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In the present article, the rationale that guided the operationalization of the theoretical concept of physical frailty and sarcopenia (PFS), the condition of interest for the "Sarcopenia and Physical Frailty in Older People: Multicomponent Treatment Strategies" (SPRINTT) trial, is presented. In particular, the decisions lead to the choice of the adopted instruments, and the reasons for setting the relevant thresholds are explained. In SPRINTT, the concept of physical frailty is translated with a Short Physical Performance Battery score of ≥3 and ≤9. Concurrently, sarcopenia is defined according to the recent definitions of low muscle mass proposed by the Foundation for the National Institutes of Health-Sarcopenia Project. Given the preventive purpose of SPRINTT, older persons with mobility disability (operationalized as incapacity to complete a 400-m walk test within 15 min; primary outcome of the trial) at the baseline are not included within the diagnostic spectrum of PFS.

This study evaluates the prevalence of sarcopenia among older people admitted to a rehabilitation unit after hip fracture and the association between sarcopenia and functional outcomes. The results show that sarcopenia had a negative impact on functional recovery. The assessment of sarcopenia among older adults receiving rehabilitation programs is crucial. Sarcopenia is a highly prevalent geriatric syndrome associated with adverse outcomes, including falls, disability, institutionalization, and mortality. Few studies assessed sarcopenia among older adults receiving rehabilitation programs. Patients aged 70 years or more consecutively admitted to in-hospital rehabilitation programs that had suffered from hip fracture entered the study. Sarcopenia was defined according to the Foundation for National Institutes of Health (FNIH) criteria. Multivariable linear regression models were used to analyze the association between the sarcopenia and functional recovery. The recruited population was composed of 127 patients, with a mean age of 81.3 ± 4.8 years, predominantly females (64.6%). Using the criteria proposed by the FNIH, patients with a diagnosis of sarcopenia were 43 (33.9%). After adjustment for potential confounders, participants with sarcopenia had a significant increased risk of incomplete functional recovery compared with non-sarcopenic patients (OR 3.07, 95% CI 1.07–8.75). Compared with participants without sarcopenia, those with sarcopenia showed lower Barthel index scores at the time of discharge from the rehabilitation unit (69.2 versus 58.9, respectively; p

Osteoporosis is a condition featured by bone mass loss and bone tissue microarchitectural alterations due to impaired tissue homeostasis favoring excessive bone resorption versus deposition. The trigger of such an impairment and the downstream molecular pathways involved are yet to be clarified. The natural course of osteoporosis is particularly worrisome because, through a “silent” progression, it enhances bone fragility, increases the risk of fractures and is associated with increased risk of disability and mortality. To date, the assessment of bone mineral density by dual-energy X-ray absorptiometry, represents the non-invasive gold standard for the evaluation of bone mineralization and the diagnosis of osteoporosis. Although long known as a condition merely related to the hormonal-driven loss of bone homeostasis, emerging evidence supports the need of reframing osteoporosis in the context of structural and functional changes of the musculoskeletal system as a whole. Several age-related alterations of bone microenvironment and an altered bone-muscle crosstalk have been suggested to be relevant contributors to loss of bone strength and mass characterizing osteoporosis. The present work provides an overview of the current knowledge of the pathophysiology of osteoporosis obtained through advances in epigenetics, cell biology and osteoimmunology. In light of the increasingly recognized importance of bone-muscle interconnection, this review also discusses relevant pathways that may be dissected for identifying new therapeutic targets for age-related musculoskeletal degeneration.

Sarcopenia encompasses the loss of muscle mass and strength/function during aging. Several methods are available for the estimation of muscle or lean body mass. Popular assessment tools include body imaging techniques (e.g., magnetic resonance imaging, computed tomography, dual X-ray absorptiometry, ultrasonography), bioelectric impedance analysis, anthropometric parameters (e.g., calf circumference, mid-arm muscle circumference), and biochemical markers (total or partial body potassium, serum and urinary creatinine, deuterated creatine dilution method). The heterogeneity of the populations to be evaluated as well as the setting in which sarcopenia is investigated impacts the definition of "gold standard" assessment techniques. The aim of this article is to critically review available methods for muscle mass estimation, highlighting strengths and weaknesses of each of them as well as their proposed field of application.

We previously reported the ability of dietary supplementation with acetyl-l-carnitine (ALCAR) to prevent age-related decreases of mitochondrial biogenesis in skeletal muscle and liver of old rats. Here, we investigate the effects of ALCAR supplementation in cerebral hemispheres and cerebellum of old rats by analyzing several parameters linked to mitochondrial biogenesis, mitochondrial dynamics and antioxidant defenses. We measured the level of the coactivators PGC-1α and PGC-1β and of the factors regulating mitochondrial biogenesis, finding an age-related decrease of PGC-1β, whereas PGC-1α level was unvaried. Twenty eight-month old rats supplemented with ALCAR for one and two months showed increased levels of both factors. Accordingly, the expression of the two transcription factors NRF-1 and TFAM followed the same trend of PGC-1β. The level of mtDNA, ND1 and the activity of citrate synthase, were decreased with aging and increased following ALCAR treatment. Furthermore, ALCAR counteracted the age-related increase of deleted mtDNA. We also analyzed the content of proteins involved in mitochondrial dynamics (Drp1, Fis1, OPA1 and MNF2) and found an age-dependent increase of MFN2 and of the long form of OPA1. ALCAR treatment restored the content of the two proteins to the level of the young rats. No changes with aging and ALCAR were observed for Drp1 and Fis1. ALCAR reduced total cellular levels of oxidized PRXs and counteracted the age-related decrease of PRX3 and SOD2. Overall, our findings indicate a systemic positive effect of ALCAR dietary treatment and a tissue specific regulation of mitochondrial homeostasis in brain of old rats. Moreover, it appears that ALCAR acts as a nutrient since in most cases its effects were almost completely abolished one month after treatment suspension. Dietary supplementation of old rats with this compound seems a valuable approach to prevent age-related mitochondrial dysfunction and might ultimately represent a strategy to delay age-associated negative consequences in mitochondrial homeostasis.

The exploration of frailty as a pre-disability geriatric condition represents one of the most promising research arenas of modern medicine. Frailty is today indicated as a paradigmatic condition around which the traditional healthcare systems might be re-shaped and optimized in order to address the complexities and peculiarities of elders. Unfortunately, the lack of consensus around a single operational definition has limited the clinical implementation of frailty in clinical practice. In these last years, growing attention (even beyond the traditional boundaries of geriatric medicine) has been given to physical performance measures. These instruments have shown to be predictive of negative health-related events and able to support an accurate estimation of the "biological age" in late life. The strong construct of physical performance measures also makes them particularly suitable for the assessment of the frailty status. Furthermore, the adoption of physical performance measures may help render the frailty condition more organ-specific (i.e., centred on the skeletal muscle quality) and less heterogeneous than currently perceived. The translation of the frailty concept by means of physical performance measures implicitly represents an attempt to go beyond traditional paradigms. In this context, the recently funded "Sarcopenia and Physical fRailty IN older people: multi-componenT Treatment strategies" (SPRINTT) project (largely based on such a novel approach) may indeed fill an important gap in the field and provide key insights for counteracting the disabling cascade in the elderly.

Physical frailty (PF) and sarcopenia are major health issues in geriatric populations, given their high prevalence and association with several adverse outcomes. Nevertheless, the lack of an univocal operational definition for the two conditions has so far hampered their clinical implementation. Existing definitional ambiguities of PF and sarcopenia, together with their complex underlying pathophysiology, also account for the absence of robust biomarkers that can be used for screening, diagnostic and/or prognostication purposes. This review provides an overview of currently available biological markers for PF and sarcopenia, as well as a critical appraisal of strengths and weaknesses of traditional procedures for biomarker development in the field. A novel approach for biomarker identification and validation, based on multivariate methodologies, is also discussed. This strategy relies on the multidimensional modeling of complementary biomarkers to cope with the phenotypical and pathophysiological complexity of PF and sarcopenia. Biomarkers identified through the implementation of multivariate strategies may be used to support the detection of the two conditions, track their progression over time or in response to interventions, and reveal the onset of complications (e.g., mobility disability) at a very early stage.

Objectives Declining muscle mass and function are hallmarks of the aging process. The preservation of muscle trophism may protect against various negative health outcomes. Age- and sex-specific curves of muscle mass, strength, and function, using data from a large sample of community-dwelling people, are necessary. Material and methods Two surveys (Longevity Check-up and Very Important Protein [VIP]), conducted during EXPO 2015 in Milan, consisted of a population assessment aimed at evaluating the prevalence of specific health metrics in subjects outside of a research setting (n = 3206), with a special focus on muscle mass, strength, and function. Muscle mass was estimated by using mid-arm muscle circumference (MAMC) and calf circumference of the dominant side. Muscle strength and function were assessed through handgrip strength testing and repeated chair stand test, respectively. Results The mean age of 3206 participants in the Longevity Check-up and VIP surveys was 51.9 years (SD 15.6, range 18–98 years), and 1694 (52.8%) were women. Cross-sectional inspection suggests that both calf circumference and MAMC decline nonlinearly with age and the rate of decline varies by gender. These measures are stable until 50 years and then begin to decrease slightly with age, with the effect being more evident in men than in women. The main effect of the age category was observed in muscle strength and physical performance parameters. Muscle strength declined significantly after 45 years of age, both in men and women (P

The sustainability of health and social care systems is threatened by a growing population of older persons with heterogeneous needs related to multimorbidity, frailty, and increased risk of functional impairment. Since disability is difficult to reverse in old age and is extremely burdensome for individuals and society, novel strategies should be devised to preserve adequate levels of function and independence in late life. The development of mobility disability, an early event in the disablement process, precedes and predicts more severe forms of inability. Its prevention is, therefore, critical to impede the transition to overt disability. For this reason, the Sarcopenia and Physical fRailty IN older people: multi-componenT Treatment strategies (SPRINTT) project is conducting a randomized controlled trial (RCT) to test a multicomponent intervention (MCI) specifically designed to prevent mobility disability in high-risk older persons. SPRINTT is a phase III, multicenter RCT aimed at comparing the efficacy of a MCI, based on long-term structured physical activity, nutritional counseling/dietary intervention, and an information and communication technology intervention, versus a healthy aging lifestyle education program designed to prevent mobility disability in 1500 older persons with physical frailty and sarcopenia who will be followed for up to 36 months. The primary outcome of the SPRINTT trial is mobility disability, operationalized as the inability to walk for 400 m within 15 min, without sitting, help of another person, or the use of a walker. Secondary outcomes include changes in muscle mass and strength, persistent mobility disability, falls and injurious falls, disability in activities of daily living, nutritional status, cognition, mood, the use of healthcare resources, cost-effectiveness analysis, quality of life, and mortality rate. SPRINTT results are expected to promote significant advancements in the management of frail older persons at high risk of disability from both clinical and regulatory perspectives. The findings are also projected to pave the way for major investments in the field of disability prevention in old age.

Aging is accompanied by a progressive increase in the incidence and prevalence of cardiovascular disease (CVD). Prolonged exposure to cardiovascular risk factors, together with intrinsic age-dependent declines in cardiac functionality, increases the vulnerability of the heart to both endogenous and exogenous stressors, ultimately enhancing the susceptibility to developing CVD in late life. Both increased levels of oxidative damage and the accumulation of dysfunctional mitochondria have been observed in a wide range of cardiac diseases, which may therefore represent a common ground upon which many aspects of CVD develop. In this review, we summarize the current knowledge on the mechanisms whereby oxidative stress arising from mitochondrial dysfunction is involved in the process of cardiac aging and in the pathogenesis of CVD highly prevalent in late life (e.g., heart failure and ischemic heart disease). Special emphasis is placed on recent evidence about the role played by alterations in cellular quality control systems, in particular autophagy/mitophagy and mitochondrial dynamics (fusion and fission), and their interconnections in the context of age-related CVD. Cardioprotective interventions acting through the modulation of mitochondrial autophagy (calorie restriction, calorie restriction mimetics, and the gasotransmitter hydrogen sulfide) are also presented. This article is part of a Special Issue entitled "Protein Quality Control, the Ubiquitin Proteasome System, and Autophagy". © 2014 Elsevier Ltd.

Frailty encompasses several domains (i.e., metabolic, physical, cognitive). The multisystem derangements underlying frailty pathophysiology, its phenotypic heterogeneity, and the fluctuations of individuals across severity states have hampered a comprehensive appraisal of the condition. Circulating biomarkers emerged as an alleged tool for capturing this complexity and, as proxies for organismal metabolic changes, may hold the advantages of: 1) supporting diagnosis, 2) tracking the progression, 3) assisting healthcare professionals in clinical and therapeutic decision-making, and 4) verifying the efficacy of an intervention before measurable clinical manifestations occur. Among available analytical tools, metabolomics are able to identify and quantify the (ideally) whole repertoire of small molecules in biological matrices (i.e., cells, tissues, and biological fluids). Results of metabolomics analysis may define the final output of genome-environment interactions at the individual level. This entire collection of metabolites is called “metabolome” and is highly dynamic. Here, we discuss how monitoring the dynamics of metabolic profiles may provide a read-out of the environmental and clinical disturbances affecting cell homeostasis in frailty-associated conditions.

The progressive decline of cell function and integrity, manifesting clinically as increased vulnerability to adverse outcomes and death, is core to biological aging. Mitochondrial dysfunction, oxidative stress, altered intercellular communication (including chronic low-grade inflammation), genomic instability, telomere attrition, loss of proteostasis, altered nutrient sensing, epigenetic alterations, and stem cell exhaustion have been proposed as hallmarks of aging. These “aging pillars„ are not mutually exclusive, making the matter intricate and leaving numerous unanswered questions. The characterization of circulating extracellular vesicles (EVs) has recently allowed specific secretory phenotypes associated with aging to be identified. As such, EVs may serve as novel biomarkers for capturing the complexity of aging. Besides the mitochondrial⁻lysosomal axis, EV trafficking has been proposed as an additional layer in mitochondrial quality control. Indeed, disruption of the mitochondrial⁻lysosomal axis coupled with abnormal EV secretion may play a role in the pathogenesis of aging and several disease conditions. Here, we discuss (1) the mechanisms of EV generation; (2) the relationship between the mitochondrial⁻lysosomal axis and EV trafficking in the setting of mitochondrial quality control; and (3) the prospect of using EVs as aging biomarkers and as delivery systems for therapeutics against age-related conditions.

Muscle loss during aging and disuse is a highly prevalent and disabling condition, but knowledge about cellular pathways mediating muscle atrophy is still limited. Given the postmitotic nature of skeletal myocytes, the maintenance of cellular homeostasis relies on the efficiency of cellular quality control mechanisms. In this scenario, alterations in mitochondrial function are considered a major factor underlying sarcopenia and muscle atrophy. Damaged mitochondria are not only less bioenergetically efficient, but also generate increased amounts of reactive oxygen species, interfere with cellular quality control mechanisms, and display a greater propensity to trigger apoptosis. Thus, mitochondria stand at the crossroad of signaling pathways that regulate skeletal myocyte function and viability. Studies on these pathways have sometimes provided unexpected and counterintuitive results, which suggests that they are organized into a complex, heterarchical network that is currently insufficiently understood. Untangling the complexity of such a network will likely provide clinicians with novel and highly effective therapeutics to counter the muscle loss associated with aging and disuse. In this review, we summarize the current knowledge on the mechanisms whereby mitochondrial dysfunction intervenes in the pathogenesis of sarcopenia and disuse atrophy, and highlight the prospect of targeting specific processes to treat these conditions.

Sarcopenia, the loss of skeletal muscle mass and function that occurs with aging, is associated withincreased risk for several adverse health outcomes, including frailty, disability, falls, loss of independent living,and mortality. At present, no pharmacological treatment exists that is able to definitely halt the progression ofsarcopenia. Likewise, no pharmacological remedies are yet available to prevent the onset of age-related musclewasting. The combination of nutritional interventions and physical exercise appears to be the most effectivestrategy presently available for the management of sarcopenia. The purposes of this review are to summarize thecurrent knowledge on the role of nutrition as a countermeasure for sarcopenia, illustrate the mechanisms of actionof relevant dietary agents on the aging muscle, and introduce novel nutritional strategies that may help preservemuscle mass and function into old age. Issues related to the identification of the optimal timing of nutritionalinterventions in the context of primary and secondary prevention are also discussed. Finally, the prospect ofelaborating personalized dietary and physical exercise recommendations through the implementation ofintegrated, high-throughput analytic approaches is illustrated.

Sarcopenia, the progressive and generalized loss of muscle mass and strength/function, is a major health issue in older adults, given its high prevalence and burdensome clinical ramifications. The absence of a unified operational definition for sarcopenia has hampered its full appreciation by healthcare providers, researchers and policy-makers. At the same time, this unresolved debate and the complexity of musculoskeletal aging pose major challenges to the identification of clinically meaningful biomarkers. This review summarizes the current knowledge on biological markers for sarcopenia, including a critical appraisal of traditional procedures for biomarker development in the field of muscle aging. As an alternative approach, we illustrate the potential advantages of biomarker discovery procedures based on multivariate methodologies. Relevant examples of multidimensional biomarker modeling are provided with an emphasis on its clinical and research application.

Sarcopenia, the progressive and generalized loss of skeletal muscle mass and strength/function associated with aging, increases the risk of a vast array of adverse health outcomes, including falls, morbidity, loss of independence, disability, and mortality. As such, sarcopenia poses a huge socioeconomic burden in developed countries. The development and implementation of effective interventions against sarcopenia are therefore a public health priority. A preliminary, fundamental step in such a process entails the agreement of researchers, healthcare professionals and policymakers around a unique operational definition of sarcopenia. This will facilitate the framing of a clear clinical entity to be incorporated in standard practice, the understanding of the underlying pathophysiology, and the identification of biological targets for drug development.

The identification of cost-effective interventions that improve the health status and prevent disability in old age is one of the most important public health challenges. Regular physical activity is the only intervention that has consistently been shown to improve functional health and energy balance and to reduce the risk of cardiovascular disease, stroke, diabetes, several cancers, depression and falls. In advanced age, physical activity is also effective at mitigating sarcopenia, restoring robustness, and preventing/delaying the development of disability. On the other hand, physical inactivity is recognized as one of the leading causes of several chronic degenerative diseases and is also a major contributing factor to sarcopenia and functional disability. This compelling evidence has prompted the World Health Organization to recommend engaging in regular physical activity throughout one's life course. The present review summarizes the available evidence in support of physical activity as a remedy against physical frailty and sarcopenia. The relevant pathways through which the benefits of physical activity are conveyed are also discussed.

The provision of sufficient amounts of dietary proteins is central to muscle health as it ensures the supply of essential amino acids and stimulates protein synthesis. Older persons, in particular, are at high risk of insufficient protein ingestion. Furthermore, the current recommended dietary allowance for protein (0.8 g/kg/day) might be inadequate for maintaining muscle health in older adults, probably as a consequence of “anabolic resistance” in aged muscle. Older individuals therefore need to ingest a greater quantity of protein to maintain muscle function. The quality of protein ingested is also essential to promoting muscle health. Given the role of leucine as the master dietary regulator of muscle protein turnover, the ingestion of protein sources enriched with this essential amino acid, or its metabolite β-hydroxy β-methylbutyrate, is thought to offer the greatest benefit in terms of preservation of muscle mass and function in old age.

Background: The C-terminal agrin fragment (CAF), a circulating byproduct of neuromuscular junction disassembly, has been proposed as a possible biomarker for sarcopenia. However, its validity in "real-world", multimorbid older persons is currently unknown. The present study was undertaken to verify if serum CAF levels were associated with sarcopenia in a population of old and very old persons living in the community. Methods: Data were from the ilSIRENTE Aging and Longevity Study, a prospective cohort study conducted in all persons aged 80years and older residing in the Sirente geographic area (Italy; n=332). The identification of sarcopenia was based on the criteria elaborated by the European Working Group on Sarcopenia in Older People (EWGSOP). Serum levels of CAF were determined using a commercial ELISA kit. Results: Sarcopenia was identified in 101 participants (30.8%). Serum levels of CAF were significantly higher in older adults with sarcopenia compared with non-sarcopenic participants (96.99±5.40pmol/L vs. 76.54±2.15pmol/L; p

Sarcopenia, the age-dependent loss of muscle mass and function, is a common condition among older adults, and is associated with several adverse health outcomes. Owing to the impact of sarcopenia on quality of life, disability and mortality, a greater awareness is necessary in order to correctly identify the condition both in community and geriatric settings. Research on sarcopenia prevention and treatment is developing quickly, but many questions are still unanswered. The core of the sarcopenia condition involves quantitative and qualitative losses of skeletal muscle. These two dimensions should therefore be considered when designing and testing preventive and therapeutic interventions. The recently released operationalization of sarcopenia by the Foundation for the National Institutes of Health (FNIH) Sarcopenia Project allows for the framing of an objective, standardized, and clinically relevant condition, which should facilitate its translation into the clinical arena as well as its adoption by public health and regulatory agencies. Such a conceptualization might eventually encourage key stakeholders to combine their efforts in approaching the sarcopenia condition. Bearing these considerations in mind, the "Sarcopenia and Physical fRailty IN older people: multi-componenT Treatment strategies" project has operationalized a specific condition, named physical frailty and sarcopenia (PF&S), characterized by the combination of low physical performance (based on the Short Physical Performance Battery) and low muscle mass (according to the FNIH cut-points). A randomized controlled trial will be conducted to evaluate the efficacy of a multi-component intervention for preventing mobility disability and other adverse health outcomes in older adults with PF&S.

Advancing age is associated with changes in dietary behaviors that promote the development of sarcopenia and physical frailty. These two conditions, in turn, are major risk factors for several adverse health-related events, including disability, loss of independence, institutionalization, and mortality. Growing evidence indicates that the ingestion of adequate amounts of calories, protein, vitamin D, and omega-3 fatty acids may represent an effective countermeasure to sarcopenia and physical frailty. Supplementation with specific nutrients is advisable in older persons engaged in physical exercise programs. This chapter provides an overview of current dietary recommendations for the management of sarcopenia and physical frailty and highlights the therapeutic benefits that may be achieved via targeted nutrient supplementation.

The prevalence of cardiovascular disease increases with advancing age. Although long-term exposure to cardiovascular risk factors plays a major role in the etiopathogenesis of cardiovascular disease, intrinsic cardiac aging enhances the susceptibility to developing heart pathologies in late life. The progressive decline of cardiomyocyte mitochondrial function is considered a major mechanism underlying heart senescence. Damaged mitochondria not only produce less ATP but also generate increased amounts of reactive oxygen species and display a greater propensity to trigger apoptosis. Given the postmitotic nature of cardiomyocytes, the efficient removal of dysfunctional mitochondria is critical for the maintenance of cell homeostasis, because damaged organelles cannot be diluted by cell proliferation. The only known mechanism whereby mitochondria are turned over is through macroautophagy. The efficiency of this process declines with advancing age, which may play a critical role in heart senescence and age-related cardiovascular disease. The present review illustrates the putative mechanisms whereby alterations in the autophagic removal of damaged mitochondria intervene in the process of cardiac aging and in the pathogenesis of specific heart diseases that are especially prevalent in late life (eg, left ventricular hypertrophy, ischemic heart disease, heart failure, and diabetic cardiomyopathy). Interventions proposed to counteract cardiac aging through improvements in macroautophagy (eg, calorie restriction and calorie restriction mimetics) are also presented.

In the literature, different criteria have been validated to identify frail older subjects, which mainly refer to two conceptual models: the cumulative deficit approach proposed by Rockwood and the Physical Frailty (PF) phenotype proposed by Fried. Both models have received empirical validation. Nevertheless, the frailty phenotype is the most widely used and presents a characterized pathophysiologic background. The PF condition depicted by the frailty phenotype has shown to be predictive of major negative health-related outcomes, including mobility disability, disability for activities of daily living, institutionalization, and mortality. At the same time, it cannot be ignored that the PF phenotype presents substantial overlaps with sarcopenia, "a syndrome characterized by progressive and generalized loss of skeletal muscle mass and strength with a risk of adverse outcomes such as physical disability, poor quality of life and death". In fact, many of the adverse outcomes of frailty are probably mediated by sarcopenia. Therefore, sarcopenia may be considered both as the biological substrate for the development of PF and the pathway through which the negative health outcomes of frailty ensue. Although PF encompasses only a part of the frailty spectrum, the identification of a definite biological basis (i.e., skeletal muscle decline) opens new venues for the development of interventions to slow or reverse the progression of this condition. Here, we present a novel conceptualisation of PF which will possibly promote significant advancements over the traditional approaches to this syndrome by enabling the precise operationalisation of the condition, a clear identification of the affected population and the rapid translation of findings to the clinical arena.

Physical frailty and sarcopenia are two common and largely overlapping geriatric conditions upstream of the disabling cascade. The lack of a unique operational definition for physical frailty and sarcopenia and the complex underlying pathophysiology make the development of biomarkers for these conditions extremely challenging. Indeed, the current definitional ambiguities of physical frailty and sarcopenia, together with their heterogeneous clinical manifestations, impact the accuracy, specificity, and sensitivity of individual biomarkers proposed so far. In this review, the current state of the art in the development of biomarkers for physical frailty and sarcopenia is presented. A novel approach for biomarker identification and validation is also introduced that moves from the 'one fits all' paradigm to a multivariate methodology. peerReviewed

Background: Sarcopenia, the age-related loss of muscle mass and function, represents a relevant public health issue due to its high prevalence and detrimental consequences. While the exact mechanisms underlying the pathogenesis of sarcopenia are not clear, growing experimental evidence indicates that progressive myonuclear elimination over the course of aging via an apoptosis-like process may represent a converging mechanism through which muscle atrophy and loss of physical function develop. Notably, the proapoptotic environment taking place in aged muscle appears amenable to interventions. Objective: We aimed at providing (1) an overview of signaling pathways of apoptosis relevant to sarcopenia, and (2) a review of the literature supporting myocyte apoptosis as a target for interventions against muscle aging. Methods: We summarized findings from studies focused on skeletal myocyte apoptosis as a mechanism in the development of sarcopenia and reports supporting myonuclear apoptosis as a target for interventions against age-related muscle loss. Results: Advanced age is associated with increased signaling through extrinsic and intrinsic apoptotic pathways in skeletal myocytes. In contrast, downregulation of myocyte apoptosis through calorie restriction, exercise training, hormonal supplementation, drugs (e.g. angiotensin-converting enzyme inhibitors, acetaminophen, antimyostatin antibodies), nutraceuticals or genetic interventions (e.g. PGC-1α overexpression) is linked with preservation of muscle integrity and improved physical performance in late life. Preliminary data also indicate that skeletal myocyte apoptotic signaling may be downregulated by compounds, such as resveratrol, with calorie restriction-mimicking properties. Whether exercise mimetics exert a similar effect has not yet been investigated. Conclusions: Available evidence suggests that targeting myonuclear apoptosis might provide novel and effective therapeutic tools to combat sarcopenia. Further research is required to definitely establish if downregulating myonuclear apoptosis is effective in maintaining muscle mass and function in late life, identify the most relevant apoptotic pathway(s) to target, and determine the optimal timing for intervening.

Obesity is one of the most burdensome health issues of our time. According to a 2012 World Health Organization report, there are more than 1.4 billion overweight adults worldwide, of whom ∼500 million are obese (1). Strikingly, 40 million children under the age of 5 are currently overweight or obese (1). These statistics are especially alarming because of the long list of obesity-associated conditions. These include insulin resistance, type 2 diabetes, dyslipidemia, cardiovascular disease, and several cancers (2). Among the consequences of the obesity epidemic are an expanding population of chronically ill people, escalating health care expenses, and the prediction that, for the first time in human history, the current generation will have a shorter life span than the previous one (3). Accumulation of fat results from a prolonged imbalance between energy intake and energy expenditure. One might think that reducing fat mass in obese individuals could be achieved relatively simply by either decreasing food consumption or increasing energy expenditure, thereby attaining a sustained negative energy balance. Unfortunately, this task is not easy to achieve, in large part because of the combination of sedentary lifestyle and the availability of calorie-dense, inexpensive food. With the exception of bariatric surgery (4), most antiobesity interventions that target energy intake result in moderate, and often temporary, weight loss. Sadly, pharmacological strategies aimed at increasing energy expenditure have not delivered on the promise of efficacy or safety when translated from animal models to humans. For instance, supraphysiologic doses of thyroid …

Obesity is a complex multifactorial disease involving genetic and environmental factors and influencing several different metabolic pathways. In this regard, metabonomics, that is the study of complex metabolite profiles in biological samples, may provide a systems approach to understand the global metabolic regulation of the organism in relation to this peculiar pathology. In this pilot study, we have applied a nuclear magnetic resonance (NMR)-based metabolomic approach on urinary samples of morbidly obese subjects. Urine samples of 15 morbidly obese insulin-resistant (body mass index>40; homeostasis assessment model of insulin resistance>3) male patients and 10 age-matched controls were collected, frozen and analyzed by high-resolution (1)H-NMR spectroscopy combined with partial least squares-discriminant analysis. Furthermore, two obese patients who underwent bariatric surgery (biliopancreatic diversion and gastric bypass, respectively) were monitored during the first 3 months after surgery and their urinary metabolic profiles were characterized. NMR-based metabolomic analysis allowed us to identify an obesity-associated metabolic phenotype (metabotype) that differs from that of lean controls. Gut flora-derived metabolites such as hippuric acid, trigonelline, 2-hydroxyisobutyrate and xanthine contributed most to the classification model and were responsible for the discrimination. These preliminary results confirmed that in humans the gut microflora metabolism is strongly linked to the obesity phenotype. Moreover, the typical obese metabotype is lost after weight loss induced by bariatric surgery.

Sarcopenia is the loss of skeletal muscle mass and function that occurs with aging. This condition is associated with increased risk for several adverse health outcomes, including frailty, disability, falls, loss of independent living, and mortality. As yet, no pharmacological treatment exists to halt the progression of sarcopenia; similarly, no pharmacological remedies are available to prevent its onset. The combination of nutritional interventions and physical exercise is currently considered to be the most effective strategy for the management of sarcopenia. In this chapter, the role of nutrition as a countermeasure for sarcopenia is discussed. The chapter is organized into three main sections: established dietary recommendations, novel nutritional candidates, and possible dietary strategies. We conclude with presenting issues related to inappropriate prescription of nutritional supplements, and the prospect of adopting cutting-edge technologies to design targeted dietary interventions.

The presence of sarcopenia is not only rapidly rising in geriatric clinical practice and research, but is also becoming a significant concept in numerous medical specialties. This rapidly rising concept has encouraged the need to identify methods for treating sarcopenia. Physical activity measures using resistance training exercise, combined with nutritional interventions (protein and amino acid supplementation) have shown to significantly improve muscle mass and strength in older persons. Moreover, resistance training may improve muscle strength and mass by improving protein synthesis in skeletal muscle cells. Aerobic exercise has also shown to hold beneficial impacts on sarcopenia by improving insulin sensitivity. At the moment, the literature indicates that most significant improvement in sarcopenia is based on exercise programs. Thus, this type of intervention should be implemented in a persistent manner over time in elders, with or at risk of muscle loss. At the same time, physical training exercise should include correcting nutritional deficits with supplementation methods. For example, in older sarcopenic patients with adequate renal function, daily protein intake should be increased to >1. 0 grams of protein per kilogram of body weight. In particular, leucine, - hydroxy β-methylbutyrate (HMB), creatine and some milk-based proteins have been shown to improve skeletal muscle protein balance. In addition, it is also recommended for adjustment of for vitamin D deficiency, if present, considering the crucial role of vitamin D in the skeletal muscle. In this review, we provide evidence regarding the effects of different physical exercise protocols, specific nutritional intervention, and some new metabolic agents (HMB, citrulline malate, ornithine, and others) on clinical outcomes related to sarcopenia in older adults.

Mitochondrial dysfunction has been involved in muscle wasting associated with cancer cachexia (CC). Whether mitochondrial quality control (MQC) is altered in skeletal myocytes during CC is still unclear. The present investigation sought to preliminarily characterize MQC pathways in muscle of gastric cancer patients with cachexia. The study followed a case-control cross-sectional design. Intraoperative biopsies of the rectus abdominis muscle were obtained from 18 old patients with gastric adenocarcinoma (nine with CC and nine non-cachectic) and nine controls, and assayed for the expression of a set of MQC mediators. Mitofusin 2 (Mfn2) expression was reduced in cancer patients compared with controls, independent of CC, while fission protein 1 (Fis1) was up-regulated in CC patients relative to the other groups. As a result, the “fusion index” (Mfn2/Fis1 ratio) was lower in patients with CC. The mitophagy regulators PTEN-induced putative kinase 1 and Parkin were down-regulated in cancer patients compared with controls. The ratio between the protein content of the lipidated and non-lipidated forms of microtubule-associated protein 1 light chain 3B was lower in CC patients relative to controls and non-cachectic cancer patients. Finally, the expression of autophagy-associated protein 7, lysosome-associated membrane protein 2, peroxisome proliferator-activated receptor-γ coactivator-1α, and mitochondrial transcription factor A was unvarying among groups. In gastric cancer patients, cachexia is associated with derangements of the muscular MQC axis at several checkpoints: mitochondrial dynamics, mitochondrial tagging for disposal, and mitophagy signaling. Further investigations are needed to corroborate these preliminary findings and determine whether MQC pathways they may be targeted for interventions.

Among the complex determinants of aging, mitochondrial dysfunction has been in the spotlight for a long time. As the hub for many cellular functions, the maintenance of an adequate pool of functional mitochondria is crucial for tissue homeostasis. Their unique role in energy supply makes these organelles essential, especially in those tissues strictly dependent on oxidative metabolism. Mitochondrial quality control (MQC) is ensured by pathways related to protein folding and degradation as well as by processes involving the entire organelle, such as biogenesis, dynamics, and mitophagy. Dysfunctional MQC, oxidative stress and inflammation are hallmarks of senescence and chronic degenerative diseases. One of the consequences of age-related failing MQC and oxidative stress is the release of mitochondria-derived damage-associated molecular patterns (DAMPs). Through their bacterial ancestry, these molecules contribute to mounting an inflammatory response by interacting with receptors similar to those involved in pathogen-associated responses. Mitochondrial DAMPs, especially cell-free mitochondrial DNA, have recently become the subject of intensive research because of their possible involvement in conditions associated with inflammation, such as aging and degenerative diseases. Here, we review the contribution of mitochondrial DAMPs to inflammation and discuss some of the mechanisms at the basis of their generation.

Background: Failure to meet an adequate dietary intake is involved in the pathogenesis of sarcopenia and osteoporosis, which in turn increase the risk for falls and fractures, respectively. Older people with hip fracture are often protein-malnourished at hospitalization. Whether low protein-energy intake is associated with muscle atrophy in hip-fractured patients is presently unknown. This information is necessary for the development of novel strategies to manage this especially vulnerable patient population. The aim of this study was, therefore, to explore the relationship between dietary intake and muscle mass in older hip-fractured patients. Methods: Analyses were conducted in hip-fractured elderly admitted to an orthopedic and trauma surgery ward (University Hospital). Muscle mass was estimated by bioelectrical impedance analysis within 24 h from admission. Dietary information was collected via 24-h dietary recall and nutrient intake calculated by a nutrition software. Results: Among 62 hip-fractured patients (mean age 84.6 ± 7.6 years, 84% women), the average energy intake was 929.2 ± 170.3 Kcal day−1, with higher values reported by men (1.046.8 ± 231.4 Kcal day−1) relative to women (906.5 ± 148.3 Kcal day−1; p = 0.01). Absolute and normalized protein intake was 50.0 ± 13.5 g day−1 and 0.88 ± 0.27 g kg (body weight)–1 day–1, respectively, with no gender differences. A positive correlation was determined between total energy intake and muscle mass (r = 0.384; p = 0.003). Similarly, protein and leucine consumption was positively correlated with muscle mass (r = 0.367 and 0.311, respectively; p = 0.005 for both). Conclusion: A low intake of calories, protein, and leucine is associated with reduced muscle mass in hip-fractured elderly. Given the relevance of sarcopenia as a risk factor for adverse outcomes in this patient population, our findings highlight the importance of a comprehensive dietary assessment for the detection of nutritional deficits predisposing to or aggravating muscle atrophy.

Lifestyle habits, host gene repertoire, and alterations in the intestinal microbiota concur to the development of obesity. A great deal of research has recently been focused on investigating the role gut microbiota plays in the pathogenesis of metabolic dysfunctions and increased adiposity. Altered microbiota can affect host physiology through several pathways, including enhanced energy harvest, and perturbations in immunity, metabolic signaling, and inflammatory pathways. A broad range of "omics" technologies is now available to help decipher the interactions between the host and the gut microbiota at detailed genetic and functional levels. In particular, metabolomics - the comprehensive analysis of metabolite composition of biological fluids and tissues - could provide breakthrough insights into the links among the gut microbiota, host genetic repertoire, and diet during the development and progression of obesity. Here, we briefly review the most insightful findings on the involvement of gut microbiota in the pathogenesis of obesity. We also discuss how metabolomic approaches based on nuclear magnetic resonance spectroscopy could help understand the activity of gut microbiota in relation to obesity, and assess the effects of gut microbiota modulation in the treatment of this condition.

Advanced age per se is a major risk factor for cardiovascular disease (CVD). Apart from the chronic exposure to known cardiovascular risk factors, intrinsic aging of the cardiovascular system amplifies the vulnerability to various stressors, ultimately favoring the development of CVD in late life. The process of cardiac aging involves derangements in multiple cellular pathways. Among these, impairments in mitochondrial function arising from failure of mitochondrial quality control are considered to be a major contributing factor to heart senescence. Besides being less bioenergetically efficient, damaged mitochondria produce larger amounts of reactive oxygen species and are more prone to induce apoptosis. This results in oxidative damage to cardiomyocyte components and dismissal of postmitotic and virtually irreplaceable cardiac cells. The chapter summarizes the current knowledge about prominent mechanisms and consequences of mitochondrial decay and failure of mitochondrial quality control in the context of cardiac aging. The therapeutic potential of targeting specific mitochondrial pathways is also discussed.

Background Aging is characterized by derangements in multiple metabolic pathways that progressively constrict the homeostatic reserve (homeostenosis). The signature of metabolic alterations that accompany aging can be retrieved through the metabolomic profiling of biological fluids. Objective To characterize the age-related changes in urinary and fecal metabolic profiles of BALB/c mice through a 1 H nuclear magnetic resonance (NMR)-based metabolomic approach. Methods Young (n = 19) and old (n = 13) male BALB/c mice were fed ad libitum standard laboratory chow. Twenty four-hour feces and urine were collected using metabolic cages and analyzed by high-resolution 1 H NMR spectroscopy combined with multivariate statistical analyses. Results An age-related metabolic phenotype was detected both in urine and feces. The metabolic signature of aging consisted of changes in levels of metabolites associated with amino acid metabolism, tricarboxylic acid cycle, tryptophan–nicotinamide adenine dinucleotide pathway, and host–microbiota metabolic axis. Conclusions Our 1 H NMR-based metabolomic approach was able to characterize the effect of age on urinary and fecal metabotypes. The implementation of this analytical strategy may increase our understanding of the metabolic alterations involved in the aging process and assist in the design of anti-aging interventions.

Serum concentrations of the C-terminal fragment of agrin (CAF), a component of the neuromuscular junction (NMJ), are elevated in older community-dwellers with sarcopenia. Whether CAF may be used as a marker for muscle wasting in the presence of NMJ mechanical damage is presently unknown. The present study was undertaken to verify if serum CAF levels were associated with sarcopenia in older hip fractured patients.Analyses were conducted in older adults hospitalized for traumatic hip fracture. The presence of sarcopenia was established according to the European Working Group on Sarcopenia in Older People criteria, with bioelectrical impedance analysis used for muscle mass estimation. Serum levels of CAF were determined using a commercial ELISA kit.Among 42 hip fractured patients (age 83.7±8.6 years, 76.2% women), sarcopenia was diagnosed in 7 individuals (16.7%). Serum CAF levels were significantly higher in sarcopenic relative to non-sarcopenic patients (172.2±47.5 pM vs. 93.1±44.0 pM; p0.001). The association remained significant in both genders after adjustment for several potential confounders.Elevated serum CAF concentrations are associated with sarcopenia in older adults with hip fracture. The determination of serum CAF levels could therefore serve to identify a subset of hip fractured patients at especially high risk for adverse health outcomes.

The current healthcare systems are built around the traditional paradigm of patients suffering from a single acute illness. They are therefore largely unprepared to face the increasing demands for health services arising from the expansion of an older population with specific medical needs related to multiple chronic disorders. As a consequence, the medical conditions of a large and growing segment of the older European population are not efficiently managed by the available healthcare services (1). Among these conditions, the geriatric syndrome of frailty has emerged as a significant public health priority. I

Advanced age is associated with a disproportionate prevalence of cardiovascular disease (CVD). Intrinsic alterations in the heart and the vasculature occurring over the life course render the cardiovascular system more vulnerable to various stressors in late life, ultimately favoring the development of CVD. Several lines of evidence indicate mitochondrial dysfunction as a major contributor to cardiovascular senescence. Besides being less bioenergetically efficient, damaged mitochondria also produce increased amounts of reactive oxygen species, with detrimental structural and functional consequences for the cardiovascular system. The agerelated accumulation of dysfunctional mitochondrial likely results from the combination of impaired clearance of damaged organelles by autophagy and inadequate replenishment of the cellular mitochondrial pool by mitochondriogenesis. In this review, we summarize the current knowledge about relevant mechanisms and consequences of age-related mitochondrial decay and alterations in mitochondrial quality control in the cardiovascular system. The involvement of mitochondrial dysfunction in the pathogenesis of cardiovascular conditions especially prevalent in late life and the emerging connections with neurodegeneration are also illustrated. Special emphasis is placed on recent discoveries on the role played by alterations in mitochondrial dynamics (fusion and fission), mitophagy, and their interconnections in the context of age-related CVD and endothelial dysfunction. Finally, we discuss pharmacological interventions targeting mitochondrial dysfunction to delay cardiovascular aging and manage CVD. © 2013 the American Physiological Society.

Sarcopenia, the age-related loss of muscle mass and function, imposes a dramatic burden on individuals and society. The development of preventive and therapeutic strategies against sarcopenia is therefore perceived as an urgent need by health professionals and has instigated intensive research on the pathophysiology of this syndrome. The pathogenesis of sarcopenia is multifaceted and encompasses lifestyle habits, systemic factors (e.g., chronic inflammation and hormonal alterations), local environment perturbations (e.g., vascular dysfunction), and intramuscular specific processes. In this scenario, derangements in skeletal myocyte mitochondrial function are recognized as major factors contributing to the age-dependent muscle degeneration. In this review, we summarize prominent findings and controversial issues on the contribution of specific mitochondrial processes - including oxidative stress, quality control mechanisms and apoptotic signaling - on the development of sarcopenia. Extramuscular alterations accompanying the aging process with a potential impact on myocyte mitochondrial function are also discussed. We conclude with presenting methodological and safety considerations for the design of clinical trials targeting mitochondrial dysfunction to treat sarcopenia. Special emphasis is placed on the importance of monitoring the effects of an intervention on muscle mitochondrial function and identifying the optimal target population for the trial. This article is part of a Directed Issue entitled: Molecular basis of muscle wasting. © 2013 Elsevier Ltd. All rights reserved.

Recently, we showed that administration of the angiotensin-converting enzyme inhibitor enalapril to aged rats attenuated muscle strength decline and mitigated apoptosis in the gastrocnemius muscle. The aim of the present study was to investigate possible mechanisms underlying the muscle-protective effects of enalapril. We also sought to discern the effects of enalapril mediated by nitric oxide (NO) from those independent of this signaling molecule. Eighty-seven male Fischer 344 × Brown Norway rats were randomly assigned to receive enalapril (n = 23), the NO synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME; n = 22), enalapril + L-NAME (n = 19), or placebo (n = 23) from 24 to 27 months of age. Experiments were performed on the tibialis anterior muscle. Total NOS activity and the expression of neuronal, endothelial, and inducible NOS isoforms (nNOS, eNOS, and iNOS) were determined to investigate the effects of enalapril on NO signaling. Transcript levels of tumor necrosis factor-alpha (TNF-α) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) were assessed to explore actions of enalapril on inflammation and mitochondrial biogenesis, respectively. Protein expression of energy-sensing and insulin signaling mediators, including protein kinase B (Akt-1), phosphorylated Akt-1 (pAkt-1), mammalian target of rapamycin (mTOR), AMP-activated protein kinase subunit alpha (AMPKα), phosphorylated AMPKα (pAMPKα), and the glucose transporter GLUT-4, was also determined. Finally, the generation of hydrogen peroxide (H2O2) was quantified in subsarcolemmal (SSM) and intermyofibrillar (IFM) mitochondria. Enalapril increased total NOS activity, which was prevented by L-NAME co-administration. eNOS protein content was enhanced by enalapril, but not by enalapril + L-NAME. Gene expression of iNOS was down-regulated by enalapril either alone or in combination with L-NAME. In contrast, protein levels of nNOS were unaltered by treatments. The mRNA abundance of TNF-α was reduced by enalapril relative to placebo, with no differences among any other group. PCG-1α gene expression was unaffected by enalapril and lowered by enalapril + L-NAME. No differences in protein expression of Akt-1, pAkt-1, AMPKα, pAMPKα, or GLUT-4 were detected among groups. However, mTOR protein levels were increased by enalapril compared with placebo. Finally, all treatment groups displayed reduced SSM, but not IFM H2O2 production relative to placebo. Our data indicate that enalapril induces a number of metabolic adaptations in aged skeletal muscle. These effects result from the concerted modulation of NO and angiotensin II signaling, rather than from a dichotomous action of enalapril on the two pathways. Muscle protection by enalapril administered late in life appears to be primarily mediated by mitigation of oxidative stress and pro-inflammatory signaling.

Aging is accompanied by a progressive decline in skeletal muscle mass and function, known as sarcopenia, which leads to decreased overall physical function, increased risk for frailty, and ultimately loss of independent living and death. A combination of nutritional interventions and exercise (both resistance and aerobic) is currently considered the most effective strategy to prevent and treat sarcopenia. The aim of this chapter is to review the current knowledge on the role of nutrition in combating muscle aging and to introduce the most recent dietary strategies to preserve muscle mass and function in late life.

Objective Sarcopaenia and physical function impairment may have a greater effect on survival than other clinical characteristics, including multimorbidity. In this study, we evaluated the impact of sarcopaenia on all-cause mortality and the interaction among muscle loss, physical function impairment and multimorbidity on mortality risk over 10 years in older community-dwellers. Design Prospective cohort study. Setting Population-based study. Participants All persons aged 80+ years living in the community in the Sirente geographic area (L'Aquila, Italy) (n=364). Participants were categorised in the sarcopaenic or non-sarcopaenic group based on the European Working Group on Sarcopenia in Older People criteria. Primary and secondary outcome measures (1) All-cause mortality over 10 years according to the presence of sarcopaenia and (2) impact of physical function impairment, assessed using the Short Physical Performance Battery (SPPB), and multimorbidity on 10-year mortality risk in persons with sarcopaenia. Results Sarcopaenia was identified in 103 participants (29.1%). A total of 253 deaths were recorded over 10 years: 90 among sarcopaenic participants (87.4%) and 162 among non-sarcopaenic persons (65.1%; p

Older people frequently fail to ingest adequate amount of food to meet their essential energy and nutrient requirements. Anorexia of aging, defined by decrease in appetite and/or food intake in old age, is a major contributing factor to under-nutrition and adverse health outcomes in the geriatric population. This disorder is indeed highly prevalent and is recognized as an independent predictor of morbidity and mortality in different clinical settings. Even though anorexia is not an unavoidable consequence of aging, advancing age often promotes its development through various mechanisms. Age-related changes in life-style, disease conditions, as well as social and environmental factors have the potential to directly affect dietary behaviors and nutritional status. In spite of their importance, problems related to food intake and, more generally, nutritional status are seldom attended to in clinical practice. While this may be the result of an “ageist” approach, it should be acknowledged that simple interventions, such as oral nutritional supplementation or modified diets, could meaningfully improve the health status and quality of life of older persons.

Background Preclinical studies strongly suggest that accelerated apoptosis in skeletal myocytes may be involved in the pathogenesis of sarcopenia. However, evidence in humans is sparse. In the present study, we investigated whether apoptotic signaling in the skeletal muscle was associated with indices of muscle mass and function in older persons. Methodology/Principal Findings Community-dwelling older adults were categorized into high-functioning (HF) or low-functioning (LF) groups according to their short physical performance battery (SPPB) summary score. Participants underwent an isokinetic knee extensor strength test and 3-dimensional magnetic resonance imaging of the thigh. Vastus lateralis muscle samples were obtained by percutaneous needle biopsy and assayed for the expression of a set of apoptotic signaling proteins. Age, sex, number of comorbid conditions and medications as well as knee extensor strength were not different between groups. HF participants displayed greater thigh muscle volume compared with LF persons. Multivariate partial least squares (PLS) regressions showed significant correlations between caspase-dependent apoptotic signaling proteins and the muscular percentage of thigh volume (R2 = 0.78; Q2 = 0.61) as well as gait speed (R2 = 0.81; Q2 = 0.56). Significant variables in the PLS model of percent muscle volume were active caspase-8, cleaved caspase-3, cytosolic cytochrome c and mitochondrial Bak. The regression model of gait speed was mainly described by cleaved caspase-3 and mitochondrial Bax and Bak. PLS predictive apoptotic variables did not differ between functional groups. No correlation was determined between apoptotic signaling proteins and muscle strength or quality (strength per unit volume). Conclusions/Significance Data from this exploratory study show for the first time that apoptotic signaling is correlated with indices of muscle mass and function in a cohort of community-dwelling older persons. Future larger-scale studies are needed to corroborate these preliminary findings and determine if down-regulation of apoptotic signaling in skeletal myocytes will provide improvements in the muscle mass and functional status of older persons.