Sarcopenic indices in community-dwelling older adults

Human primary myoblasts derived from paraspinal muscle reflect donor age as an experimental model of sarcopenia

BACKGROUND

Low back pain is a general phenomenon of aging, and surgery is an unavoidable choice to relieve severe back pain. The discarded surgical site during surgery is of high value for muscle and muscle-related research. This study investigated the age-dependent properties of patients' paraspinal muscles at the cellular level.

METHODS

To define an association of paraspinal muscle degeneration with sarcopenia, we analyzed lumbar paraspinal muscle and myoblasts isolated from donors of various ages (25-77 years). Preoperative evaluations were performed by bioimpedance analysis using the InBody 720, magnetic resonance (MR) imaging of the lumbar spine, and lumbar extension strength using a lumbar extension dynamometer. In addition, the growth and differentiation capacity of myoblasts obtained from the donor was determined using proliferation assay and western blotting.

RESULTS

The cross-sectional area of the lumbar paraspinal muscle decreased with age and was also correlated with the appendicular skeletal muscle index (ASM/height2). Human primary myoblasts isolated from paraspinal muscle preserved their proliferative capacity in vitro, which tended to decrease with donor age. The age-dependent decline in myoblast proliferation was correlated with levels of cell cycle inhibitory proteins (p16INK4a, p21CIP1, and p27KIP1) associated with cellular senescence. Primary myoblasts isolated from younger donors differentiated into multinucleate myotubes earlier and at a higher rate than those from older donors in vitro. Age-dependent decline in myogenic potential of the isolated primary myoblasts was likely correlated with the inactivation of myogenic transcription factors such as MyoD, myogenin, and MEF2c.

CONCLUSIONS

Myoblasts isolated from human paraspinal muscle preserve myogenic potential that correlates with donor age, providing an in vitro model of sarcopenia.

Prevalence of associations among sarcopenia, obesity, and metabolic syndrome in Brazilian older adults

BACKGROUND

Although aging is a process associated with the development of obesity, metabolic syndrome (MetS), and sarcopenia, the prevalence of these conditions in older adults from São Paulo, Brazil, is unclear.

METHODS

Therefore, the current study aimed to investigate the prevalence of obesity, sarcopenia, and MetS, both separately and together, in a community-based sample of older adults from São Paulo, Brazil. Data from the medical records of 418 older adults of both genders, aged 60  years or older (mean age 69.3 ± 6.5  years), who were not physically active, were used to conduct this retrospective cross-sectional study. Anthropometric variables were used to determine both body mass index (BMI) and Conicity index (C index). Sarcopenia and MetS were defined according to the criteria of the European Working Group on Sarcopenia in Older People and by the Brazilian Society of Endocrinology and Metabolism, respectively.

RESULTS

Based on BMI, the group of older men (n = 91) showed a predominance of adequate weight (n = 49) and the group of older women (n = 327) showed a predominance of obesity (n = 181). In association with obesity, while only the group of older women presented with sarcopenia (n = 5), 52 older women and 9 older men presented with MetS, and two older women presented with sarcopenia + MetS [prevalence ratio = 0.0385, 95% CI (0.007;0.1924)]. Based on the C index, 58 older women and 11 older men presented with MetS, while the occurrence of sarcopenia or MetS + sarcopenia was found in 32 and 5 older women, respectively [prevalence ratio = 0.0910, 95% CI (0.037;0.2241)].

DISCUSSION

Our results suggest that obesity, as measured by BMI or the C Index, was more closely associated with the occurrence of MetS than sarcopenia, regardless of gender, and also that sarcopenic obesity was only found in the group of older women. Additionally, the prevalence ratio of obesity, sarcopenia, and MetS evidenced using the C index was 2.3 times higher than the values found using the BMI classification.

Relative fat mass at baseline and its early change may be a predictor of incident nonalcoholic fatty liver disease

The relationship between changes in body components and the risk of nonalcoholic fatty liver disease (NAFLD) is not fully understood. We investigated the effects of body components and subsequent changes on incident NAFLD at follow-up ultrasound scanning in a longitudinal cohort. We included 9967 participants without NAFLD at baseline who underwent serial health examinations. Sex-specific, weight-adjusted skeletal muscle index (SMI_{_Wt}) was used. Mean follow-up duration was 48.5 ± 33.5 months. NAFLD developed in 2395 participants (24.0%). Body composition was measured using bioelectrical impedance analysis. The following baseline body components were significantly associated with incident NAFLD: the lowest and middle SMI_{_Wt} tertiles in the normal-weight group (adjusted hazard ratio [aHR] = 2.20 and 1.54, respectively), and fat percentage in the normal-weight (aHR = 1.12), overweight (aHR = 1.05), and obese groups (aHR = 1.03) (all P < 0.05). Among 5,033 participants who underwent ≥ 3 health examinations, SMI_{_Wt} increase between the first and second examinations was an independent protective factor against incident NAFLD in non-obese groups (P < 0.05). Increased fat percentage was an independent risk factor for incident NAFLD in all weight categories (P < 0.05). High fat mass at baseline may be a better predictor of incident NAFLD than muscle mass. Reciprocal changes in fat and muscle mass during the first year of follow-up predicted incident NAFLD in non-obese groups.

Normative Values of Knee Extensor Isokinetic Strength for Older Women and Implications for Physical Function

BACKGROUND AND PURPOSE

Lower-limb strength is required for everyday activities and thus its evaluation has been especially emphasized in older adults. Isokinetic testing is a criterion standard method to assess muscle strength; however, lack of reference values limits its usefulness in geriatric evaluation and rehabilitation. The aim of this study was to develop reference values of knee extensor isokinetic strength for older women. As a secondary aim, functional tests were performed for clinical significance validation.

METHODS

A total of 453 older women aged 60 to 84 years participated in this study. Knee extensor isokinetic strength was measured using the Biodex System dynamometer at 60° per second. The Timed Up and Go test and the 5 times Sit-to-Stand test were used for functional performance evaluation. Participants were categorized into age groups of 5 years range. The 20th, 40th, 60th, and 80th percentiles were used for stratification purposes.

RESULTS AND DISCUSSION

As expected, mean strength values significantly decreased with advancing age groups. Isokinetic percentile groups are presented according to age. Individuals in the lower percentile strata showed significantly reduced performance in both the Timed Up and Go and 5 times Sit-to-Stand tests (P < .05).

CONCLUSION

This study provides normative values of isokinetic knee extensor strength in older women. The association between lower isokinetic knee extensor strength strata and reduced functional capacity supports the potential application of these reference values in clinical and research settings. Future studies should ascertain these findings in different female populations.

Explanators of Sarcopenia in Individuals With Diabesity: A Cross-Sectional Analysis

BACKGROUND AND PURPOSE

Excess lower extremity intermuscular adipose tissue (IMAT), reduced strength, and functional limitations are common in obese individuals with and without diabetes (the former termed diabesity). Individuals with diabesity are particularly susceptible to accelerated sarcopenia, which may be underdiagnosed. The purpose of this study was to determine critical values for leg IMAT volume, plantar flexor (PF) muscle strength, and physical performance that help identify individuals with diabesity who have sarcopenia.

METHODS

Forty-three age- and sex-matched obese adults were studied: 12 with type 2 diabetes, 21 with diabetes and peripheral neuropathy, and 10 nondiabetic controls. Dual-energy x-ray absorptiometry-derived skeletal muscle index determined classification of sarcopenia. Leg fat (% IMAT), ankle (PF) peak torque, and power while ascending 10 steps, were used as explanators of sarcopenia. Receiver operating curves identified critical values for each explanator individually. Logistic regression models using all 3 explanators, and only PF torque and stair power, were also created. Receiver operating curve analyses identified the predicted probability that maximized each model's sensitivity and specificity. A leave-one-out cross validation was used to simulate the models' performance in an independent sample.

RESULTS AND DISCUSSION

Thirty-two participants were sarcopenic, and 11 were not. Critical values for individual explanators were 21% IMAT, 68 Nm PF torque, and 441 watts of stair power. Predicted probabilities of .76 and .67 were chosen as the optimal cutoff probabilities for the model combining all 3 explanators, and the model combining PF torque and stair power, respectively. The cross-validation analysis produced an accuracy of 82.4%, using the cutoff probability of .5, and an accuracy of 76.5% using the cutoff of 0.76. The area under the curve for the cross validation receiver operating curve analysis was 0.82. Critical values of leg % IMAT, PF torque, and stair power can classify individuals with diabesity as sarcopenic. The results of the cross validation give us confidence that the sample used in this study was representative of the target population, and suggests models created from this sample may perform well in externally derived data sets.

CONCLUSION

Clinicians may be able to use these critical values to select interventions that specifically target sarcopenia. Measures of % IMAT, PF torque, and stair power may offer a customized alternative to traditional sarcopenic classification systems, which may not be optimally suited to the common impairments among individuals with diabesity.

Weakness and Low Lean Mass in Women With Hip Fracture: Prevalence According to the FNIH Criteria and Association With the Short-Term Functional Recovery

BACKGROUND AND PURPOSE

People with hip fracture commonly have low muscle mass, reduced muscle strength, limited mobility, and limited ability to function in activities of daily living. Our aim was to assess the role of grip strength and appendicular lean mass (aLM) to predict the short-term functional recovery in women with hip fracture. For both strength and aLM, we focused on the cutoff points recently released by the Foundation for the National Institutes of Health (FNIH).

METHODS

In this short-term prospective observational study, we investigated 138 white women consecutively admitted to a rehabilitation hospital because of their first hip fracture. We measured aLM by dual-energy x-ray absorptiometry, grip strength with a hand dynamometer, and body mass index (BMI) at a median of 18 days after hip fracture occurrence. Functional autonomy was assessed by the Barthel index at the end of the rehabilitation course.

RESULTS

Fifty-five of the 138 women (40%; 95% confidence interval [CI], 32%-48%) had a handgrip strength less than 16 kg, whereas 33 (24%; 95% CI, 17%-31%) had a handgrip strength/BMI less than 0.56. In both cases, the weak women had Barthel index scores significantly lower than the nonweak women (P ≤ .001). One hundred eighteen of the 138 women (86%; 95% CI, 80%-91%) had an aLM less than 15.02 kg, whereas 65 (48%; 95% CI, 39%-56%) had an aLM/BMI less than 0.512. In both cases the Barthel index scores were nonsignificantly different between the women whose aLM indexes were either below or above the cutoff points.

CONCLUSIONS

Categorization according to the FNIH cutoff points for weakness significantly predicted the functional outcome in women with hip fracture, whereas categorization for aLM did not. Adjustments for BMI significantly changed the prevalence of either weakness or low aLM, but did not materially change their predictive roles.

Reduced Muscle Strength in Barth Syndrome May Be Improved by Resistance Exercise Training: A Pilot Study

BACKGROUND

Cardioskeletal myopathy is thought to contribute to exercise intolerance, and reduced quality of life (QOL) in Barth syndrome (BTHS). The objectives of this study were to examine: (1) skeletal muscle strength/performance in adolescents and young adults with BTHS and (2) the safety, feasibility, and initial efficacy of 12 weeks of progressive resistance exercise training (RET) on muscle strength, mass, and performance, bone mineral density, exercise tolerance, cardiac function, and QOL in individuals with BTHS.

METHODS

Individuals with BTHS (n = 9, 23 ± 6 years), and age-, sex-, and activity level-matched unaffected Controls (n = 7, 26 ± 5 years) underwent baseline testing to assess muscle performance, exercise capacity, cardiac structure and function, body composition, and health-related QOL. Subsequently, n = 3 participants with BTHS performed 12 weeks of supervised RET (60 min per session, 3 sessions/week). All testing was repeated post-RET.

RESULTS

BTHS had lower strength and lean muscle mass compared to Controls (all p < 0.05). BTHS also had diminished lower extremity, upper extremity, thoracic spine, lumbar spine, and pelvic bone mineral density (all p < 0.05) and reduced exercise capacity (p < 0.001) compared to Controls. RET was well-tolerated and attended, was not associated with any adverse events, and significantly increased muscle strength (p < 0.05).

CONCLUSIONS

Individuals with BTHS demonstrate reduced muscle strength and mass, bone mineral density, and exercise capacity. RET appears safe and well-tolerated in BTHS and promotes increased muscle strength. Larger studies are needed to confirm these improvements and to fully determine the effects of RET in individuals with BTHS.

Pitfalls in the measurement of muscle mass: a need for a reference standard

BACKGROUND

All proposed definitions of sarcopenia include the measurement of muscle mass, but the techniques and threshold values used vary. Indeed, the literature does not establish consensus on the best technique for measuring lean body mass. Thus, the objective measurement of sarcopenia is hampered by limitations intrinsic to assessment tools. The aim of this study was to review the methods to assess muscle mass and to reach consensus on the development of a reference standard.

METHODS

Literature reviews were performed by members of the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis working group on frailty and sarcopenia. Face-to-face meetings were organized for the whole group to make amendments and discuss further recommendations.

RESULTS

A wide range of techniques can be used to assess muscle mass. Cost, availability, and ease of use can determine whether the techniques are better suited to clinical practice or are more useful for research. No one technique subserves all requirements but dual energy X-ray absorptiometry could be considered as a reference standard (but not a gold standard) for measuring muscle lean body mass.

CONCLUSIONS

Based on the feasibility, accuracy, safety, and low cost, dual energy X-ray absorptiometry can be considered as the reference standard for measuring muscle mass.

Positive Effects of a Short-Term Intense Elastic Resistance Training Program on Body Composition and Physical Functioning in Overweight Older Women

The aim of this study was to investigate the effects of a resistance training program (RTP) in older overweight women (OOW) using two different types of elastic devices.

METHODS

This study was a randomized controlled trial with pre- and postintervention measures. Participants included OOW, aged 60-85 years, with no medical history of disease that would preclude them from engaging in physical exercise. Participants were randomly divided into the following groups: elastic tubes with handles group (ETG; n = 22), traditional elastic bands group ( n = 21), and control group (CG; n = 20). Exercise groups (EGs) performed the following supervised RTP: 8 weeks, twice weekly, six overall body exercises, and 3-4 sets of 10 repetitions at a rate of perceived exertion (RPE) of 7-9 on the OMNI-Resistance Exercise Scale of perceived exertion. The controls did not change their usual lifestyle. Outcome measures included body composition (BC; total and regional percentage of fat mass [FM] and fat-free mass [FFM]) and physical performance (PP; dynamic and isometric strength, flexibility, agility/dynamic balance, and endurance).

RESULTS

Both EGs exhibited significantly reduced FM in the upper limbs (ULs) and trunk and increased FFM in the UL, while the ETG exhibited a significantly increased trunk FFM. Both EGs improved in PP, and there were no intergroup differences. Trunk FM and FFM and meters walked differed significantly between the ETG and CG. The CG did not exhibit any significant changes.

CONCLUSION

Training with elastic devices at a moderate-high RPE produces short-term improvements in BC and PP in OOW.

Self-reported protein intake and properties of bone in community-dwelling older individuals

This study revealed that a quick and simple estimation of protein intake was related to measures of bone density and area in 70-year-old individuals. Furthermore, these associations were mediated by muscle mass when investigating peripheral measurement sites such as arms and legs.

PURPOSE

Recent evidence suggests that dietary protein is beneficial for bone health in older individuals, but less is known about the influence of muscle mass on this relationship. This cross-sectional study aimed to investigate associations among protein intake, bone health, and muscle mass in 2332 men and women aged 70 years.

METHODS

Volumetric bone mineral density of the radius and tibia was measured using peripheral quantitative computed tomography. Using dual-energy X-ray absorptiometry, we measured areal bone mineral density (aBMD) at the L1-L4 vertebrae, radius, and femoral neck, together with appendicular lean mass. Participants reported their average meal size and proportion of meat/fish intake. Associations were investigated using multiple linear regression models, adjusted for multiple covariates.

RESULTS

Self-reported protein intake was associated with aBMD of the femoral neck (β = 0.082) and L1-L4 vertebrae (β = 0.063) in men (both p < 0.05) after adjusting for multiple covariates, including appendicular muscle mass. No significant association was detected among women. In addition, protein intake was associated with tibial cortical area (β = 0.08), periosteal circumference (β = 0.072), radial aBMD (β = 0.064), and trabecular area (β = 0.078) in men (all p < 0.05), although these associations were attenuated after adjustment for appendicular muscle mass (all p > 0.05).

CONCLUSION

Self-reported protein intake was associated with bone properties in 70-year-old men. The strength of these associations in peripheral bone sites may be partially mediated by muscle mass from protein intake.

Effects of leucine-enriched essential amino acid and whey protein bolus dosing upon skeletal muscle protein synthesis at rest and after exercise in older women

BACKGROUND & AIMS

Impaired anabolic responses to nutrition and exercise contribute to loss of skeletal muscle mass with ageing (sarcopenia). Here, we tested responses of muscle protein synthesis (MPS), in the under represented group of older women, to leucine-enriched essential amino acids (EAA) in comparison to a large bolus of whey protein (WP).

METHODS

Twenty-four older women (65 ± 1 y) received (N = 8/group) 1.5 g leucine-enriched EAA supplements (LEAA_1.5), 6 g LEAA (LEAA_6) in comparison to 40 g WP. A primed constant I.V infusion of ¹³C₆-phenylalanine was used to determine MPS at baseline and in response to feeding (FED) and feeding-plus-exercise (FED-EX; 6 × 8 unilateral leg extensions; 75%1-RM). We quantified plasma insulin/AA concentrations, leg femoral blood flow (LBF)/muscle microvascular blood flow (MBF), and anabolic signalling via immunoblotting.

RESULTS

Plasma insulineamia and EAAemia were greater and more prolonged with WP than LEAA, although LEAA_6 peaked at similar levels to WP. Neither LEAA or WP modified LBF or MBF. FED increased MPS similarly in the LEAA_1.5, LEAA_6 and WP (P < 0.05) groups over 0-2 h, with MPS significantly higher than basal in the LEAA_6 and WP groups only over 0-4 h. However, FED-EX increased MPS similarly across all the groups from 0 to 4 h (P < 0.05). Only p-p70S6K1 increased with WP at 2 h in FED (P < 0.05), and at 2/4 h in FED-EX (P < 0.05).

CONCLUSIONS

In conclusion, LEAA_1.5, despite only providing 0.6 g of leucine, robustly (perhaps maximally) stimulated MPS, with negligible trophic advantage of greater doses of LEAA or even to 40 g WP. Highlighting that composition of EAA, in particular the presence of leucine rather than amount is most crucial for anabolism.

Comparison between parameters of muscle performance and inflammatory biomarkers of non-sarcopenic and sarcopenic elderly women

Background

Sarcopenia is a multifactorial geriatric syndrome with complex interrelationships. Increased plasma levels of inflammatory mediators increase the catabolic stimuli of the musculature, thereby causing a decrease in mass and muscular function.

Objective

The objective of this study was to compare the performance of the knee extensors test (by isokinetic dynamometer) and plasma levels of interleukin-6 (IL-6) and soluble receptors of tumor necrosis factor alpha (sTNFR1) between sarcopenics and non-sarcopenics community-dwelling elderly women residents of Brazil.

Material and methods

The diagnosis of sarcopenia included measurements of body composition (by densitometry with dual energy source of X-ray), handgrip strength (by Jamar^® dynamometer), and the usual gait velocity according to the recommendations of the European Working Group on Sarcopenia in Older People. In both sarcopenics and non-sarcopenics elderly women, we evaluated the muscle function by knee extensors test (using an isokinetic dynamometer Byodex System 4 Pro^®) at angular speeds of 60°/s and 180°/s) and also we evaluated the plasma concentrations of IL-6 and sTNFR1. Comparisons of muscle performance between groups were carried out using mixed factorial ANOVA with post hoc Bonferroni test; sTNFR1 and IL-6 variables were analyzed by applying Mann–Whitney U test.

Results

Statistical differences were observed between groups regarding muscle power (P=0.01), total work adjusted to body weight (P=0.01) at a rate of 180°/s, and plasma levels of sTNFR1 (P=0.01).

Conclusion

Sarcopenic elder women showed lower performance of the lower limbs, especially at a higher speed, predisposing these older women to greater vulnerability in functional activities that require agility and postural stability. Plasma levels of sTNFR1 were higher for non-sarcopenics elderlies. However, due to the observational nature of the study, it was impossible to infer causality among the variables surveyed.

Dietary protein intake in sarcopenic obese older women

Objective

To determine the prevalence of sarcopenia in a population of obese older women and to assess the effect of a diet moderately rich in proteins on lean mass in sarcopenic obese older women.

Materials and methods

A total of 1,030 females, >65 years old, body mass index >30 kg/m², were investigated about their nutritional status. Muscle mass (MM) was estimated according to the Janssen equation (MM =0.401× height²/resistance measured at 50 kHz +3.825× sex −0.071× age +5.102). Sarcopenia was defined according to the MM index, MM/height2 (kg/m²), as two standard deviations lower than the obesity-derived cutoff score (7.3 kg/m²). A food-frequency questionnaire was used to measure participants’ usual food intake during the previous 3 months. Moreover, a group of sarcopenic obese older women (n=104) was divided in two subgroups: the first (normal protein intake [NPI], n=50) administered with a hypocaloric diet (0.8 g/kg desirable body weight/day of proteins), and the second treated with a hypocaloric diet containing 1.2 g/kg desirable body weight/day of proteins (high protein intake [HPI], n=54), for 3 months. Dietary ingestion was estimated according to a daily food diary, self-administered, and three reports of nonconsecutive 24-hour recall every month during the follow-up.

Results

The 104 women were classified as sarcopenic. After dieting, significant reductions in body mass index were detected (NPI 30.7±1.3 vs 32.0±2.3 kg/m², HPI 30.26±0.90 vs 31.05±2.90 kg/m²; P<0.01 vs baseline). The MM index presented significant variations in the NPI as well as in the HPI sarcopenic group (NPI 6.98±0.1 vs 7.10±0.2 kg/m², HPI 7.13±0.4 vs 6.96±0.1 kg/m²; P<0.01 vs baseline).

Conclusion

A diet moderately rich in proteins was able to preserve MM in sarcopenic women. Therefore, adequate protein intake could contribute to the prevention of lean-mass loss associated with weight reduction in obese older people.

Bulbocavernosus muscle area measurement: a novel method to assess androgenic activity

Serum testosterone does not correlate with androgen tissue activity, and it is critical to optimize tools to evaluate such activity in males. Ultrasound measurement of bulbocavernosus muscle (BCM) was used to assess the relationship between the number of CAG repeats (CAGn) in the androgen receptor (AR) and the BCM size; the changes in the number of CAGn over age were also evaluated. Transperineal ultrasound measurement of the BCM was also performed. AR CAGn were determined by high performance liquid chromatography, and morning hormone levels were determined using immunoassays. Forty-eight men had CAG repeat analysis. Twenty-five were <30 years of age, mean 23.7 years (s.d. = 3.24) and 23 were >45 years of age, mean 53 years (s.d. = 5.58). The median CAGn was 21 (13-29). BCM area was greater when the number of CAGn were <18 as compared to the number of CAGn >24 (P = 0.04). There was a linear correlation between the number of CAGn and the BCM area R 2 = 16% (P = 0.01). In the 45 to 65-years-old group, a much stronger negative correlation (R 2 = 29%, P = 0.01) was noticed. In the 19 to 29-years-old group, no such correlation was found (R 2 = 4%, P = 0.36). In older men, the number of CAGn increased with age (R 2 = 32%, P = 0.01). The number of CAGn in the AR correlates with the area of the BCM. Ultrasound assessment of the BCM is an effective surrogate to evaluate end-organ activity of androgens. The number of CAGn may increase with age.

Intake of low-dose leucine-rich essential amino acids stimulates muscle anabolism equivalently to bolus whey protein in older women at rest and after exercise

Dysregulated anabolic responses to nutrition/exercise may contribute to sarcopenia; however, these characteristics are poorly defined in female populations. We determined the effects of two feeding regimes in older women (66 ± 2.5 yr; n = 8/group): bolus whey protein (WP-20 g) or novel low-dose leucine-enriched essential amino acids (EAA) [LEAA; 3 g (40% leucine)]. Using [(13)C6]phenylalanine infusions, we quantified muscle (MPS) and albumin (APS) protein synthesis at baseline and in response to both feeding (FED) and feeding plus exercise (FED-EX; 6 × 8 knee extensions at 75% 1-repetition maximum). We also quantified plasma insulin/AA concentrations, whole leg (LBF)/muscle microvascular blood flow (MBF), and muscle anabolic signaling by phosphoimmunoblotting. Plasma insulinemia and EAA/aemia were markedly greater after WP than LEAA (P < 0.001). Neither LEAA nor WP modified LBF in response to FED or FED-EX, whereas MBF increased to a similar extent in both groups only after FED-EX (P < 0.05). In response to FED, both WP and LEAA equally stimulated MPS 0-2 h (P < 0.05), abating thereafter (0-4 h, P > 0.05). In contrast, after FED-EX, MPS increased at 0-2 h and remained elevated at 0-4 h (P < 0.05) with both WP and LEAA. No anabolic signals quantifiably increased after FED, but p70 S6K1 Thr(389) increased after FED-EX (2 h, P < 0.05). APS increased similarly after WP and LEAA. Older women remain subtly responsive to nutrition ± exercise. Intriguingly though, bolus WP offers no trophic advantage over LEAA.

Sarcopenia: evaluation of different diagnostic criteria and its association with muscle strength and functional capacity

INTRODUCTION: Sarcopenia has been associated with increased morbidity and mortality in older people. However, there is still no consensus about the best diagnostic criteria for it. OBJECTIVE: This study aimed to evaluate different diagnostic criteria of sarcopenia and their relationship with muscle strength and functional capacity. METHODS: A cross-sectional study was carried out in Santa Maria-RS, Brazil. Body composition was measured by dual-energy X-ray absorptiometry (DXA). Physical performance was evaluated by the Timed-get-up-and-go test (TGUG). Muscle strength was measured with a handgrip dynamometer. The proposed criteria of sarcopenia were evaluated as follows: A) appendicular lean mass index (aLM/ht2), cutoffs 5.5 kg/m2, 2SD, 10th percentile, and 20th percentile of young reference; B) a linear regression model was used to adjust appendicular lean mass (aLM) for both height and fat mass, cutoff 20th percentile of elderly. RESULTS: In total, 104 women agreed to participate in the research, 39 young (20 to 40 years) and 65 elderly (over 60 years). The prevalence of sarcopenia varied from 0% to 17.2% according to the diagnostic criteria. Regarding muscle strength, the aLM/ht2 cutoff 10th percentile was the criterion with greater area under the ROC curve. However, there were no criteria with an area under the ROC curve greater than 0.5 when TGUG was the outcome. The reclassification showed that the criterion B reclassified 66.7% with normal grip strength as sarcopenic. CONCLUSION: Of these criteria, aLM/ht2 cutoff 10th percentile had stronger correlation with muscle strength.

Combined association of chronic disease and low skeletal muscle mass with physical performance in older adults in the Sarcopenia and Translational Aging Research in Taiwan (START) study

Background

Multiple chronic conditions and low skeletal muscle mass are common features of aging that are detrimental to physical performance. This study evaluates the simultaneous impact of these conditions on physical performance in older adults.

Methods

Five studies from 2003 to 2012 were pooled to include 2,398 adults aged ≥65 years with diagnosed chronic diseases measured by self-administered questionnaire. Low muscle mass was defined as an appendicular skeletal muscle mass index less than that of the sex-specific lowest quintile in the population of older adults. Poor physical performances were defined as the lowest quintile of grip strength and gait speed in the population of older adults and the slowest sex-specific 20% of Timed Up and Go (TUG) test at each study site. Chi-squared and logistic regression tests were applied for data analysis.

Results

Mean age of the study participants, of whom approximately 50% were men, was 74.3 years. Slow gait speed was nearly three times more likely to occur in the presence of low muscle mass coupled with chronic disease than in the absence of both factors after adjustment for study site, age, sex, education, marital status, body mass index, tobacco and alcohol use, and comorbidities. The independent effect of low muscle mass was generally stronger than that of each disease. Participants with more than two chronic diseases and low muscle mass were significantly more likely to perform poorly than those with no risk factors (odds ratio [OR] = 2.51 in patients with low grip strength, OR = 3.89 in patients with low gait speed, and OR = 3.67 in patients with poor TUG test scores, all P < 0 .05) after adjustment.

Conclusions

The combined association of chronic disease and low skeletal mass with physical performance was stronger than the effect of either factor alone.

The significance of body mass index in calculating the cut-off points for low muscle mass in the elderly: methodological issues

OBJECTIVES

Cut-off points (COPs) for appendicular lean mass (ALM) index, essential to define low muscle mass (LMM) in the elderly, have never been officially defined for Poland. The aim of the study was to establish them. Additionally, the significance of body mass index (BMI) for correctly defining the COPs in a young, healthy reference group was assessed.

METHODS

The study was composed of reference group (n = 1113) and the elderly group (n = 200). In all subjects, body composition was assessed by bioimpedance analysis, and ALM index was calculated. Next, COPs (kg/m(2)) were set up for the whole reference group and for particular subgroups with different BMIs separately. They were used to diagnose sarcopenia in the elderly.

RESULTS

COP for all young females was 5.37 (COP-F), while it was equal to 5.52 (COP-F2) when only those with a recommended BMI (18.50-24.99 kg/m(2)) were taken into consideration. For males, it was 7.32 and 7.29, respectively. Only 7% of elderly females had LMM based on COP-F and 15% had LMM based on COP-F2 (P < 0.05); for males, the percentages were 18% and 16%, respectively.

CONCLUSIONS

COPs for LMM for Poland are 5.52 kg/m(2) (females) and 7.29 kg/m(2) (males). The reference group BMI is an important factor in establishing COPs for low muscle mass.

The Official Positions of the International Society for Clinical Densitometry: body composition analysis reporting

Dual-energy x-ray absorptiometry (DXA) measurements of body composition increasingly are used in the evaluation of clinical disorders, but there has been little guidance on how to effectively report these measures. Uniformity in reporting of body composition measures will aid in the diagnosis of clinical disorders such as obesity, sarcopenia, and lipodystrophy. At the 2013 International Society for Clinical Densitometry Position Development Conference on body composition, the reporting section recommended that all DXA body composition reports should contain parameters of body mass index, bone mineral density, BMC, total mass, total lean mass, total fat mass, and percent fat mass. The inclusion of additional measures of adiposity and lean mass are optional, including visceral adipose tissue, appendicular lean mass index, android/gynoid percent fat ratio, trunk to leg fat mass ratio, lean mass index, and fat mass index. Within the United States, we recommend the use of the National Health and Nutrition Examination Survey 1999-2004 body composition dataset as an age-, gender-, and race-specific reference and to calibrate BMC in 4-compartment models. Z-scores and percentiles of body composition measures may be useful for clinical interpretation if methods are used to adjust for non-normality. In particular, DXA body composition measures may be useful for risk-stratification of obese and sarcopenic patients, but there needs to be validation of thresholds to define obesity and sarcopenia. To summarize, these guidelines provide evidence-based standards for the reporting and clinical application of DXA-based measures of body composition.