flourished since the beginning of time because of a human need to postpone the aging process and to reverse disease. Complementary and alternative medicine sells, because in some cases it works as well or better than mainstream medicine. In addition, many practitioners of complementary medicine understand Hippocrates' aphorism: "It is more important to know the person that has the disease than the disease the person has." It is important to recognize that spending time with the patient is often as therapeutic as drugs. CAM offers patients the time, touch, attention, and level of personal interaction that are increasingly uncommon in contemporary medical care. There is a major need for large and appropriately designed studies to test the effectiveness of complementary techniques. As in other areas of health care, studies in the elderly are consistently lacking. With the growing interest in CAM, it is important for medical providers to keep an open mind--to both the potential benefits and potential harms of alternative treatments. When treatments are shown to be dangerous or ineffective, we must educate the public and work to remove these therapies from the market place. When treatments are proven effective, Western and Eastern medical providers must work together with patients to provide the most appropriate and comprehensive health care.

Sarcopenia and increased adipose tissue infiltration of muscle in elderly African American women

BACKGROUND

Aging is associated with metabolic, physiologic, and functional impairments, in part through age-related changes in body composition. During the later adult years, skeletal muscle mass decreases and body fat becomes centralized.

OBJECTIVE

The goal of the study was to investigate body composition over time ( +/- SD: 2.04 +/- 0.6 y) in healthy, ambulatory, elderly African American women. The hypothesis that a reduction in total-body skeletal muscle (SM) and increases in visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and intermuscular adipose tissue (IMAT) are ongoing in healthy, weight-stable elderly was tested.

DESIGN

The study was a longitudinal evaluation of 26 women (age at baseline: 75.5 +/- 5.1 y) with a body mass index (in kg/m(2)) of 27.0 +/- 4.0. Body composition was measured by using whole-body magnetic resonance imaging for the quantification of SM, total adipose tissue (TAT), VAT, SAT, and IMAT.

RESULTS

SM (P < 0.001) and bone (P < 0.05) masses decreased, and regional analyses showed a decrease in dual-energy X-ray absorptiometry-derived leg SM (P < 0.05). VAT (P = 0.011) and IMAT (P < 0.001) increased. No changes occurred in TAT (P = 0.45), SAT (P = 0.96), physical function, or food intake.

CONCLUSION

These data show an age-related remodeling of body composition with reductions in SM and corresponding increases in VAT and IMAT. Changes in the previously unstudied depot of IMAT may be involved in the deterioration of metabolic values frequently observed during aging.

Hormonal fountains of youth

Any hope of a fountain of youth to stop people from getting older is a long way off, with science just beginning to understand the complex genetic, physical, and hormonal causes of aging. Clearly, modem research has demonstrated that the concept of a hormonal fountain of youth is predominantly mythology. The best evidence supporting use of hormonal replacement is vitamin D and estrogen replacement to prevent hip fractures. Other than that, treatment should be limited to hormone replacement in persons who have endocrine disease.

Physical disability and muscular strength in relation to obesity and different body composition indexes in a sample of healthy elderly women

OBJECTIVES

The aim of the present study was to test the association between muscular strength, functional limitations, body composition measurements and indexes of sarcopenia in a sample of community-dwelling, elderly women at the high end of the functional spectrum.

DESIGN

Cross-sectional.

SUBJECTS

In all, 167 women aged 67-78 y were selected from the general population in central Verona. A group of 120 premenopausal healthy women aged 20-50 y represented the young reference group.

MEASUREMENTS

Body weight, height, body mass index (BMI) and the presence of acute and chronic conditions were evaluated in each subject. Body composition was measured by dual-energy X-ray absorptiometry (DXA). Physical functioning was assessed using a modified version of the Activities of Daily Living Scale. Dominant leg isometric strength was measured with a Spark Handheld Dynamometer.

RESULTS

Elderly women with BMI higher than 30 kg/m(2) and in the highest quintile of body fat percent showed a significantly higher prevalence of functional limitation. In our population study, about 40% of sarcopenic elderly women and 50% of elderly women with high body fat and normal muscle mass were functionally limited. The prevalence of functional limitation significantly increased in subjects with class II sarcopenia, defined according to the skeletal muscle mass index (SMI=skeletal muscle mass/body mass x 100). In logistic regression models, after adjusting for age and different chronic health conditions, subjects with BMI higher than 30 kg/m(2), in the highest quintile of body fat, or with high body fat and normal muscle mass or class II sarcopenia according to SMI, had a 3-4 times increased risk of functional limitations. Finally, isometric leg strength was significantly lower in subjects in the lowest quintile of relative muscle mass and in sarcopenic and sarcopenic obese women.

CONCLUSIONS

High body fat and high BMI values were associated with a greater probability of functional limitation in a population of elderly women at the high end of the functional spectrum. Among the different indexes of sarcopenia used in this study, only SMI predicted functional impairment and disability. Isometric leg strength was significantly lower in subjects with sarcopenia and sarcopenic obesity.

Gene expression profiling of human satellite cells during muscular aging using cDNA arrays

It is well established that biological aging is associated with functional deficits at the cellular, tissue, organ and system levels, but the molecular mechanisms that control lifespan and age-related phenotypes are still not well understood. In order to investigate the molecular mechanisms underlying myoblast aging, we have used quantitative hybridization of a cDNA array of 2016 clones from a human skeletal muscle 3'-end cDNA library to monitor gene expression patterns of myoblasts of individuals with different ages (5 days old, 52 years old and 79 years old) and at different stages of proliferation (early, presenescent and senescent). We have shown that expression profiles in satellite cells vary with donor age, with an up-regulation of genes involved in muscle structure, muscle differentiation and in metabolism in the newborn, and a down-regulation of genes involved in protein renewal in adults. We have also observed that myoblasts isolated from subjects of different ages have typical expression profiles at the beginning of their proliferative lifespan. However, this phenomenon progressively disappears as the cells approach senescence. In addition, even though some of the modifications are similar to those observed in other cell types, we have observed that many changes in gene expression are characteristic of the myoblasts, confirming the hypothesis that the program of replicative senescence is specific for each cell type. Finally, we have identified four potential new markers of presenescence for human myoblasts, which could be useful in developing therapeutic strategies.

Sarcopenia: alternative definitions and associations with lower extremity function

OBJECTIVES

To compare two sarcopenia definitions and examine the relationship between them and lower extremity function and other health related factors using data from the baseline examination of the Health Aging and Body Composition (Health ABC) Study.

DESIGN

Observational cohort study.

SETTING

Two U.S. communities in Memphis, Tennessee, and Pittsburgh, Pennsylvania.

PARTICIPANTS

Participants were aged 70 to 79 (N=2984, 52% women, 41% black).

MEASUREMENTS

Participants were assessed using dual energy x-ray absorptiometry and were classified as sarcopenic using two different approaches to adjust lean mass for body size: appendicular lean mass divided by height-squared (aLM/ht2) and appendicular lean mass adjusted for height and body fat mass (residuals).

RESULTS

These methods differed substantially in the classification of individuals as being sarcopenic, especially those who were more obese. The former method was highly correlated with body mass index and identified fewer overweight or obese individuals as sarcopenic. In both men and women, none of the obese group would be considered sarcopenic using the aLM/ht2 method, compared with 11.5% of men and 21.0% of women using the residuals method. In men, both classifications of sarcopenia were associated with smoking, poorer health, lower activity, and impaired lower extremity function. Fewer associations with health factors were noted in women, but the classification based on both height and fat mass was more strongly associated with lower extremity functional limitations (odds ratio (OR)=0.9, 95% confidence interval (CI)=0.7-1.2 for low kg/ht2; OR=1.9, 95% CI=1.4-2.5 for lean mass adjusted for height and fat mass).

CONCLUSION

These findings suggest that fat mass should be considered in estimating prevalence of sarcopenia in women and in overweight or obese individuals.

Arm-cranking muscle power and arm isometric muscle strength are independent predictors of all-cause mortality in men

Poor muscle strength is associated with mortality, presumably due to low muscle mass. Notably, muscle power declines more rapidly than muscle strength with increasing age, which may be related to more complex central nervous system movement control. We examined arm-cranking power against four workloads and isometric strength measured in the upper extremities of 993 men longitudinally tested over a 25-yr period. Muscle mass was estimated by using 24-h creatinine excretion; physical activity was assessed by self-reported questionnaire. Muscle power and strength were modeled by time by using mixed-effects models, which developed regression equations for each individual. The first derivative of these equations estimated rate of change in strength or power at each evaluation. Survival analyses, using the counting method, examined the impact of strength, power, and their rates of change on all-cause mortality while adjusting for age. Arm-cranking power [relative risk ( rr) = 0.984 per 100 kg·m·min-1, P < 0.001] was a stronger predictor of mortality than was arm strength ( rr = 0.986 per 10 kg, P = not significant), whereas rate of power change ( rr = 0.989 per 100 kg·min-1·yr-1) and rate of arm strength change ( rr = 0.888 per 10 kg/yr) were risks independent of the power or strength levels. The impacts of power and strength were partially independent of muscle mass and physical activity. The risk of mortality was similar across the four power workloads ( rr = 0.93-0.96 per 100 kg·m·min-1), whereas the lowest load generated less than one-half the power as the higher loads. Arm-cranking power is a risk factor for mortality, independent of muscle strength, physical activity, and muscle mass. The impact is found with loads that do not generate maximal power, suggesting an important role for motor coordination and speed of movement.

Calorie restriction limits the generation but not the progression of mitochondrial abnormalities in aging skeletal muscle

The effect of early-onset calorie restriction and aging on the accumulation of electron transport system (ETS) abnormalities was studied in rat skeletal muscle. Rectus femoris and vastus lateralis muscle fibers were analyzed for cytochrome c oxidase (COX) and succinate dehydrogenase (SDH) enzyme activities. Fibers displaying COX negative and SDH hyper reactive (COX-/SDH++) phenotype were followed through 1000-2000 micrometers to determine the frequency and length of these abnormalities as well as the physiological impact on fiber structure. Calorie restricted rats had fewer ETS abnormal muscle fibers. The mean length of ETS abnormal regions in ad libitum rat muscle fibers was similar to calorie restricted rat muscles. ETS abnormal fibers from both diet groups exhibited intra-fiber atrophy. A negative correlation between ETS abnormality length and fiber cross-sectional area (CSA) ratio was observed in both ad libitum and calorie- restricted rats. Although calorie restriction reduced the number of ETS abnormalities, it did not affect the length or associated fiber atrophy of ETS abnormal regions once the abnormality was established. Thus, calorie restriction affects the onset but not the progression of electron transport system abnormalities, thereby, limiting a process that ultimately results in fiber breakage and fiber loss.

Growth hormone stimulates proliferation of old-aged regenerating liver through forkhead box m1b

The Forkhead Box (Fox) proteins are an extensive family of transcription factors that shares homology in the winged helix DNA-binding domain and the members of which play essential roles in cellular proliferation, differentiation, and longevity. Reduced cellular proliferation during aging is associated with a progressive decline in both growth hormone (GH) secretion and Foxm1b expression. Liver regeneration studies with 12-month-old (old-aged) transgenic mice indicated that increased hepatocyte expression of Foxm1b alone is sufficient to restore hepatocyte proliferation to levels found in 2-month-old (young) regenerating liver. GH therapy in older people has been shown to cause an increase in cellular proliferation, but the transcription factors that mediated this stimulation in proliferation remain uncharacterized. In this study, we showed that human GH administration to old-aged Balb/c mice dramatically increased both expression of Foxm1b and regenerating hepatocyte proliferation. This increase in old-aged regenerating hepatocyte proliferation was associated with elevated protein expression of Cdc25A, Cdc25B, and cyclin B1, with reduced protein levels of cyclin-dependent kinase inhibitor p27(Kip1) (p27). GH treatment also was found to stimulate hepatocyte proliferation and expression of Foxm1b protein without partial hepatectomy (PHx). Furthermore, GH treatment of young Foxm1b -/- mice failed to restore regenerating hepatocyte DNA replication and mitosis caused by Foxm1b deficiency. These genetic studies provided strong evidence that the presence of Foxm1b is essential for GH to stimulate regenerating hepatocyte proliferation. In conclusion, our old-aged liver regeneration studies show that increased Foxm1b levels are essential for GH to stimulate hepatocyte proliferation, thus providing a mechanism for GH action in the elderly.

Carotenoid and vitamin E status are associated with indicators of sarcopenia among older women living in the community

BACKGROUND AND AIMS

Oxidative stress may play a role in the pathogenesis of sarcopenia, and the relationship between dietary antioxidants and sarcopenia needs further elucidation. The aim was to determine whether dietary carotenoids and alpha-tocopherol are associated with sarcopenia, as indicated by low grip, hip, and knee strength.

METHODS

Cross-sectional analyses were conducted on 669 non-disabled to severely disabled community-dwelling women aged 70 to 79 who participated in the Women's Health and Aging Studies. Plasma carotenoids and alpha-tocopherol were measured. Grip, hip, and knee strength were measured, and low strength was defined as the lowest tertile of each strength measure.

RESULTS

Higher plasma concentrations of alpha-carotene, beta-carotene, beta-cryptoxanthin, and lutein/zeaxanthin were associated with reduced risk of low grip, hip, and knee strength. After adjusting for potential confounding factors such as age, race, smoking, cardiovascular disease, arthritis, and plasma interleukin-6 concentrations, there was an independent association for women in the highest compared with the lowest quartile of total carotenoids with low grip strength [Odds Ratios (OR) 0.34, 95% Confidence Interval (CI) 0.20-0.59], low hip strength (OR 0.28, 95% CI 0.16-0.48), and low knee strength (OR 0.45, 95% CI 0.27-0.75), and there was an independent association for women in the highest compared with the lowest quartile of alpha-tocopherol with low grip strength (OR 0.44, 95% CI 0.24-0.78) and low knee strength (OR 0.52, 95% CI 0.29-0.95).

CONCLUSIONS

Higher carotenoid and alpha-tocopherol status were independently associated with higher strength measures. These data support the hypothesis that oxidative stress is associated with sarcopenia in older adults, but further longitudinal and interventional studies are needed to establish causality.

Low vitamin D and high parathyroid hormone levels as determinants of loss of muscle strength and muscle mass (sarcopenia): the Longitudinal Aging Study Amsterdam

The age-related change in hormone concentrations has been hypothesized to play a role in the loss of muscle mass and muscle strength with aging, also called sarcopenia. The aim of this prospective study was to investigate whether low serum 25-hydroxyvitamin D (25-OHD) and high serum PTH concentration were associated with sarcopenia. In men and women aged 65 yr and older, participants of the Longitudinal Aging Study Amsterdam, grip strength (n = 1008) and appendicular skeletal muscle mass (n = 331, using dual-energy x-ray absorptiometry) were measured in 1995-1996 and after a 3-yr follow-up. Sarcopenia was defined as the lowest sex-specific 15th percentile of the cohort, translating into a loss of grip strength greater than 40% or a loss of muscle mass greater than 3%. After adjustment for physical activity level, season of data collection, serum creatinine concentration, chronic disease, smoking, and body mass index, persons with low (<25 nmol/liter) baseline 25-OHD levels were 2.57 (95% confidence interval 1.40-4.70, based on grip strength) and 2.14 (0.73-6.33, based on muscle mass) times more likely to experience sarcopenia, compared with those with high (>50 nmol/liter) levels. High PTH levels (>or=4.0 pmol/liter) were associated with an increased risk of sarcopenia, compared with low PTH (<3.0 pmol/liter): odds ratio = 1.71 (1.07-2.73) based on grip strength, odds ratio = 2.35 (1.05-5.28) based on muscle mass. The associations were similar in men and women. The results of this prospective, population-based study show that lower 25-OHD and higher PTH levels increase the risk of sarcopenia in older men and women.

Beta 2-agonist administration reverses muscle wasting and improves muscle function in aged rats

The beta2-adrenoceptor agonist (beta2-agonist) fenoterol has potent anabolic effects on rat skeletal muscle. We conducted an extensive dose-response study to determine the most efficacious dose of fenoterol for increasing skeletal muscle mass in adult rats and used this dose in testing the hypothesis that fenoterol may have therapeutic potential for ameliorating age-related muscle wasting and weakness. We used adult (16-month-old) rats that had completed their growth and development, and old (28-month-old) rats that exhibited characteristic muscle wasting and weakness, and treated them daily with either fenoterol (1.4 mg kg(-1), i.p), or saline vehicle, for 4 weeks. Following treatment, functional characteristics of fast-twitch extensor digitorum longus (EDL) and predominantly slow-twitch soleus muscles of the hindlimb were assessed in vitro. Untreated old rats exhibited a loss of skeletal muscle mass and a decrease in force-producing capacity, in both fast and slow muscles, compared with adult rats (P < 0.05). However, there was no age-associated decrease in skeletal muscle beta-adrenoceptor density, nor was the muscle response to chronic beta-agonist stimulation reduced with age. Thus, muscle mass and force-producing capacity of EDL and soleus muscles from old rats treated with fenoterol was equivalent to, or greater than, untreated adult rats. The increase in mass and strength was attributed to a non-selective increase in the cross-sectional area of all muscle fibre types, in both the EDL and soleus. Fenoterol treatment caused a small increase in fatiguability due to a decrease in oxidative metabolism in both EDL and soleus muscles, with some cardiac hypertrophy. Further studies are needed to fully separate the desirable effects on skeletal muscle and the undesirable effects on the heart. Nevertheless, our results demonstrate that fenoterol is a powerful anabolic agent that can restore muscle mass and strength in old rats, and provide preliminary evidence of therapeutic potential for age-related muscle wasting and weakness.

Testosterone Supplementation for Aging-Associated Sarcopenia

Aging of humans is associated with a loss of muscle mass and function, and an increase in fat mass. Epidemiologic studies have demonstrated a correlation between bioavailable testosterone concentrations and fat-free mass and muscle strength. Testosterone replacement in older men with low testosterone levels increases fat-free mass and muscle strength, and decreases fat mass. However, we do not know whether testosterone replacement improves physical function and other health-related outcomes, or reduces the risk of disability, falls, or fractures in older men with low testosterone levels. The long-term risks and benefits of testosterone supplementation in older men are not known.

Increased risk of falls and increased bone resorption in elderly men with partial androgen deficiency: the MINOS study

The goal of this study was to identify the clinical and biological patterns of hypogonadism in a cohort of 1040 elderly men. Residual androgenic activity was estimated by total testosterone as well as the apparent free testosterone concentration (AFTC) and free testosterone index (FTI) calculated on the basis of concentrations of SHBG and total testosterone using appropriate formulae. The lower limit of the normal range defined by 2 SD below the mean in 150 healthy, nonobese, and nonsmoking men, aged 19-40 yr, was calculated for total testosterone (9.26 nmol/liter), AFTC (146 pmol/liter), and FTI (0.14 nmol/nmol). The prevalence of hypogonadism increased with ageing. Hypogonadal men were older and heavier (due to a higher fat body mass) and had lower concentrations of 17 beta-estradiol and androstenedione than men with normal androgenic activity. Men with decreased AFTC had a slightly lower bone mineral density (BMD) at certain sites. Men with decreased FTI had lower appendicular skeletal muscle mass and relative skeletal muscle index. For all three measures of androgenic activity, hypogonadal men had increased levels of the markers of bone resorption. In the multiple regression models including both 17 beta-estradiol and testosterone (total, AFTC, or FTI), 17 beta-estradiol was the only significant determinant of BMD. In the multiple regression models including 17 beta-estradiol and AFTC or FTI, only testosterone was a significant determinant of the variability in bone formation markers, whereas both 17 beta-estradiol and testosterone were significant determinants of the variability of the markers of bone resorption. Hypogonadism was associated with an increase in the risk of falls, an impairment of static and dynamic balance, as well as the inability to stand up from a chair and to perform the tandem walk. Decreased AFTC (<146 pmol/liter) discriminated best men with functional disabilities (odds ratio, 1.54-7.95; P < 0.05-0.0001). Hypogonadal elderly men had increased bone resorption that was not adequately matched by an increase in bone formation, lower muscle strength, impaired static and dynamic balance, a higher risk of falls, and, in men with low AFTC, a slightly lower BMD. Low AFTC seems to have the best discriminative power for densitometric, biochemical, and functional parameters, followed by FTI, whereas total testosterone was the least discriminative. In multiple regression models, 17 beta-estradiol was the strongest determinant of BMD, and AFTC and FTI were significant determinants of the variability in bone formation markers, whereas both 17 beta-estradiol and testosterone determined the variability in bone resorption markers.

Dynamics of Postdenervation Atrophy of Young and Old Skeletal Muscles: Differential Responses of Fiber Types and Muscle Types

We investigated the dynamics of muscle fiber atrophy in denervated fast and slow muscles of young and old rats. Hind limbs of 4-month-old and 24-month-old male rats were denervated, and soleus and tibialis anterior muscles were examined morphometrically 1 and 2 months after denervation. In all denervated muscles, type II muscle fibers underwent rapid atrophy, although muscle-specific differences in rate were observed. In both young and old denervated soleus muscles, the type I fibers underwent a pattern of atrophy closely paralleling that of the type II fibers, but in the tibialis anterior muscle, the mean cross-sectional area of the type I fibers actually increased during the first 2 months postdenervation. This study has shown that, among different muscles and between young and old rats, there is considerable variation in the response of the muscle fibers to denervation and that one cannot generalize from one muscle or one age to another.

Invited review: Aging and sarcopenia

Aging is associated with progressive loss of neuromuscular function that often leads to progressive disability and loss of independence. The term sarcopenia is now commonly used to describe the loss of skeletal muscle mass and strength that occurs in concert with biological aging. By the seventh and eighth decade of life, maximal voluntary contractile strength is decreased, on average, by 20-40% for both men and women in proximal and distal muscles. Although age-associated decreases in strength per unit muscle mass, or muscle quality, may play a role, the majority of strength loss can be accounted for by decreased muscle mass. Multiple factors lead to the development of sarcopenia and the associated impact on function. Loss of skeletal muscle fibers secondary to decreased numbers of motoneurons appears to be a major contributing influence, but other factors, including decreased physical activity, altered hormonal status, decreased total caloric and protein intake, inflammatory mediators, and factors leading to altered protein synthesis, must also be considered. The prevalence of sarcopenia, which may be as high as 30% for those >/=60 yr, will increase as the percentage of the very old continues to grow in our populations. The link between sarcopenia and disability among elderly men and women highlights the need for continued research into the development of the most effective interventions to prevent or at least partially reverse sarcopenia, including the role of resistance exercise and other novel pharmacological and nutritional interventions.