Developmental influences, muscle morphology, and sarcopenia in community-dwelling older men

The effect of low birth weight as an intrauterine exposure on the early onset of sarcopenia through possible molecular pathways

Sarcopenia, a musculoskeletal disease characterized by the progressive loss of skeletal muscle mass, strength, and physical performance, presents significant challenges to global public health due to its adverse effects on mobility, morbidity, mortality, and healthcare costs. This comprehensive review explores the intricate connections between sarcopenia and low birth weight (LBW), emphasizing the developmental origins of health and disease (DOHaD) hypothesis, inflammatory processes (inflammaging), mitochondrial dysfunction, circadian rhythm disruptions, epigenetic mechanisms, and genetic variations revealed through genome-wide studies (GWAS). A systematic search strategy was developed using PubMed to identify relevant English-language publications on sarcopenia, LBW, DOHaD, inflammaging, mitochondrial dysfunction, circadian disruption, epigenetic mechanisms, and GWAS. The publications consist of 46.2% reviews, 21.2% cohort studies, 4.8% systematic reviews, 1.9% cross-sectional studies, 13.4% animal studies, 4.8% genome-wide studies, 5.8% epigenome-wide studies, and 1.9% book chapters. The review identified key factors contributing to sarcopenia development, including the DOHaD hypothesis, LBW impact on muscle mass, inflammaging, mitochondrial dysfunction, the influence of clock genes, the role of epigenetic mechanisms, and genetic variations revealed through GWAS. The DOHaD theory suggests that LBW induces epigenetic alterations during foetal development, impacting long-term health outcomes, including the early onset of sarcopenia. LBW correlates with reduced muscle mass, grip strength, and lean body mass in adulthood, increasing the risk of sarcopenia. Chronic inflammation (inflammaging) and mitochondrial dysfunction contribute to sarcopenia, with LBW linked to increased oxidative stress and dysfunction. Disrupted circadian rhythms, regulated by genes such as BMAL1 and CLOCK, are associated with both LBW and sarcopenia, impacting lipid metabolism, muscle mass, and the ageing process. Early-life exposures, including LBW, induce epigenetic modifications like DNA methylation (DNAm) and histone changes, playing a pivotal role in sarcopenia development. Genome-wide studies have identified candidate genes and variants associated with lean body mass, muscle weakness, and sarcopenia, providing insights into genetic factors contributing to the disorder. LBW emerges as a potential early predictor of sarcopenia development, reflecting the impact of intrauterine exposures on long-term health outcomes. Understanding the complex interplay between LBW with inflammaging, mitochondrial dysfunction, circadian disruption, and epigenetic factors is essential for elucidating the pathogenesis of sarcopenia and developing targeted interventions. Future research on GWAS and the underlying mechanisms of LBW-associated sarcopenia is warranted to inform preventive strategies and improve public health outcomes.

The Toxic Stress of Racism and Its Relationship to Frailty

Significant morbidity and mortality from COVID-19-related illnesses have been observed among people of color within the United States. While theories involving healthcare inequity and political division have emerged to explain this observation, the role of chronic stress and inflammation is also being explored. Toxic stress is experienced disproportionately by race, ethnicity, and socioeconomic status and increases frailty and vulnerability to diseases such as COVID-19. C-reactive protein (CRP) is a biomarker associated with the inflammatory response that is typically elevated due to exposure to acute or chronic traumatic stress, as well as COVID-19. This study explored the relationship between CRP and Hispanic/non-Hispanic ethnicity among adults hospitalized with COVID-19 via a secondary analysis of retrospective electronic health record (EHR) data collected from a community healthcare system in Southern California. A total of 1,744 cases representing hospitalized adults with COVID-19 were reviewed. Data were extracted from the EHR to reflect demographics, medical diagnoses, medications, CRP, and comorbidity burden. Frequencies, percentages, and measures of central tendency were assessed to understand the distribution of data. Associations were conducted using Pearson's r and the chi-square test of independence. Differences between groups were examined via independent samples t-tests. The sample was 52% Hispanic, 56% male, and the mean age was 62 years (SD = 16.1). The mean age of Hispanic cases was younger than non-Hispanic cases (p < .001, η = 0.289). Serum CRP was significantly higher in the Hispanic cases, with a high degree of association (p < .001, η = 0.472). In addition, higher CRP levels were significantly associated with the need for mechanical ventilation (p < .001, φc = 0.216). No significant relationships were found between CRP and age, body mass index (BMI), or comorbidity burden. Findings challenge the assumption that the disproportionate morbidity and mortality suffered by the Hispanic population due to COVID-19 was due to age, BMI, or comorbidities such as metabolic syndrome or heart disease. CRP in the Hispanic population should be further investigated to understand its relationship to chronic stress, frailty, and risk for COVID-19 in this population.

Various Organ Damages in Rats with Fetal Growth Restriction and Their Slight Attenuation by Bifidobacterium breve Supplementation

Children with fetal growth restriction (FGR) and its resultant low birthweight (LBW) are at a higher risk of developing various health problems later in life, including renal diseases, metabolic syndrome, and sarcopenia. The mechanism through which LBW caused by intrauterine hypoperfusion leads to these health problems has not been properly investigated. Oral supplementation with probiotics is expected to reduce these risks in children. In the present study, rat pups born with FGR-LBW after mild intrauterine hypoperfusion were supplemented with either Bifidobacterium breve (B. breve) or a vehicle from postnatal day 1 (P1) to P21. Splanchnic organs and skeletal muscles were evaluated at six weeks of age. Compared with the sham group, the LBW-vehicle group presented significant changes as follows: overgrowth from infancy to childhood; lighter weight of the liver, kidneys, and gastrocnemius and plantaris muscles; reduced height of villi in the ileum; and increased depth of crypts in the jejunum. Some of these changes were milder in the LBW-B.breve group. In conclusion, this rat model could be useful for investigating the mechanisms of how FGR-LBW leads to future health problems and for developing interventions for these problems. Supplementation with B. breve in early life may modestly attenuate these problems.

Pathogenesis, Intervention, and Current Status of Drug Development for Sarcopenia: A Review

Sarcopenia refers to the loss of muscle strength and mass in older individuals and is a major determinant of fall risk and impaired ability to perform activities of daily living, often leading to disability, loss of independence, and death. Owing to its impact on morbidity, mortality, and healthcare expenditure, sarcopenia in the elderly has become a major focus of research and public policy debates worldwide. Despite its clinical importance, sarcopenia remains under-recognized and poorly managed in routine clinical practice, partly owing to the lack of available diagnostic testing and uniform diagnostic criteria. Since the World Health Organization and the United States assigned a disease code for sarcopenia in 2016, countries worldwide have assigned their own disease codes for sarcopenia. However, there are currently no approved pharmacological agents for the treatment of sarcopenia; therefore, interventions for sarcopenia primarily focus on physical therapy for muscle strengthening and gait training as well as adequate protein intake. In this review, we aimed to examine the latest information on the epidemiology, molecular mechanisms, interventions, and possible treatments with new drugs for sarcopenia.

Determinants of muscle density and clinical outcomes: Findings from the Hertfordshire Cohort Study

PURPOSE

The age-related loss of skeletal muscle mass and strength is associated with adverse health outcomes. However, to date, peripheral quantitative computed tomography (pQCT)-derived muscle density has been little studied. We used a well characterised cohort of older adults to identify lifestyle and anthropometric determinants of pQCT-derived muscle density measured 11 years later, and to report relationships between pQCT-derived muscle density with history of falls and prevalent fractures.

METHODS

A lifestyle questionnaire was administered to 197 men and 178 women, aged 59-70 at baseline. After a median of 11.5 (IQR 10.9, 12.3) years, pQCT (Stratec XCT2000) of the radius and tibia was performed to measure forearm muscle density (FMD) and calf muscle density (CMD). Presence of falls and fractures since the age of 45 were determined through participant recall; vertebral fractures were also ascertained through vertebral fracture assessment using iDXA. Total hip BMD (TH aBMD) was assessed using DXA. Baseline characteristics in relation to muscle density at follow-up were examined using linear regression; associations between muscle density and prior falls and fractures were investigated using logistic regression. All analyses were adjusted for sex and age.

RESULTS

Mean (SD) age at muscle density measurement was 76.3 (2.6) years. Mean (SD) FMD was 79.9 (3.1) and 77.2 (3.2) among males and females, respectively; CMD was 80.7 (2.6) and 78.5 (2.6) among males and females, respectively. Significant sex-differences in muscle density were observed at each site (p < 0.001). Female sex, lower weight, and lower body mass index were associated (p < 0.05) with both lower FMD and CMD. Additional correlates of lower CMD included older age and shorter stature. Lifestyle measures were not associated with muscle density in this cohort. Lower FMD was related to increased risk of previous fracture (odds ratio (95 % CI) per SD lower FMD: 1.42 (1.07, 1.89), p = 0.015) but not after adjustment for TH aBMD (p > 0.08). No significant relationships were seen between muscle density and falls.

CONCLUSION

Female sex, older age, and lower BMI were associated with subsequent lower muscle density in older community-dwelling adults. Lower FMD was related to increased risk of previous fracture. Changes in muscle density over time might precede adverse outcomes such as falls and fractures and may be a long-term predictor of frailty. It could be also suggested that muscle density could be a more clinically meaningful surrogate of functional decline and disability than muscle size or mass, but more studies are needed to support this notion.

Impact of Body Mass Index on Muscle Strength, Thicknesses, and Fiber Composition in Young Women

High body mass index (BMI) may influence muscle strength, muscle thickness (Mtk), and fiber composition. We evaluated these parameters in 31 and 27 women grouped in non-oral contraceptive (non-OC) groups and OC groups, respectively, and further divided them into groups based on BMI: BMI_low, BMI_norm, and BMI_high. Maximum isometric force (F_max), Mtk, and the relative percentage of muscle fiber composition (%) were examined in both groups. F_max and Mtk values were significantly greater in the BMI_high than the BMI_low within the OC group. However, there was no significant difference in the non-OC group. BMI_low and BMI_norm groups showed a difference in the distribution of muscle fiber types 1 and 2 with almost the same proportions in both non-OC and OC groups. However, the BMI_high group showed a difference in the distribution of muscle fiber types 1 and 2, with type 1 about 18.76% higher in the non-OC group. Contrastively, type 2 was about 34.35% higher in the OC group. In this study, we found that there was a significant difference in F_max and Mtk according to the BMI level in the OC group, but no significant difference was found in the non-OC group. Moreover, the distribution of type 2 muscle fibers tended to be higher in the OC group of BMI_high, although the sample size was small. Therefore, although no significant difference of F_max and Mtk was found according to BMI level in the non-OC group in this study, the increase in BMI level appeared to be more associative of muscle strength in the OC group. Based on the present results, future studies are needed that consider the BMI level as well as the presence or absence of OC in future research about women's muscle strength.

A Review of Sarcopenia Pathophysiology, Diagnosis, Treatment and Future Direction

Sarcopenia is a progressive and generalized loss of skeletal muscle mass and function. The prevalence of sarcopenia was reported to be up to 29% in older persons in the community healthcare setting. Sarcopenia diagnosis is confirmed by the presence of low muscle mass plus low muscle strength or low physical performance. Sarcopenia management options include non-pharmacological and pharmacological approaches. Non-pharmacological approaches include resistance exercise and adequate nutrition. Of the two, resistance exercise is the standard non-pharmacological treatment approach for sarcopenia with significant positive evidence. Some dietary approaches such as adequate intake of protein, vitamin D, antioxidant nutrients, and long-chain polyunsaturated fatty acid have been shown to have positive effects against sarcopenia. Currently, no specific drugs have been approved by the Food and Drug Administration for the treatment of sarcopenia. However, several agents, including growth hormone, anabolic or androgenic steroids, selective androgenic receptor modulators, protein anabolic agents, appetite stimulants, myostatin inhibitors, activating II receptor drugs, β-receptor blockers, angiotensin-converting enzyme inhibitors, and troponin activators, are recommended and have been shown to have variable efficacy. Future research should focus on sarcopenia biological pathway and improved diagnostic approaches such as biomarkers for early detection, development of consistently pre-eminent treatment methods for severe sarcopenia patients, and establishing sensitive measures for predicting sarcopenia treatment response.

Fitness Changes in Adolescent Girls Following In-School Combined Aerobic and Resistance Exercise: Interaction With Birthweight

PURPOSE

To assess the efficacy of a supervised in-school combined resistance and aerobic training program in adolescent girls and investigate whether responses differ according to birthweight.

METHODS

Participants (girls aged 13-17 y) were randomized either to an intervention replacing physical education (PE) classes with 2 × 60-minute training sessions per week (n = 58) or to a control group that continued to attend 2 × 60 minutes per week of curriculum PE (n = 41). We measured muscular fitness (handgrip, standing long jump, and sit-ups), cardiorespiratory fitness (20-m shuttle run), skinfolds, and lean body mass preintervention and postintervention and determined effect size (Hedge's g) differences between changes in these measures. We also compared changes within lower (<3000 g) and normal birthweight intervention and PE control subgroups.

RESULTS

The intervention group showed greater improvements in all the fitness measures and lean body mass (g = 0.22-0.48) and lower skinfold increases (g = 0.41) than PE controls. Within the intervention group, improvements in all fitness measures were larger in lower birthweight (g = 0.53-0.94) than in normal birthweight girls (g = 0.02-0.39).

CONCLUSION

Replacing curriculum PE with supervised training improved muscular and cardiorespiratory fitness and body composition outcomes in adolescent females. Our findings suggest an enhanced adaptive response to training in participants with lower birthweight which warrants further investigation.

Maternal low protein diet and fetal programming of lean type 2 diabetes

Maternal nutrition is found to be the key factor that determines fetal health in utero and metabolic health during adulthood. Metabolic diseases have been primarily attributed to impaired maternal nutrition during pregnancy, and impaired nutrition has been an immense issue across the globe. In recent years, type 2 diabetes (T2D) has reached epidemic proportion and is a severe public health problem in many countries. Although plenty of research has already been conducted to tackle T2D which is associated with obesity, little is known regarding the etiology and pathophysiology of lean T2D, a variant of T2D. Recent studies have focused on the effects of epigenetic variation on the contribution of in utero origins of lean T2D, although other mechanisms might also contribute to the pathology. Observational studies in humans and experiments in animals strongly suggest an association between maternal low protein diet and lean T2D phenotype. In addition, clear sex-specific disease prevalence was observed in different studies. Consequently, more research is essential for the understanding of the etiology and pathophysiology of lean T2D, which might help to develop better disease prevention and treatment strategies. This review examines the role of protein insufficiency in the maternal diet as the central driver of the developmental programming of lean T2D.

Prenatal Low-Protein Diet Affects Mitochondrial Structure and Function in the Skeletal Muscle of Adult Female Offspring

Gestational low-protein (LP) diet leads to glucose intolerance and insulin resistance in adult offspring. We had earlier demonstrated that LP programming affects glucose disposal in females. Mitochondrial health is crucial for normal glucose metabolism in skeletal muscle. In this study, we sought to analyze mitochondrial structure, function, and associated genes in skeletal muscles to explore the molecular mechanism of insulin resistance LP-programmed female offspring. On day four of pregnancy, rats were assigned to a control diet containing 20% protein or an isocaloric 6% protein-containing diet. Standard laboratory diet was given to the dams after delivery until the end of weaning and to pups after weaning. Gestational LP diet led to changes in mitochondrial ultrastructure in the gastrocnemius muscles, including a nine-fold increase in the presence of giant mitochondria along with unevenly formed cristae. Further, functional analysis showed that LP programming caused impaired mitochondrial functions. Although the mitochondrial copy number did not show significant changes, key genes involved in mitochondrial structure and function such as Fis1, Opa1, Mfn2, Nrf1, Nrf2, Pgc1b, Cox4b, Esrra, and Vdac were dysregulated. Our study shows that prenatal LP programming induced disruption in mitochondrial ultrastructure and function in the skeletal muscle of female offspring.

Birth Weight was Favorably Associated With Physical Fitness in Childhood After Adjustment for Several Perinatal Factors

BACKGROUND

The purpose was to examine the potential associations of birth weight and infant growth with physical fitness (PF) components in childhood.

METHOD

A random sample of 5125 dyads of children aged 8-9 years and their mothers were evaluated. Telephone interviews were carried out with the use of a standardized questionnaire for the collection of maternal lifestyle factors. Mothers were asked to provide information contained in their medical booklets and pregnancy ultrasound records. Data from 5 PF tests were used to assess cardiorespiratory fitness, speed, and body strength. Linear regression analysis was applied to assess the associations between birth weight and infant growth with PF test performances and logistic regression analysis to evaluate the associations of normal weight versus low birth weight and normal versus accelerated infant growth with PF tests performance categories (low vs high/average).

RESULTS

Birth weight was favorably associated with cardiorespiratory fitness (b = 0.12 stage increase per SD increase in birth weight, P = .047), lower body strength (b = 1.07, P = .037), upper body strength (b = 0.10, P = .038), and speed (b = -0.04, P = .001), and infant growth was associated with upper body strength (b = 0.21 cm increase per SD increase in infant weight gain, P < .001) after adjusting for children's body mass index and several perinatal factors. Low birth weight children had 35% increased odds for low performances in PF tests compared with their normal birth weight counterparts.

CONCLUSION

Low birth weight negatively affects childhood PF, and hence, it could play an unfavorable role in the future health of the offspring.

Myostatin and Follistatin-New Kids on the Block in the Diagnosis of Sarcopenia in IBD and Possible Therapeutic Implications

Sarcopenia, which is a decrease in muscle strength and quality of muscle tissue, is a common disorder among patients suffering from inflammatory bowel disease. This particular group of patients often presents with malnutrition and shows low physical activity, which increases the risk of sarcopenia. Another important factor in the development of sarcopenia is an imbalanced ratio of myostatin and follistatin, which may stem from inflammation as well as genetic factors. Currently, research in this area continues, and is aimed at identifying an effective medication for the treatment of this condition. Additionally, we still have no sarcopenia markers that can be used for diagnosis. In this paper, we address the role of myostatin and follistatin as potential markers in the diagnosis of sarcopenia in patients with Crohn’s disease and ulcerative colitis, particularly in view of the genetic and biological aspects. We also present data on new perspectives in the pharmacotherapy of sarcopenia (i.e., myostatin inhibitors and gene therapy). Nevertheless, knowledge is still scarce about the roles of follistatin and myostatin in sarcopenia development among patients suffering from inflammatory bowel disease, which warrants further study.

Small-RNA Sequencing Reveals Altered Skeletal Muscle microRNAs and snoRNAs Signatures in Weanling Male Offspring from Mouse Dams Fed a Low Protein Diet during Lactation

Maternal diet during gestation and lactation affects the development of skeletal muscles in offspring and determines muscle health in later life. In this paper, we describe the association between maternal low protein diet-induced changes in offspring skeletal muscle and the differential expression (DE) of small non-coding RNAs (sncRNAs). We used a mouse model of maternal protein restriction, where dams were fed either a normal (N, 20%) or a low protein (L, 8%) diet during gestation and newborns were cross-fostered to N or L lactating dams, resulting in the generation of NN, NL and LN offspring groups. Total body and tibialis anterior (TA) weights were decreased in weanling NL male offspring but were not different in the LN group, as compared to NN. However, histological evaluation of TA muscle revealed reduced muscle fibre size in both groups at weaning. Small RNA-sequencing demonstrated DE of multiple miRs, snoRNAs and snRNAs. Bioinformatic analyses of miRs-15a, -34a, -122 and -199a, in combination with known myomiRs, confirmed their implication in key muscle-specific biological processes. This is the first comprehensive report for the DE of sncRNAs in nutrition-associated programming of skeletal muscle development, highlighting the need for further research to unravel the detailed molecular mechanisms.

Low birth weight and its relation to physical fitness parameters in children: Its negative effect on muscle strength and cardiorespiratory endurance

BACKGROUND

There is increasing evidence that low birth weight has a negative effect on physical fitness, muscle strength, and cardiorespiratory endurance, although the findings are inconsistent.

OBJECTIVES

This study aimed to evaluate whether birth weight acts as a prenatal determinant of physical fitness parameters and to determine the role of environmental or biological variables on this effect.

METHODS

One hundred and sixty-seven children aged 6-14 years were included in this study. The anthropometric data, physical activity index, standing long jump, flexibility, handgrip strength, and cardiorespiratory fitness were evaluated.

RESULTS

A positive correlation was found between birth weight and cardiorespiratory fitness (r = .349; p < .001), right handgrip strength (r = .337; p < .001), and left handgrip strength (r = .320; p < .001), suggesting that children with low birth weight had the worst performance in both cardiorespiratory endurance and grip strength tests. These findings remained significant after adjustment for prematurity, sex, age, physical activity index, and body mass index (BMI). Stepwise multiple regression analyses revealed a significant interaction of high birth weight, older age, and low BMI in predicting better cardiorespiratory endurance (R² = .308). When handgrip strength was tested as the dependent variable, we found that high birth weight, male sex, and older age emerged as important determinants for both sides.

CONCLUSION

Children aged 6-14 years born with a birth weight < 2.5 kg have low handgrip strength and cardiorespiratory fitness, which seems to be mediated partially by influences of both prenatal environment (e.g., birth weight) and biological variables (e.g., age, sex, BMI).

A Vicious Cycle of Osteosarcopeniain Inflammatory Bowel Diseases-Aetiology, Clinical Implications and Therapeutic Perspectives

Sarcopenia is a disorder characterized by a loss of muscle mass which leads to the reduction of muscle strength and a decrease in the quality and quantity of muscle. It was previously thought that sarcopenia was specific to ageing. However, sarcopenia may affect patients suffering from chronic diseases throughout their entire lives. A decreased mass of muscle and bone is common among patients with inflammatory bowel disease (IBD). Since sarcopenia and osteoporosis are closely linked, they should be diagnosed as mutual consequences of IBD. Additionally, multidirectional treatment of sarcopenia and osteoporosis including nutrition, physical activity, and pharmacotherapy should include both disorders, referred to as osteosarcopenia.

Sarcopenia: A Contemporary Health Problem among Older Adult Populations

Sarcopenia, a geriatric disease characterized by a progressive loss of skeletal muscle mass and loss of muscle function, constitutes a rising, often undiagnosed health problem. Its prevalence in the elderly population is largely considered variable, as it ranges from 5% to 50% depending on gender, age, pathological conditions as well as diagnostic criteria. There is no one unified approach of treatment or assessment, which makes sarcopenia even harder to assess. There is a pressing need to provide better diagnosis, diagnostics, prevention, and individualized health care. Physical activity and nutrition are the main studied ways to prevent sarcopenia, and they also offer better outcomes. This review aims to report the prevalence of sarcopenia in older adults, its etiology, prevention, and treatment techniques.

Getting to grips with sarcopenia: recent advances and practical management for the gastroenterologist

Sarcopenia is a progressive and generalised disorder of skeletal muscle strength, function and mass, that is most commonly associated with the normal ageing process. It is increasingly recognised that sarcopenia can also develop as a consequence of malabsorptive and inflammatory conditions, such as those seen by gastroenterologists and hepatologists. It affects 1%-30% of the general population, but is seen in approximately 40% of patients with gastrointestinal conditions including inflammatory bowel disease and cirrhosis. Within this group of patients, it is associated with increased complications and mortality. The pathogenesis of sarcopenia is multifactorial with several risk factors implicated in its development including undernutrition, physical inactivity and coexistent multimorbidity. The SARC-F questionnaire has been developed to screen for patients at risk of sarcopenia, however, this focuses on the functional consequences and will therefore not identify those patients who are early in the progression of sarcopenia. There are several different non-invasive techniques available to assess muscle quantity and quality including; grip strength, dual energy X-ray absorptiometry, CT which can be used together to diagnose sarcopenia. Assessment and correction of malnutrition, particularly protein intake, in those at risk of sarcopenia is important in preventing the development and progression of sarcopenia. There are no specific drugs that are available for the treatment of sarcopenia, however, resistance exercise programmes combined with nutritional interventions show promise. It is important that this common condition is screened for and recognised, with any contributing factors addressed to reduce the risk of its progression.

Impact of sarcopenia in trauma and surgical patient population: A literature review

Sarcopenia refers to the progressive and generalised loss of skeletal muscle mass and strength with a risk of adverse outcomes such as physical disability, poor quality of life and mortality. The present review explored the impact, diagnosis, prevention and management of sarcopenia in surgical and trauma patients. Recent evidence suggests that there are many factors contributing to its development other than age. Pathophysiology of sarcopenia is complex which makes its diagnosis difficult and there is no universal approach. It is a predictor of poor outcomes including post-operative complications, length of hospital stay and mortality in trauma and surgery patients. Sedentary lifestyle, age-dependent hormone and cytokine imbalance, decreased protein synthesis and regeneration, and motor unit remodelling are some of the main risk factors for sarcopenia. Dual energy X-ray absorptiometry, bio-electrical impedance analysis and computed tomography are frequently utilized for its diagnosis. Management of sarcopenia involves appropriate management of comorbidities, interventions to facilitate physical activities, nutrition interventions and pharmacotherapy.

Birth weight and grip strength in young Swedish males: a longitudinal matched sibling analysis and across all body mass index ranges

Low birth weight is associated with a lower grip strength later in life. However, associations between birth weight among infants born at-term and factors driving associations between birth weight and grip strength are largely unknown. A cohort of 144,369 young men born at-term, including 10,791 individuals who had at least one male sibling/s, were followed until conscription where they performed a grip strength test. We used linear and non-linear regression analyses in the full cohort, and fixed-effects regression analyses in the sibling cohort, to address confounding by factors that are shared between siblings. After adjustment, each unit increase in birth weight z-score was associated with increases of 17.7 (95% CI, 17.2–18.2) and 13.4 (10.1–16.6) newton grip strength, which converts to approximately 1.8 and 1.4 kilogram-force in the full and within-families cohorts, respectively. The associations did not vary with young adulthood BMI. Birth weight, within the at-term range, is robustly positively associated with grip strength in young adulthood among men across all BMI categories and associations appears to be mainly driven by factors that are not shared between siblings. These findings underline the importance of recognizing the influence of low birth weight, also within the at-term-range, on young adulthood muscle strength.

Quadriceps miR-542-3p and -5p are elevated in COPD and reduce function by inhibiting ribosomal and protein synthesis

Reduced physical performance reduces quality of life in patients with chronic obstructive pulmonary disease (COPD). Impaired physical performance is, in part, a consequence of reduced muscle mass and function, which is accompanied by mitochondrial dysfunction. We recently showed that miR-542-3p and miR-542-5p were elevated in a small cohort of COPD patients and more markedly in critical care patients. In mice, these microRNAs (miRNAs) promoted mitochondrial dysfunction suggesting that they would affect physical performance in patients with COPD, but we did not explore the association of these miRNAs with disease severity or physical performance further. We therefore quantified miR-542-3p/5p and mitochondrial rRNA expression in RNA extracted from quadriceps muscle of patients with COPD and determined their association with physical performance. As miR-542-3p inhibits ribosomal protein synthesis its ability to inhibit protein synthesis was also determined in vitro. Both miR-542-3p expression and -5p expression were elevated in patients with COPD (5-fold P < 0.001) and the degree of elevation associated with impaired lung function (transfer capacity of the lung for CO in % and forced expiratory volume in 1 s in %) and physical performance (6-min walk distance in %). In COPD patients, the ratio of 12S rRNA to 16S rRNA was suppressed suggesting mitochondrial ribosomal stress and mitochondrial dysfunction and miR-542-3p/5p expression was inversely associated with mitochondrial gene expression and positively associated with p53 activity. miR-542-3p suppressed RPS23 expression and maximal protein synthesis in vitro. Our data show that miR-542-3p and -5p expression is elevated in COPD patients and may suppress physical performance at least in part by inhibiting mitochondrial and cytoplasmic ribosome synthesis and suppressing protein synthesis. NEW & NOTEWORTHY miR-542-3p and -5p are elevated in the quadriceps muscle of patients with chronic obstructive pulmonary disease (COPD) in proportion to the severity of their lung disease. These microRNAs inhibit mitochondrial and cytoplasmic protein synthesis suggesting that they contribute to impaired exercise performance in COPD.

Grip strength among Indigenous and non-Indigenous Australian adults: a longitudinal study of the effects of birth size and current size

OBJECTIVES

Indigenous Australians are born smaller than non-Indigenous Australians and are at an increased risk of early onset of frailty. This study aimed to identify the relationship between birth size, current size and grip strength, as an early marker of frailty, in Indigenous and non-Indigenous young adults.

DESIGN

Cross sectional data from two longitudinal studies: Aboriginal birth cohort (Indigenous) and top end cohort (non-Indigenous).

SETTING

Participants reside in over 40 urban and remote communities across the Northern Territory, Australia.

PARTICIPANTS

Young adults with median age 25 years (IQR 24-26); 427 participants (55% women), 267 (63%) were remote Indigenous, 55 (13%) urban Indigenous and 105 (25%) urban non-Indigenous.

OUTCOME MEASURES

Reliable birth data were available. Anthropometric data (height, weight, lean mass) and grip strength were directly collected using standardised methods. Current residence was classified as urban or remote.

RESULTS

The rate of low birthweight (LBW) in the non-Indigenous cohort (9%) was significantly lower than the Indigenous cohort (16%) (-7%, 95% CI -14 to 0, p=0.03). Indigenous participants had lower grip strength than non-Indigenous (women, -2.08, 95% CI -3.61 to -0.55, p=0.008 and men, -6.2, 95% CI -9.84 to -2.46, p=0.001). Birth weight (BW) was associated with grip strength after adjusting for demographic factors for both women (β=1.29, 95% CI 0.41 to 2.16, p=0.004) and men (β=3.95, 95% CI 2.38 to 5.51, p<0.001). When current size (lean mass and body mass index [BMI]) was introduced to the model BW was no longer a significant factor. Lean mass was a positive indicator for grip strength, and BMI a negative indicator.

CONCLUSIONS

As expected women had significantly lower grip strength than men. Current size, in particular lean mass, was the strongest predictor of adult grip strength in this cohort. BW may have an indirect effect on later grip strength via moderation of lean mass development, especially through adolescence and young adulthood.

The Hertfordshire Cohort Study: an overview

The Hertfordshire Cohort Study is a nationally unique study of men and women born in the English county of Hertfordshire in the early part of the 20 ^th century. Records that detail their health in infancy and childhood have been preserved, their sociodemographic, lifestyle, medical and biological attributes have been characterised in later life, and routinely collected data on their hospital use and mortality have been acquired. This paper provides an overview of the study since its inception in the 1980s, including its methods, findings, and plans for its future.

Age at natural menopause and physical function in older women from Albania, Brazil, Colombia and Canada: A life-course perspective

OBJECTIVE

Grip strength and gait speed are objective measures of physical function, which in turn is an indicator of biological aging. We evaluate the association between age at natural menopause (ANM) and physical functioning in a sample of postmenopausal women drawn from the International Mobility in Aging Study (IMIAS).

STUDY DESIGN

Retrospective cohort study of 775 women aged 65-74, from Albania, Brazil, Colombia and Canada, who had experienced natural menopause.

MAIN OUTCOME MEASURES

Gait speed and grip strength were obtained following standardized protocols. The association between self-reported ANM (<40, 40-44, 45-49, 50-54 and ≥55) and gait speed (m/s) and grip strength (kg) was assessed by linear regression analyses adjusting for several life-course economic and reproductive exposures, height, BMI and smoking.

RESULTS

Overall, women with ANM ≥ 55 had higher gait speed than those with ANM 50-54 (β = 0.05; 95%CI: 0.01, 0.10). Women with ANM < 40 had significantly lower grip strength compared with all other groups (β= -2.58; 95%CI: -4.43, -0.74). In region-specific analyses, ANM was associated with grip strength in Albania and Latin America and with gait speed in Albania only. No associations were observed in Canada.

CONCLUSIONS

ANM is associated with markers of physical functioning. Differences across study sites suggest that women in socially disadvantaged areas may reach menopause with different physiological reserves than those from more advantaged settings, leading to greater losses in muscle strength in postmenopausal years. More work comparing distinct populations is needed to better understand the underlying mechanisms.

Sarcopenia: A Rheumatic Disease?

Sarcopenia refers to the age-related loss of muscle mass, muscle strength, and physical function. With an increase in the number and proportion of elderly in the population, sarcopenia is a growing global health concern due to its impact on morbidity, mortality, and health care expenditure. Despite its clinical importance, sarcopenia remains underrecognized and poorly managed in routine clinical practice. This is, in part, due to a lack of available diagnostic testing and uniform diagnostic criteria. This article provides the general practitioner or rheumatologist an overview of the pathophysiology, diagnosis, and management of this complex and critical entity.

miR-424-5p reduces ribosomal RNA and protein synthesis in muscle wasting

BACKGROUND

A loss of muscle mass occurs as a consequence of a range of chronic and acute diseases as well as in older age. This wasting results from an imbalance of protein synthesis and degradation with a reduction in synthesis and resistance to anabolic stimulation often reported features. Ribosomes are required for protein synthesis, so changes in the control of ribosome synthesis are potential contributors to muscle wasting. MicroRNAs (miRNAs) are known regulators of muscle phenotype and have been shown to modulate components of the protein synthetic pathway. One miRNA that is predicted to target a number of components of protein synthetic pathway is miR-424-5p, which is elevated in the quadriceps of patients with chronic obstructive pulmonary disease (COPD).

METHODS

Targets of miR-424-5p were identified by Argonaute2 pull down, and the effects of the miRNA on RNA and protein expression were determined by quantitative polymerase chain reaction and western blotting in muscle cells in vitro. Protein synthesis was determined by puromycin incorporation in vitro. The miRNA was over-expressed in the tibialis anterior muscle of mice by electroporation and the effects quantified. Finally, quadriceps expression of the miRNA was determined by quantitative polymerase chain reaction in patients with COPD and intensive care unit (ICU)-acquired weakness and in patients undergoing aortic surgery as well as in individuals from the Hertfordshire Sarcopenia Study.

RESULTS

Pull-down assays showed that miR-424-5p bound to messenger RNAs encoding proteins associated with muscle protein synthesis. The most highly enriched messenger RNAs encoded proteins required for the Pol I RNA pre-initiation complex required for ribosomal RNA (rRNA) transcription, (PolR1A and upstream binding transcription factor). In vitro, miR-424-5p reduced the expression of these RNAs, reduced rRNA levels, and inhibited protein synthesis. In mice, over-expression of miR-322 (rodent miR-424 orthologue) caused fibre atrophy and reduced upstream binding transcription factor expression and rRNA levels. In humans, elevated miR-424-5p associated with markers of disease severity in COPD (FEV₁ %), in patients undergoing aortic surgery (LVEF%), and in patients with ICU-acquired weakness (days in ICU). In patients undergoing aortic surgery, preoperative miR-424-5p expression in skeletal muscle was associated with muscle loss over the following 7 days.

CONCLUSIONS

These data suggest that miR-424-5p regulates rRNA synthesis by inhibiting Pol I pre-initiation complex formation. Increased miR-424-5p expression in patients with conditions associated with muscle wasting is likely to contribute to the inhibition of protein synthesis and loss of muscle mass.

Human Skeletal Muscle Possesses an Epigenetic Memory of Hypertrophy

It is unknown if adult human skeletal muscle has an epigenetic memory of earlier encounters with growth. We report, for the first time in humans, genome-wide DNA methylation (850,000 CpGs) and gene expression analysis after muscle hypertrophy (loading), return of muscle mass to baseline (unloading), followed by later hypertrophy (reloading). We discovered increased frequency of hypomethylation across the genome after reloading (18,816 CpGs) versus earlier loading (9,153 CpG sites). We also identified AXIN1, GRIK2, CAMK4, TRAF1 as hypomethylated genes with enhanced expression after loading that maintained their hypomethylated status even during unloading where muscle mass returned to control levels, indicating a memory of these genes methylation signatures following earlier hypertrophy. Further, UBR5, RPL35a, HEG1, PLA2G16, SETD3 displayed hypomethylation and enhanced gene expression following loading, and demonstrated the largest increases in hypomethylation, gene expression and muscle mass after later reloading, indicating an epigenetic memory in these genes. Finally, genes; GRIK2, TRAF1, BICC1, STAG1 were epigenetically sensitive to acute exercise demonstrating hypomethylation after a single bout of resistance exercise that was maintained 22 weeks later with the largest increase in gene expression and muscle mass after reloading. Overall, we identify an important epigenetic role for a number of largely unstudied genes in muscle hypertrophy/memory.

Pathogenesis and Management of Sarcopenia

Sarcopenia represents a loss of muscle strength and mass in older individuals. Sarcopenia in the elderly has now become a major focus of research and public policy debate due to its impact on morbidity, mortality, and health care expenditure. Despite its clinical importance, sarcopenia remains under-recognized and poorly managed in routine clinical practice. This is, in part, due to a lack of available diagnostic testing and uniform diagnostic criteria. The management of sarcopenia is primarily focused on physical therapy for muscle strengthening and gait training. There are no pharmacologic agents for the treatment of sarcopenia.

Impact of placental insufficiency on fetal skeletal muscle growth

Intrauterine growth restriction (IUGR) caused by placental insufficiency is one of the most common and complex problems in perinatology, with no known cure. In pregnancies affected by placental insufficiency, a poorly functioning placenta restricts nutrient supply to the fetus and prevents normal fetal growth. Among other significant deficits in organ development, the IUGR fetus characteristically has less lean body and skeletal muscle mass than their appropriately-grown counterparts. Reduced skeletal muscle growth is not fully compensated after birth, as individuals who were born small for gestational age (SGA) from IUGR have persistent reductions in muscle mass and strength into adulthood. The consequences of restricted muscle growth and accelerated postnatal "catch-up" growth in the form of adiposity may contribute to the increased later life risk for visceral adiposity, peripheral insulin resistance, diabetes, and cardiovascular disease in individuals who were formerly IUGR. This review will discuss how an insufficient placenta results in impaired fetal skeletal muscle growth and how lifelong reductions in muscle mass might contribute to increased metabolic disease risk in this vulnerable population.

Body composition and the monitoring of non-communicable chronic disease risk

There is a need for simple proxies of health status, in order to improve monitoring of chronic disease risk within and between populations, and to assess the efficacy of public health interventions as well as clinical management. This review discusses how, building on recent research findings, body composition outcomes may contribute to this effort. Traditionally, body mass index has been widely used as the primary index of nutritional status in children and adults, but it has several limitations. We propose that combining information on two generic traits, indexing both the ‘metabolic load’ that increases chronic non-communicable disease risk, and the homeostatic ‘metabolic capacity’ that protects against these diseases, offers a new opportunity to improve assessment of disease risk. Importantly, this approach may improve the ability to take into account ethnic variability in chronic disease risk. This approach could be applied using simple measurements readily carried out in the home or community, making it ideal for M-health and E-health monitoring strategies.

Poor maternal nutrition and accelerated postnatal growth induces an accelerated aging phenotype and oxidative stress in skeletal muscle of male rats

‘Developmental programming’, which occurs as a consequence of suboptimal in utero and early environments, can be associated with metabolic dysfunction in later life, including an increased incidence of cardiovascular disease and type 2 diabetes, and predisposition of older men to sarcopenia. However, the molecular mechanisms underpinning these associations are poorly understood. Many conditions associated with developmental programming are also known to be associated with the aging process. We therefore utilized our well-established rat model of low birth weight and accelerated postnatal catch-up growth (termed ‘recuperated’) in this study to establish the effects of suboptimal maternal nutrition on age-associated factors in skeletal muscle. We demonstrated accelerated telomere shortening (a robust marker of cellular aging) as evidenced by a reduced frequency of long telomeres (48.5-8.6 kb) and an increased frequency of short telomeres (4.2-1.3 kb) in vastus lateralis muscle from aged recuperated offspring compared to controls. This was associated with increased protein expression of the DNA-damage-repair marker 8-oxoguanine-glycosylase (OGG1) in recuperated offspring. Recuperated animals also demonstrated an oxidative stress phenotype, with decreased citrate synthase activity, increased electron-transport-complex activities of complex I, complex II-III and complex IV (all markers of functional mitochondria), and increased xanthine oxidase (XO), p67^phox and nuclear-factor kappa-light-chain-enhancer of activated B-cells (NF-κB). Recuperated offspring also demonstrated increased antioxidant defense capacity, with increased protein expression of manganese superoxide dismutase (MnSOD), copper-zinc superoxide dismutase (CuZnSOD), catalase and heme oxygenase-1 (HO1), all of which are known targets of NF-κB and can be upregulated as a consequence of oxidative stress. Recuperated offspring also had a pro-inflammatory phenotype, as evidenced by increased tumor necrosis factor-α (TNFα) and interleukin-1β (IL1β) protein levels. Taken together, we demonstrate, for the first time to our knowledge, an accelerated aging phenotype in skeletal muscle in the context of developmental programming. These findings may pave the way for suitable interventions in at-risk populations.

Summary: Muscle of ‘developmentally programmed’ rat offspring demonstrated accelerated aging and oxidative stress, which could explain why some individuals are at greater risk of developing age-associated muscular dysfunction than others.

Does skeletal muscle have an 'epi'-memory? The role of epigenetics in nutritional programming, metabolic disease, aging and exercise

Skeletal muscle mass, quality and adaptability are fundamental in promoting muscle performance, maintaining metabolic function and supporting longevity and healthspan. Skeletal muscle is programmable and can ‘remember’ early‐life metabolic stimuli affecting its function in adult life. In this review, the authors pose the question as to whether skeletal muscle has an ‘epi’‐memory? Following an initial encounter with an environmental stimulus, we discuss the underlying molecular and epigenetic mechanisms enabling skeletal muscle to adapt, should it re‐encounter the stimulus in later life. We also define skeletal muscle memory and outline the scientific literature contributing to this field. Furthermore, we review the evidence for early‐life nutrient stress and low birth weight in animals and human cohort studies, respectively, and discuss the underlying molecular mechanisms culminating in skeletal muscle dysfunction, metabolic disease and loss of skeletal muscle mass across the lifespan. We also summarize and discuss studies that isolate muscle stem cells from different environmental niches in vivo (physically active, diabetic, cachectic, aged) and how they reportedly remember this environment once isolated in vitro. Finally, we will outline the molecular and epigenetic mechanisms underlying skeletal muscle memory and review the epigenetic regulation of exercise‐induced skeletal muscle adaptation, highlighting exercise interventions as suitable models to investigate skeletal muscle memory in humans. We believe that understanding the ‘epi’‐memory of skeletal muscle will enable the next generation of targeted therapies to promote muscle growth and reduce muscle loss to enable healthy aging.

Increased expression of H19/miR-675 is associated with a low fat-free mass index in patients with COPD

BACKGROUND

Loss of muscle mass and strength is a significant comorbidity in patients with chronic obstructive pulmonary disease (COPD) that limits their quality of life and has prognostic implications but does not affect everyone equally. To identify mechanisms that may contribute to the susceptibility to a low muscle mass, we investigated microRNA (miRNA) expression, methylation status, and regeneration in quadriceps muscle from COPD patients and the effect of miRNAs on myoblast proliferation in vitro. The relationships of miRNA expression with muscle mass and strength was also determined in a group of healthy older men.

METHODS

We identified miRNAs associated with a low fat-free mass (FFM) phenotype in a small group of patients with COPD using a PCR screen of 750 miRNAs. The expression of two differentially expressed miRNAs (miR-675 and miR-519a) was determined in an expanded group of COPD patients and their associations with FFM and strength identified. The association of these miRNAs with FFM and strength was also explored in a group of healthy community-dwelling older men. As the expression of the miRNAs associated with FFM could be regulated by methylation, the relative methylation of the H19 ICR was determined. Furthermore, the proportion of myofibres with centralized nuclei, as a marker of muscle regeneration, in the muscle of COPD patients was identified by immunofluorescence.

RESULTS

Imprinted miRNAs (miR-675 and from a cluster, C19MC which includes miR-519a) were differentially expressed in the quadriceps of patients with a low fat-free mass index (FFMI) compared to those with a normal FFMI. In larger cohorts, miR-675 and its host gene (H19) were higher in patients with a low FFMI and strength. The association of miR-519a expression with FFMI was present in male patients with severe COPD. Similar associations of miR expression with lean mass and strength were not observed in healthy community dwelling older men participating in the Hertfordshire Sarcopenia Study. Relative methylation of the H19 ICR was reduced in COPD patients with muscle weakness but was not associated with FFM. In vitro, miR-675 inhibited myoblast proliferation and patients with a low FFMI had fewer centralized nuclei suggesting miR-675 represses regeneration.

CONCLUSIONS

The data suggest that increased expression of miR-675/H19 and altered methylation of the H19 imprinting control region are associated with a low FFMI in patients with COPD but not in healthy community dwelling older men suggesting that epigenetic control of this loci may contribute to a susceptibility to a low FFMI.

Prenatal Undernutrition and Physical Function and Frailty at the Age of 68 Years: The Dutch Famine Birth Cohort Study

BACKGROUND

There is evidence suggesting that the aging process has its origins in utero. We have previously shown that prenatal exposure to the Dutch famine is associated with chronic noncommunicable diseases and poorer cognitive function in men and women and increased mortality in women. We investigated whether prenatal undernutrition during early gestation is associated with decreased physical function in later life.

METHODS

Between November 2012 and September 2013, we have studied a random subsample of 150 members of the Dutch famine birth cohort at the age of 68 years, of which 49 were exposed to prenatal undernutrition. In this observational study, we measured indicators of physical function including grip strength and the short physical performance battery. We composed categories of frailty, according to the Fried frailty scale. We also assessed self-reported activity and self-perceived health.

RESULTS

Men, but not women, exposed to prenatal undernutrition had significantly lower grip strength (B = -4.2kg; 95% confidence interval: -8.2 to -0.3) and a lower physical performance score (B = -0.8 points; 95% confidence interval: -1.5 to 0.0) than unexposed men, independent of relevant confounders. There were no differences in frailty, self-reported activity, or self-perceived health between exposed and unexposed groups.

CONCLUSIONS

Our study results suggest that prenatal undernutrition is associated with decreased physical function in later life in men, but not in women. Our findings provide further evidence for the hypothesis that prenatal undernutrition may lead to an accelerated aging process in humans. We currently do not have sufficient power to detect effects on frailty.

Human Vastus Lateralis Skeletal Muscle Biopsy Using the Weil-Blakesley Conchotome

Percutaneous muscle biopsy using the Weil-Blakesley conchotome is well established in both clinical and research practice. It is a safe, effective and well tolerated technique. The Weil-Blakesley conchotome has a sharp biting tip with a 4 - 6 mm wide hollow. It is inserted through a 5 - 10 mm skin incision and can be maneuvered for controlled tissue penetration. The tip is opened and closed within the tissue and then rotated through 90 -180° to cut the muscle. The amount of muscle obtained following repeated sampling can vary from 20 mg to 290 mg which can be processed for both histology and molecular studies. The wound needs to be kept dry and vigorous physical activity kept to a minimum for approximately 72 hr although normal levels of activity can restart immediately following the procedure. This procedure is safe and effective when close attention is paid to the selection of subjects, full asepsis and post procedure care.  Both right and left vastus lateralis are suitable for biopsy dependent on participant preference.

Skeletal muscle cells possess a 'memory' of acute early life TNF-α exposure: role of epigenetic adaptation

Sufficient quantity and quality of skeletal muscle is required to maintain lifespan and healthspan into older age. The concept of skeletal muscle programming/memory has been suggested to contribute to accelerated muscle decline in the elderly in association with early life stress such as fetal malnutrition. Further, muscle cells in vitro appear to remember the in vivo environments from which they are derived (e.g. cancer, obesity, type II diabetes, physical inactivity and nutrient restriction). Tumour-necrosis factor alpha (TNF-α) is a pleiotropic cytokine that is chronically elevated in sarcopenia and cancer cachexia. Higher TNF-α levels are strongly correlated with muscle loss, reduced strength and therefore morbidity and earlier mortality. We have extensively shown that TNF-α impairs regenerative capacity in mouse and human muscle derived stem cells [Meadows et al. (J Cell Physiol 183(3):330-337, 2000); Foulstone et al. (J Cell Physiol 189(2):207-215, 2001); Foulstone et al. (Exp Cell Res 294(1):223-235, 2004); Stewart et al. (J Cell Physiol 198(2):237-247, 2004); Al-Shanti et al. (Growth factors (Chur, Switzerland) 26(2):61-73, 2008); Saini et al. (Growth factors (Chur, Switzerland) 26(5):239-253, 2008); Sharples et al. (J Cell Physiol 225(1):240-250, 2010)]. We have also recently established an epigenetically mediated mechanism (SIRT1-histone deacetylase) regulating survival of myoblasts in the presence of TNF-α [Saini et al. (Exp Physiol 97(3):400-418, 2012)]. We therefore wished to extend this work in relation to muscle memory of catabolic stimuli and the potential underlying epigenetic modulation of muscle loss. To enable this aim; C2C12 myoblasts were cultured in the absence or presence of early TNF-α (early proliferative lifespan) followed by 30 population doublings in the absence of TNF-α, prior to the induction of differentiation in low serum media (LSM) in the absence or presence of late TNF-α (late proliferative lifespan). The cells that received an early plus late lifespan dose of TNF-α exhibited reduced morphological (myotube number) and biochemical (creatine kinase activity) differentiation vs. control cells that underwent the same number of proliferative divisions but only a later life encounter with TNF-α. This suggested that muscle cells had a morphological memory of the acute early lifespan TNF-α encounter. Importantly, methylation of myoD CpG islands were increased in the early TNF-α cells, 30 population doublings later, suggesting that even after an acute encounter with TNF-α, the cells have the capability of retaining elevated methylation for at least 30 cellular divisions. Despite these fascinating findings, there were no further increases in myoD methylation or changes in its gene expression when these cells were exposed to a later TNF-α dose suggesting that this was not directly responsible for the decline in differentiation observed. In conclusion, data suggest that elevated myoD methylation is retained throughout muscle cells proliferative lifespan as result of early life TNF-α treatment and has implications for the epigenetic control of muscle loss.

Birth weight, intrauterine growth restriction and nutritional status in childhood in relation to grip strength in adults: from the 1982 Pelotas (Brazil) birth cohort

Objective

The aim of this study was to evaluate the association among birth weight, intrauterine growth, and nutritional status in childhood with grip strength in young adults from the 1982 Pelotas (Brazil) birth cohort.

Methods

In 1982, the hospital live births of Pelotas were followed. In 2012, grip strength was evaluated using a hand dynamometer and the best of the six measurements was used. Birth weight was analyzed as z-score for gestational age according to Williams (1982) curve. Weight-for-age, weight-for-length/height, and length/height-for-age at 2 and 4 y were analyzed in z-scores according to 2006 World Health Organization Child Growth Standards. Lean mass at 30 y was included as possible mediator using the g-computation formula.

Results

In 2012, 3701 (68.1%) individuals were interviewed and 3470 were included in the present analyses. An increase of 1 z-score in birth weight was associated with an increase of 1.5 kg in grip strength in males (95% confidence interval, 1.1–1.9). Positive effect of birth weight on grip strength was found in females. Grip strength was greater in individuals who were born with appropriate size for gestational age and positively associated with weight- and length/height-for-age z-score at 2 and 4 y of age. A positive association between birth weight and grip strength was only partially mediated by adult lean mass (50% and 33% of total effect in males and females), whereas direct effect of weight at 2 y was found only in males.

Conclusions

It is suggested that good nutrition in prenatal and early postnatal life has a positive influence on adult muscle strength. The results from birth weight were suggestive of fetal programming on grip strength measurement.

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Newborns from southern Brazil were followed for 30 y.

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Birth weight and nutritional status in childhood were prospectively measured.

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Grip strength was positively related to birth weight and early nutritional status.

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Coefficients of the association between birth weight and grip strength were higher in males.

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Birth weight was associated with adult grip strength independent of current lean mass.

Social and economic conditions in childhood and the progression of functional health problems from midlife into old age

BACKGROUND

Childhood living conditions have been found to predict health and mortality in midlife and in old age. This study examines the associations between social and economic childhood conditions and the onset and progression of functional health problems from midlife into old age, and the extent to which potential associations are mediated by educational attainment and smoking.

METHODS

Data from the Level of Living Survey and the Swedish Panel Study of Living Conditions of the Oldest Old were merged to create a longitudinal data set with five repeated measures from 1968 to 2004 (n=1765, aged 30-50 years and free from functional health problems at baseline). Multilevel regression models were used to analyse retrospective reports of social and economic conditions in childhood (eg, conflicts or economic problems in the family) in relation to the progression of functional health problems over the 36-year period.

RESULTS

Results showed that social and economic disadvantages in childhood were associated with an earlier onset and a faster progression of functional health problems from midlife into old age. Subsequent models showed that differences in educational attainment, but not smoking, explained much of the association between childhood disadvantages and trajectories of functional health problems.

CONCLUSIONS

According to these results, adverse social and economic conditions in childhood affect the development of functional health problems from midlife into old age indirectly through less favourable life careers, including lower education. Creating equal opportunities for educational attainment may help reduce the long-term effects of disadvantaged childhood conditions and postpone functional health problems.

Lower maternal body condition during pregnancy affects skeletal muscle structure and glut-4 protein levels but not glucose tolerance in mature adult sheep

Suboptimal maternal nutrition and body composition are implicated in metabolic disease risk in adult offspring. We hypothesized that modest disruption of glucose homeostasis previously observed in young adult sheep offspring from ewes of a lower body condition score (BCS) would deteriorate with age, due to changes in skeletal muscle structure and insulin signaling mechanisms. Ewes were fed to achieve a lower (LBCS, n = 10) or higher (HBCS, n = 14) BCS before and during pregnancy. Baseline plasma glucose, glucose tolerance and basal glucose uptake into isolated muscle strips were similar in male offspring at 210 ± 4 weeks. Vastus total myofiber density (HBCS, 343 ± 15; LBCS, 294 ± 14 fibers/mm(2), P < .05) and fast myofiber density (HBCS, 226 ± 10; LBCS 194 ± 10 fibers/mm(2), P < .05), capillary to myofiber ratio (HBCS, 1.5 ± 0.1; LBCS 1.2 ± 0.1 capillary:myofiber, P < .05) were lower in LBCS offspring. Vastus protein levels of Akt1 were lower (83% ± 7% of HBCS, P < .05), and total glucose transporter 4 was increased (157% ± 6% of HBCS, P < .001) in LBCS offspring, Despite the reduction in total myofiber density in LBCS offspring, glucose tolerance was normal in mature adult life. However, such adaptations may lead to complications in metabolic control in an overabundant postnatal nutrient environment.

Birth weight and growth from infancy to late adolescence in relation to fat and lean mass in early old age: findings from the MRC National Survey of Health and Development

Objective:

High birth weight and greater weight gain in infancy have been associated with increased risk of obesity as assessed using body mass index, but few studies have examined associations with direct measures of fat and lean mass. This study examined associations of birth weight and weight and height gain in infancy, childhood and adolescence with fat and lean mass in early old age.

Subjects:

A total of 746 men and 812 women in England, Scotland and Wales from the MRC National Survey of Health and Development whose heights and weights had been prospectively ascertained across childhood and adolescence and who had dual energy X-ray absorptiometry measures at age 60–64 years.

Methods:

Associations of birth weight and standardised weight and height (0–2 (weight only), 2–4, 4–7, 7–11, 11–15, 15–20 years) gain velocities with outcome measures were examined.

Results:

Higher birth weight was associated with higher lean mass and lower android/gynoid ratio at age 60–64 years. For example, the mean difference in lean mass per 1 standard deviation increase in birth weight was 1.54 kg in males (95% confidence interval=1.04, 2.03) and 0.78 kg in females (0.41, 1.14). Greater weight gain in infancy was associated with higher lean mass, whereas greater gains in weight in later childhood and adolescence were associated with higher fat and lean mass, and fat/lean and android/gynoid ratios. Across growth intervals greater height gain was associated with higher lean but not fat mass, and with lower fat/lean and android/gynoid ratios.

Conclusion:

Findings suggest that growth in early life may have lasting effects on fat and lean mass. Greater weight gain before birth and in infancy may be beneficial by leading to higher lean mass, whereas greater weight gain in later childhood and adolescence may be detrimental by leading to higher fat/lean and android/gynoid ratios.

New horizons in the pathogenesis, diagnosis and management of sarcopenia

Sarcopenia is the age-related loss of skeletal muscle mass and function. It is now recognised as a major clinical problem for older people and research in the area is expanding exponentially. One of the most important recent developments has been convergence in the operational definition of sarcopenia combining measures of muscle mass and strength or physical performance. This has been accompanied by considerable progress in understanding of pathogenesis from animal models of sarcopenia. Well-described risk factors include age, gender and levels of physical activity and this knowledge is now being translated into effective management strategies including resistance exercise with recent interest in the additional role of nutritional intervention. Sarcopenia is currently a major focus for drug discovery and development although there remains debate about the best primary outcome measure for trials, and various promising avenues to date have proved unsatisfactory. The concept of 'new tricks for old drugs' is, however, promising, for example, there is some evidence that the angiotensin-converting enzyme inhibitors may improve physical performance. Future directions will include a deeper understanding of the molecular and cellular mechanisms of sarcopenia and the application of a lifecourse approach to understanding aetiology as well as to informing the optimal timing of interventions.

Birth weight and muscle strength: a systematic review and meta-analysis

OBJECTIVE

Lower muscle strength is associated with a range of adverse health outcomes in later life. The variation in muscle strength between individuals is only partly accounted for by factors in adult life such as body size and physical activity. The aim of this review was to assess the strength of the association between intrauterine development (indicated by birth weight) and subsequent muscle strength.

DESIGN

Systematic review and meta-analysis of studies that assessed the association between birth weight and subsequent muscle strength.

RESULTS

Nineteen studies met inclusion criteria with 17 studies showing that higher birth weight was associated with greater muscle strength. Grip strength was used as a single measure of muscle strength in 15 studies. Meta-analysis (13 studies, 20 481 participants, mean ages 9.3 to 67.5) showed a 0.86 kg (95% CI 0.58, 1.15) increase in muscle strength per additional kilogram of birth weight, after adjustment for age, gender and height at the time of strength measurement.

CONCLUSION

This review has found consistent evidence of a positive association between birth weight and muscle strength which is maintained across the lifecourse. Future work will be needed to elucidate the biological mechanisms underlying this association, but it suggests the potential benefit of an early intervention to help people maintain muscle strength in later life.