Mid-thigh Muscle Cross-sectional Area Research Articles

Neuromuscular Adaptations in Response to Disuse and Weight-Training Rehabilitation are Enhanced in Resistance Trained Individuals

INTRODUCTION: Lower-limb disuse from immobilization results in a decrease in muscle strength, volume, and function. However, muscle atrophy from disuse does not entirely account for the observed strength and functional declines. Additionally, prior engagement in resistance training (RT) has been linked to the preservation of muscular strength and neuromuscular function. Therefore, the purpose of this study was to assess the influence of a single-leg immobilization protocol, followed by structured RT rehabilitation protocol, on muscle strength, volume, and neural activation in healthy young adults with and without previous strength training experience. Methods: Participants (10 Trained (T): 8 men, 2 women; 11 Untrained (UT): 8 men, 3 women) underwent 2-weeks of left-knee immobilization at 90° knee-flexion with a hinged immobilizer knee-brace. Participants were given a pair of axillary crutches for ambulation during this time. Following immobilization, all participants underwent an 8-week structured RT rehabilitation protocol. Participants visited the laboratory for three testing sessions (baseline test on Day 0; post-immobilization at the end of week 2; and post-RT rehab at the end of week 10). Maximal knee extensor isometric strength at 45°was quantified using an isokinetic dynamometer (Biodex). Voluntary muscle activation was quantified as the root mean square (RMS) of the interference electromyography (EMG) signals derived from two indwelling fine-wire electrodes in the vastus-lateralis muscle. Additionally, a continuous wavelet transform (CWT) was performed on the EMG to determine amplitude versus frequency characteristics of the signals and how this amplitude varied with time in the 13-30 (beta) and 30-60 (piper) Hz bands. Mid-thigh muscle cross-sectional area (mCSA) and density were also quantified using peripheral quantitative computed tomography (pQCT) during all testing sessions. Results: The T group was significantly stronger (p=0.019), had greater muscle density (p=0.005) and mid-thigh mCSA (p<0.001) across all sessions when compared with the UT group. However, there were no significant time or interaction effects for strength or muscle density losses (p>0.05). While both groups demonstrated increased muscle activation across sessions (RMS: p=0.04; CWT: p=0.021), the T group demonstrated a greater increase in the neural drive from baseline to week 10 when compared with the UT group (RMS: p= 0.002; CWT: p=0.027). CONCLUSION: In younger adults with or without prior strength training experience, we find that losses in knee extensor isometric strength, muscle density, and mid-thigh mCSA are minimal following a 2-week immobilization protocol. However, certain neuromuscular adaptations during immobilization and following weight-training rehabilitation are enhanced to a greater degree in those with prior training, which is seemingly indicative of greater synchrony in descending cortical drive and motor unit recruitment. These latter findings warrant continued investigation using additional innovative methodologies (e.g., fMRI, TMS, etc.) for assessing the mechanisms underlying the effects of prehab protocols on neuromuscular adaptations. PGRF and Nix family foundation scholarship to Marina Meyer. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Associations between adiponectin and leptin levels and skeletal muscle mass and myosteatosis in older adults: The Shimanami Health Promoting Program study

Identifying plasma molecules associated with skeletal muscle properties can elucidate the pathophysiology of sarcopenia. Because adipocytokines are a promising candidate marker, the current study aimed to clarify the possible associations between adiponectin and leptin levels and mid-thigh muscle cross-sectional area and mean attenuation value, which are indices of muscle mass and fat deposition in muscle, respectively. The current study included 1440 older Japanese adults (mean age 69.3 years). Mid-thigh skeletal muscle cross-sectional area and mean attenuation value were evaluated through computed tomography scan. A low attenuation value showed a greater fat deposition in muscle. Circulating adiponectin and leptin levels were assessed using blood specimens collected during the baseline investigation. Plasma leptin level was inversely correlated with muscle cross-sectional area, but not with attenuation value. The association with cross-sectional area was independent of possible confounding factors including body size (Q1: reference; Q2: β = -0.032, P = 0.033; Q3: β = -0.064, P < 0.001; Q4: β = -0.111, P < 0.001). In contrast, adiponectin level was independently and inversely associated with attenuation value (Q1: reference; Q2: β = -0.044, P = 0.122; Q3: β = -0.080, P = 0.006; Q4: β = -0.159, P < 0.001), but not with cross-sectional area. These associations between adipocytokine levels and muscle properties were independent of abdominal fat area and insulin resistance. There were adiposity- and insulin resistance-independent associations between adipocytokines levels and skeletal muscle mass and fat deposition in muscle, suggesting an involvement of adipocytokines in muscle properties. Geriatr Gerontol Int 2023; 23: 444-449.

Bioimpedance phase angle is independently associated with myosteatosis: The Shizuoka study

Phase angle (PhA) calculated from the resistance and reactance measured using a bioimpedance device was suggested to represent the degree of fat deposition in muscle (myosteatosis), though no direct evidence is available. We aimed to clarify the possible association between PhA and skeletal muscle myosteatosis in community-dwelling middle-aged to older adults. Participants consisted of 424 Japanese (aged ≥50 years). Leg PhA and skeletal muscle mass index (SMI) were obtained by bioelectrical impedance analysis. The mean attenuation values and cross-sectional area of the mid-thigh skeletal muscle were calculated from computed tomography images and considered as indexes of myosteatosis and skeletal muscle mass, respectively. Leg PhA was positively associated with SMI, and cross-sectional area and mean attenuation value at mid-thigh. Multiple regression analysis adjusted for possible covariates identified leg PhA (β=0.214) and SMI (β=0.260) as independent factors of mid-thigh muscle cross-sectional area (P<0.001), while leg PhA (β=0.349, P<0.001) but not SMI (P=0.645) was associated with mean attenuation value. Similar results were observed in the analysis in the older (≥65 years) subpopulation. The combination of low SMI and low leg PhA showed stepwise association with cross-sectional area, while only individuals with low leg PhA had lower mean attenuated value. Leg PhA was independently associated with mean attenuated value of the mid-thigh skeletal muscle, suggesting that the assessment of PhA in combination with SMI could provide additional information for the evaluation of muscle properties.

Functional clinical impairments and frailty in interstitial lung disease patients.

BackgroundPatients with interstitial lung disease (ILD) often present with persistent dyspnoea and reduced exercise capacity and quality of life (QoL), but their functional limitation in relation to their frailty status remains unclear. We thus aimed to compare exercise tolerance, functional mobility, and muscle function and composition between ILD participants and healthy subjects and according to their frailty status.MethodsA total of 36 ILD participants and 15 heathy subjects performed a 6-min walk test, a 1-min sit-to-stand test, a Short Physical Performance Battery test, a hand grip test and complete quadriceps function testing. Patient-related impacts were assessed via questionnaires. Muscle composition was obtained using noncontrast computed tomography scans. The frailty status of patients with ILD was determined using the Fried frailty phenotype assessment.ResultsCompared with control subjects, ILD participants exhibited significantly lower performance in every exercise and functional capacity test, higher dyspnoea and depression scores, and worse QoL. In ILD participants, the same observations were noted for the frail subgroup compared with the robust subgroup. No differences in muscle function and composition were observed between the ILD and control group, but mid-thigh muscle cross-sectional area and skeletal muscle index were significantly reduced in frail ILD participants.ConclusionsILD patients present reduced exercise tolerance and functional capacity, and have decreased health-related QoL, when compared with healthy subjects. Physical frailty seems to be associated with worse clinical status, exercise tolerance, muscle and functional impairment, and decreased QoL. The 1-min sit-to-stand test may be a good discriminatory test for frailty status in ILD patients.

Utilization of Mid-Thigh Magnetic Resonance Imaging to Predict Lean Body Mass and Knee Extensor Strength in Obese Adults.

Purpose:To train and test a machine learning model to automatically measure mid-thigh muscle cross-sectional area (CSA) to provide rapid estimation of appendicular lean mass (ALM) and predict knee extensor torque of obese adults.Methods:Obese adults [body mass index (BMI) = 30–40 kg/m2, age = 30–50 years] were enrolled for this study. Participants received full-body dual-energy X-ray absorptiometry (DXA), mid-thigh MRI, and completed knee extensor and flexor torque assessments via isokinetic dynamometer. Manual segmentation of mid-thigh CSA was completed for all MRI scans. A convolutional neural network (CNN) was created based on the manual segmentation to develop automated quantification of mid-thigh CSA. Relationships were established between the automated CNN values to the manual CSA segmentation, ALM via DXA, knee extensor, and flexor torque.Results:A total of 47 obese patients were enrolled in this study. Agreement between the CNN-automated measures and manual segmentation of mid-thigh CSA was high (>0.90). Automated measures of mid-thigh CSA were strongly related to the leg lean mass (r = 0.86, p < 0.001) and ALM (r = 0.87, p < 0.001). Additionally, mid-thigh CSA was strongly related to knee extensor strength (r = 0.76, p < 0.001) and moderately related to knee flexor strength (r = 0.48, p = 0.002).Conclusion:CNN-measured mid-thigh CSA was accurate compared to the manual segmented values from the mid-thigh. These values were strongly predictive of clinical measures of ALM and knee extensor torque. Mid-thigh MRI may be utilized to accurately estimate clinical measures of lean mass and function in obese adults.

Myofibril and Mitochondrial Area Changes in Type I and II Fibers Following 10 Weeks of Resistance Training in Previously Untrained Men.

Resistance training increases muscle fiber hypertrophy, but the morphological adaptations that occur within muscle fibers remain largely unresolved. Fifteen males with minimal training experience (24±4years, 23.9±3.1kg/m2 body mass index) performed 10weeks of conventional, full-body resistance training (2× weekly). Body composition, the radiological density of the vastus lateralis muscle using peripheral quantitative computed tomography (pQCT), and vastus lateralis muscle biopsies were obtained 1week prior to and 72h following the last training bout. Quantification of myofibril and mitochondrial areas in type I (positive for MyHC I) and II (positive for MyHC IIa/IIx) fibers was performed using immunohistochemistry (IHC) techniques. Relative myosin heavy chain and actin protein abundances per wet muscle weight as well as citrate synthase (CS) activity assays were also obtained on tissue lysates. Training increased whole-body lean mass, mid-thigh muscle cross-sectional area, mean and type II fiber cross-sectional areas (fCSA), and maximal strength values for leg press, bench press, and deadlift (p<0.05). The intracellular area occupied by myofibrils in type I or II fibers was not altered with training, suggesting a proportional expansion of myofibrils with fCSA increases. However, our histological analysis was unable to differentiate whether increases in myofibril number or girth occurred. Relative myosin heavy chain and actin protein abundances also did not change with training. IHC indicated training increased mitochondrial areas in both fiber types (p=0.018), albeit CS activity levels remained unaltered with training suggesting a discordance between these assays. Interestingly, although pQCT-derived muscle density increased with training (p=0.036), suggestive of myofibril packing, a positive association existed between training-induced changes in this metric and changes in mean fiber myofibril area (r=0.600, p=0.018). To summarize, our data imply that shorter-term resistance training promotes a proportional expansion of the area occupied by myofibrils and a disproportional expansion of the area occupied by mitochondria in type I and II fibers. Additionally, IHC and biochemical techniques should be viewed independently from one another given the lack of agreement between the variables assessed herein. Finally, the pQCT may be a viable tool to non-invasively track morphological changes (specifically myofibril density) in muscle tissue.

Muscle transcriptional networks linked to resistance exercise training hypertrophic response heterogeneity.

The skeletal muscle hypertrophic response to resistance exercise training (RT) is highly variable across individuals. The molecular underpinnings of this heterogeneity are unclear. This study investigated transcriptional networks linked to RT-induced muscle hypertrophy, classified as 1) predictive of hypertrophy, 2) responsive to RT independent of muscle hypertrophy, or 3) plastic with hypertrophy. Older adults (n = 31, 18 F/13 M, 70 ± 4 yr) underwent 14-wk RT (3 days/wk, alternating high-low-high intensity). Muscle hypertrophy was assessed by pre- to post-RT change in mid-thigh muscle cross-sectional area (CSA) [computed tomography (CT), primary outcome] and thigh lean mass [dual-energy X-ray absorptiometry (DXA), secondary outcome]. Transcriptome-wide poly-A RNA-seq was performed on vastus lateralis tissue collected pre- (n = 31) and post-RT (n = 22). Prediction networks (using only baseline RNA-seq) were identified by weighted gene correlation network analysis (WGCNA). To identify Plasticity networks, WGCNA change indices for paired samples were calculated and correlated to changes in muscle size outcomes. Pathway-level information extractor (PLIER) was applied to identify Response networks and link genes to biological annotation. Prediction networks (n = 6) confirmed transcripts previously connected to resistance/aerobic training adaptations in the MetaMEx database while revealing novel member genes that should fuel future research to understand the influence of baseline muscle gene expression on hypertrophy. Response networks (n = 6) indicated RT-induced increase in aerobic metabolism and reduced expression of genes associated with spliceosome biology and type-I myofibers. A single exploratory Plasticity network was identified. Findings support that interindividual differences in baseline gene expression may contribute more than RT-induced changes in gene networks to muscle hypertrophic response heterogeneity. Code/Data: https://github.com/kallavin/MASTERS_manuscript/tree/master.

The Effects of a 6-Week Controlled, Hypocaloric Ketogenic Diet, With and Without Exogenous Ketone Salts, on Body Composition Responses.

Background: Ketogenic diets (KDs) that elevate beta-hydroxybutyrate (BHB) promote weight and fat loss. Exogenous ketones, such as ketone salts (KS), also elevate BHB concentrations with the potential to protect against muscle loss during caloric restriction. Whether augmenting ketosis with KS impacts body composition responses to a well-formulated KD remains unknown.Purpose: To explore the effects of energy-matched, hypocaloric KD feeding (<50 g carbohydrates/day; 1.5 g/kg/day protein), with and without the inclusion of KS, on weight loss and body composition responses.Methods: Overweight and obese adults were provided a precisely defined hypocaloric KD (~75% of energy expenditure) for 6 weeks. In a double-blind manner, subjects were randomly assigned to receive ~24 g/day of a racemic BHB-salt (KD + KS; n = 12) or placebo (KD + PL; n = 13). A matched comparison group (n = 12) was separately assigned to an isoenergetic/isonitrogenous low-fat diet (LFD). Body composition parameters were assessed by dual x-ray absorptiometry and magnetic resonance imaging.Results: The KD induced nutritional ketosis (>1.0 mM capillary BHB) throughout the study (p < 0.001), with higher fasting concentrations observed in KD + KS than KD + PL for the first 2 weeks (p < 0.05). There were decreases in body mass, whole body fat and lean mass, mid-thigh muscle cross-sectional area, and both visceral and subcutaneous adipose tissues (p < 0.001), but no group differences between the two KDs or with the LFD. Urine nitrogen excretion was significantly higher in KD + PL than LFD (p < 0.01) and trended higher in KD + PL compared to KD + KS (p = 0.076), whereas the nitrogen excretion during KD + KS was similar to LFD (p > 0.05).Conclusion: Energy-matched hypocaloric ketogenic diets favorably affected body composition but were not further impacted by administration of an exogenous BHB-salt that augmented ketosis. The trend for less nitrogen loss with the BHB-salt, if manifested over a longer period of time, may contribute to preserved lean mass.

The impact of disease-related immobilization on thigh muscle mass and strength in older hospitalized patients

BackgroundWe assessed the quantitative changes in muscle mass and strength during 2 weeks of hospitalization in immobile and mobile acutely ill hospitalized older adults.MethodsForty-one patients (82.4 ± 6.6 years, 73.0% females) participated in this prospective longitudinal observational study. Mobility status was defined according to walking ability as described in the Barthel-Index. Functional status, including handgrip strength and isometric knee-extension strength, and mid-thigh magnetic resonance imaging (MRI) measurements of cross-sectional area (CSA) were conducted on admission and at discharge.ResultsTwenty-two participants (54%) were immobile and 19 (46%) mobile. In all, 54.0 and 12.0% were at risk of malnutrition and malnourished, respectively. The median time between baseline and follow-up for MRI scans were 13 days in mobile and immobile participants (P = 0.072). Mid-thigh muscle and subcutaneous fat CSA significantly decreased by 3.9cm2 (5.0%, P = 0.002) and 5.3cm2 (5.7%, P = 0.036) during hospitalization whereas intermuscular fat remained unchanged in immobile subjects. No significant changes were observed in mobile patients. In a regression analysis, mobility was the major independent risk factor for changes in mid-thigh muscle CSA as a percentage of initial muscle area (P = 0.022) whereas other variables such as age (P = 0.584), BMI (P = 0.879), nutritional status (P = 0.835) and inflammation (P = 0.291) were not associated with muscle mass changes. There was a significant decrease in isometric knee extension strength (P = 0.002) and no change in handgrip strength (P = 0.167) in immobile patients whereas both parameters increased significantly over time in mobile patients (P = 0.048 and P = 0.012, respectively).ConclusionsTwo weeks of disease-related immobilization result in a significant loss of thigh muscle mass and muscle strength in older patients with impaired mobility. Concomitantly, there was a significant reduction of subcutaneous adipose tissue in immobile older hospitalized patients whereas no changes were observed in intermuscular fat among these patients. These data highlight the importance of mobility support in maintaining muscle mass and function in older hospitalized patients.

The Relationship Between Intermuscular Fat and Physical Performance Is Moderated by Muscle Area in Older Adults.

Age-related deposition of fat in skeletal muscle is associated with functional limitations. Skeletal muscle fat may be present in people with preserved muscle mass or accompanied by muscle wasting. However, it is not clear if the association between muscle fat deposition and physical performance is moderated by muscle mass. To determine whether the association between midthigh intermuscular fat and physical performance is moderated by muscle area. We performed a cross-sectional analysis of the Health, Aging, and, Body Composition (ABC) study data collected in 2002-2003 (n = 1897, women: 52.2%). Midthigh muscle cross-sectional area (by computed tomography) and physical performance measures were compared across quartiles of intermuscular fat absolute area. Moderation analysis was performed to determine the conditional effect of intermuscular fat on physical performance as a function of muscle area. Conditional effects were evaluated at three levels of muscle area (mean and ± 1 standard deviation [SD]; 213.2 ± 53.2 cm2). Simple slope analysis showed that the negative association between intermuscular fat area (cm2) and leg strength (N·m) was of greater magnitude (beta coefficient [b], 95% confidence interval [CI] = -0.288 [-0.427, -0.148]) in participants with greater muscle area (ie, 1 SD above the mean) compared to those with lower muscle area (ie, at mean [b = -0.12 {-0.248, 0.008}] or 1 SD below the mean [b = 0.048 {-0.122, 0.217}]). Similarly, the negative association of intermuscular fat with 400-m walk speed (m/s) and chair stand (seconds) was greater in those with higher muscle areas (p < .001) compared to those with lower muscle areas. The association between higher intermuscular fat area and impaired physical function in aging is moderated by muscle area.

The Impact of Malnutrition on Acute Muscle Wasting in Frail Older Hospitalized Patients.

Very little is known about the effect of malnutrition on short-term changes of body composition, particularly muscle, among older hospitalized patients. We sought to investigate the association of malnutrition as assessed by the Global Leadership Initiative on Malnutrition (GLIM) criteria with changes of thigh muscle mass and muscle strength among older patients during hospitalization. Forty-one patients (age range 66–97 years, 73% female) participated in this prospective longitudinal observational study. Nutritional status was evaluated using the GLIM criteria on admission and at discharge. Functional status and mid-thigh magnetic resonance imaging (MRI) measurements of cross-sectional area (CSA) were conducted on admission and before discharge. In all, 17% were malnourished and 83% had no malnutrition. Mean mid-thigh muscle CSA declined by 7.0 cm2 (−9%) in malnourished patients during hospitalization (p = 0.008) and remained unchanged among non-malnourished patients (−1%, p = 0.390). Mean mid-thigh CSA of subcutaneous and intermuscular fat did not change significantly during hospitalization in both groups. Malnourished subjects lost 10% of handgrip strength (−1.8 kg) and 12% of knee extension strength (−1.5 kg) during hospitalization. However, the magnitude of both changes did not differ between groups. In a stepwise multiple regression analysis, malnutrition and changes in body weight during hospitalization were the major independent risk factors for the reduction of muscle CSA. Malnutrition according to the GLIM criteria was significantly and independently associated with acute muscle wasting in frail older patients during 2-week hospitalization.

Effects of concurrent exercise training on muscle dysfunction and systemic oxidative stress in older people with COPD.

Oxidative stress is associated with disease severity and limb muscle dysfunction in COPD. Our main goal was to assess the effects of exercise training on systemic oxidative stress and limb muscle dysfunction in older people with COPD. Twenty-nine outpatients with COPD (66-90years) were randomly assigned to a 12-week exercise training (ET; high-intensity interval training (HIIT) plus power training) or a control (CT; usual care) group. We evaluated mid-thigh muscle cross-sectional area (CSA; computed tomography); vastus lateralis (VL) muscle thickness, pennation angle, and fascicle length (ultrasonography); peak VO2 uptake (VO2peak ) and work rate (Wpeak ) (incremental cardiopulmonary exercise test); rate of force development (RFD); maximal muscle power (Pmax ; force-velocity testing); systemic oxidative stress (plasma protein carbonylation); and physical performance and quality of life. ET subjects experienced changes in mid-thigh muscle CSA (+4%), VL muscle thickness (+11%) and pennation angle (+19%), VO2peak (+14%), Wpeak (+37%), RFD (+32% to 65%), Pmax (+38% to 51%), sit-to-stand time (-24%), and self-reported health status (+20%) (all P<0.05). No changes were noted in the CT group (P>0.05). Protein carbonylation decreased among ET subjects (-27%; P<0.05), but not in the CT group (P>0.05). Changes in protein carbonylation were associated with changes in muscle size and pennation angle (r=-0.44 to -0.57), exercise capacity (r=-0.46), muscle strength (r=-0.45), and sit-to-stand performance (r=0.60) (all P<0.05). The combination of HIIT and power training improved systemic oxidative stress and limb muscle dysfunction in older people with COPD. Changes in oxidative stress were associated with exercise-induced structural and functional adaptations.

High Inter-muscular Fat Is Associated with Poor Mobility Function in Older Adults, Only When Accompanied by Low Muscle Area (P01-026-19)

ObjectivesTo determine whether the associations between thigh inter-muscular-fat area, anthropometric characteristics and physical performance varies in old adults with low vs. high thigh muscle cross-sectional area. MethodsCross-sectional analysis of year 6 data from 1903 participants (52.2% women) of the Health ABC study aged 74–85y. Mid-thigh muscle composition (by CT), body composition (DXA) and physical performance were compared across quartiles of mid-thigh inter-muscular fat area. General linear model univariate analysis was used to study the associations between inter-muscular fat area and physical function according to low or high mid-thigh muscle cross-sectional area (using the 50th percentile). ResultsIn participants with low mid-thigh muscle area, there was a threshold effect in which high inter-muscular fat was related to poor mobility function after the 2nd quartile (>23.7 cm2 in men and >21.3 cm2 in women). While, in participants with high mid-thigh muscle area, high inter-muscular fat was not associated with poor mobility function. Inter-muscular fat had no significant association with isokinetic knee strength in participants with either low or high muscle area. However, across all inter-muscular fat conditions, participants with low muscle area had lower leg strength than those with high muscle area. ConclusionsThe negative effects of inter-muscular fat in aging are greatly influenced by the presence of concurrent low muscle mass. Funding SourcesNIA/NIH.

Dietary protein intake is not associated with 5-y change in mid-thigh muscle cross-sectional area by computed tomography in older adults: the Health, Aging, and Body Composition (Health ABC) Study

ABSTRACTBackgroundA higher protein intake is suggested to preserve muscle mass during aging and may therefore reduce the risk of sarcopenia.ObjectivesWe explored whether the amount and type (animal or vegetable) of protein intake were associated with 5-y change in mid-thigh muscle cross-sectional area (CSA) in older adults (n = 1561).MethodsProtein intake was assessed at year 2 by a Block food-frequency questionnaire in participants (aged 70–79 y) of the Health, Aging, and Body Composition (Health ABC) Study, a prospective cohort study. At year 1 and year 6 mid-thigh muscle CSA in square centimeters was measured by computed tomography. Multiple linear regression analysis was used to examine the association between energy-adjusted protein residuals in grams per day (total, animal, and vegetable protein) and muscle CSA at year 6, adjusted for muscle CSA at year 1 and potential confounders including prevalent health conditions, physical activity, and 5-y change in fat mass.ResultsMean (95% CI) protein intake was 0.90 (0.88, 0.92) g · kg–1 · d–1 and mean (95% CI) 5-y change in muscle CSA was −9.8 (−10.6, −8.9) cm2. No association was observed between energy-adjusted total (β = −0.00; 95% CI: −0.06, 0.06 cm2; P = 0.982), animal (β = −0.00; 95% CI: −0.06, 0.05 cm2; P = 0.923), or plant (β = +0.07; 95% CI: −0.06, 0.21 cm2; P = 0.276) protein intake and muscle CSA at year 6, adjusted for baseline mid-thigh muscle CSA and potential confounders.ConclusionsThis study suggests that a higher total, animal, or vegetable protein intake is not associated with 5-y change in mid-thigh muscle CSA in older adults. This conclusion contradicts some, but not all, previous research. This trial was registered at www.trialregister.nl as NTR6930.

Hypogonadism in chronic obstructive pulmonary disease (COPD): Risk factors

Bacground/Aim. Chronic obstructive pulmonary disease (COPD) is the leading cause of morbidity and mortality in pulmonary pathology. However, apart from its own pulmonary manifestations, this disease is also characterized by systemic effects, including hypogonadism which is described especially in the group of men with COPD. The aim of this study was to evaluate risk factors for hypogonadism in men with COPD. Methods. The study included 96 male patients with COPD in stable phase of the disease. All patients were checked for concentration of free testosterone in serum, markers of systemic inflammation, tumor necrosis factor-? (TNF-?), interleukin-1? (IL-1?) and C reactive protein (CRP), pulmonary function test, gas exchange parameters, a 6-minute walk test (6MWT), nutritional status and condition of skeletal muscle (midthigh muscle cross-sectional area ? MTCSA using computed tomography). Results. Decreased value of free testosterone was found in 37.5% of the patients. In the group with hypogonadism (free testosterone &lt; 4.5 pg/mL), we found significantly increased serum concentration of TNF-? (5.88 ? 3.21 vs. 3.16 ? 2.53 pg/mL; p &lt; 0.05), significantly lower MTSCA (68.2 ? 18.72 vs. 91.1 ? 21.4 cm2; p &lt; 0.05) and the 6MWT (268.33 ? 32.35 vs. 334.25 ? 43.25 m; p &lt; 0.05). Lung function, gas exchange markers and body mass index (BMI) were similar in both groups. The multivariate regression analysis singled out serum value of TNF-? as an independent predictor of serum concentrations of free testosterone (B = -0.157; 95% confidence interval: -0.262?0.053). Conclusion. In our analysis we found that TNF-? as a marker of systemic inflammation is an independent predictor of the presence of hypogonadism in the patients with COPD. Our results indicate that hypogonadism predisposes to skeletal muscle wasting and exercise intolerance in male COPD patients.

OR30: A Higher Protein Intake is not Associated with 5-Year Change in Mid-Thigh Muscle Cross-Sectional Area by Computed Tomography in Older Adults: the Health, Aging, and Body Composition (Health ABC) Study

OR30: A Higher Protein Intake is not Associated with 5-Year Change in Mid-Thigh Muscle Cross-Sectional Area by Computed Tomography in Older Adults: the Health, Aging, and Body Composition (Health ABC) Study

Anthropometric prediction of skeletal muscle cross-sectional area in persons with spinal cord injury.

Finding an accurate and affordable method to quantify muscle size following spinal cord injury (SCI) could provide benefits clinically and in research settings. The purpose of this study was to validate the use of anthropometric measurements vs. magnetic resonance imaging (MRI) to evaluate muscle cross-sectional area (CSA) and develop a field equation to predict muscle CSA specific to the SCI population. Twenty-two men with chronic (>1 yr) motor complete SCI participated in the current study. Anthropometric measurements, including midthigh circumference and anterior skinfold thickness (SFT), were taken on the right thigh. The anthropometric muscle cross-sectional area (muscle CSAanthro) was predicted using the following equation: muscle CSAanthro = π[r - (SFT/2)]2, where r = thigh circumference/2π. MRI analysis yielded whole thigh CSA (thigh CSAMRI), midthigh muscle CSA (muscle CSAMRI), midthigh absolute muscle CSA after subtracting intramuscular fat and bone (muscle CSA-IMFMRI), subcutaneous adipose tissue (SATT) measured at one site as well as at four sites, and bone CSA. Anthropometric measurements were correlated to the thigh CSAMRI [r2 = 0.90, standard error of the estimate (SEE) = 17.6 cm2, P < 0.001]. Muscle CSAanthro was correlated to muscle CSAMRI (r2 = 0.78, SEE = 16.6 cm2, P < 0.001) and muscle CSA-IMFMRI (r2 = 0.75, SEE = 17.6 cm2, P < 0.001). A single SFT was correlated to the polar four-site SATT (r2 = 0.78, SEE = 0.37 cm, P < 0.001). The average femur CSA and average IMF CSA derived from MRI led to the following field equation: muscle CSApredicted = π[(Thighcircum/2π) - (SFT/2)]2 - 23.2. Anthropometric measurements of muscle CSA exhibited a good agreement with the gold standard MRI method and led to the development of a field equation for clinical use after accounting for bone and IMF.NEW & NOTEWORTHY This study used anthropometric measurements and magnetic resonance imaging (MRI) to evaluate muscle cross-sectional area (CSA) and developed a field equation to predict thigh muscle CSA specific to the spinal cord-injured (SCI) population. Anthropometric measurements were correlated to the whole thigh CSA and muscle CSA as measured by MRI. The correlations led to the development of a SCI-specific field equation that accounted for intramuscular fat and bone areas.

Validity of linear encoder measurement of sit-to-stand performance power in older people

ObjectiveTo investigate construct validity of linear encoder measurement of sit-to-stand performance power in older people by showing associations with relevant functional performance and physiological parameters. DesignCross-sectional study. SettingMovement laboratory of a geriatric rehabilitation clinic. ParticipantsEighty-eight community-dwelling, cognitively unimpaired older women (mean age 78 years). Main outcome measuresSit-to-stand performance power and leg power were assessed using a linear encoder and the Nottingham Power Rig, respectively. Gait speed was measured on an instrumented walkway. Maximum quadriceps and hand grip strength were assessed using dynamometers. Mid-thigh muscle cross-sectional area of both legs was measured using magnetic resonance imaging. ResultsAssociations of sit-to-stand performance power with power assessed by the Nottingham Power Rig, maximum gait speed and muscle cross-sectional area were r=0.646, r=0.536 and r=0.514, respectively. A linear regression model explained 50% of the variance in sit-to-stand performance power including muscle cross-sectional area (p=0.001), maximum gait speed (p=0.002), and power assessed by the Nottingham Power Rig (p=0.006). ConclusionsConstruct validity of linear encoder measurement of sit-to-stand power was shown at functional level and morphological level for older women. This measure could be used in routine clinical practice as well as in large-scale studies. Clinical Trial Registration NumberDRKS00003622.

Quantitative analysis of skeletal muscle mass in patients with rheumatic diseases under glucocorticoid therapy – Comparison among bioelectrical impedance analysis, computed tomography, and magnetic resonance imaging

Objectives. To determine the availability of bioelectrical impedance analysis (BIA), computed tomography (CT), and magnetic resonance imaging (MRI) for measurement of skeletal muscle mass in patients with rheumatic diseases and quantitatively assess skeletal muscle loss after glucocorticoid (GC) treatment.Methods. The data from 22 patients with rheumatic diseases were retrospectively obtained. The muscle mass of body segments was measured with a BIA device in terms of skeletal muscle mass index (SMI). Cross-sectional area (CSA) was obtained from CT and MRI scans at the mid-thigh level using the image analysis program. We further assessed the data of three different measurements before and after GC treatment in 7 patients with rheumatic diseases.Results. SMI of whole body was significantly correlated with estimated muscle volume and mid-thigh muscle CSA with CT and MRI (p < 0.01). Significant correlations between SMI and mid-thigh muscle CSA of each leg were also found (p < 0.01). All the three measurements were negatively correlated with GC dosage (p < 0.01). Significant decline in mid-thigh muscle CSA with CT and MRI was found after GC treatment in 7 patients (p < 0.02). Those patients showed significant decline in SMI of whole body after GC treatment, but not in SMI of each leg. On the other hand, significant correlations between mid-thigh muscle CSA with CT and MRI were found before and after GC treatment (p < 0.01).Conclusions. GC-related skeletal muscle loss could be quantitatively assessed with BIA, CT, or MRI in patients with rheumatic diseases, and CT and MRI appeared to be more accurate than BIA.

Obesity in chronic obstructive pulmonary disease: is fatter really better?

Overweight⁄obesity is associated with longer survival in chronically ill patients, a phenomenon referred to as the 'obesity paradox'. To investigate whether the obesity paradox in patients with chronic obstructive pulmonary disease (COPD) is due to fat accumulation or confounding factors. A total of 190 patients with stable COPD who underwent a mean (± SD) follow-up period of 72±34 months were enrolled. Anthropometry, pulmonary function tests, midthigh muscle cross-sectional area obtained using computed tomography (MTCSACT), arterial blood gas and exercise testing data were measured at baseline. Patients were categorized into two subgroups according to body mass index (BMI) <25 kg⁄m2 or ≥25 kg⁄m2 (normal and overweight⁄obese, respectively). Seventy-two patients (38%) died during the follow-up period. Survival tended to be better in the overweight⁄obese patients but this difference did not reach statistical significance. Overweight⁄obese patients had better lung function and a larger MTCSACT than those with normal BMI (P<0.001). Overweight⁄obese patients also had a significantly higher peak work rate than patients with normal BMI (P<0.001). PaO2 and PaCO2 were not significantly different in the two groups. When adjusted for PaCO2, peak work rate and MTCSACT, the tendency for improved survival in overweight⁄obese patients disappeared. In fact, when these variables were considered in the survival analysis, patients with lower BMI tended to have better survival. These results suggest that important confounders, such as hypercapnia, exercise capacity and muscle mass, should be considered when interpreting the association between increased BMI and survival in patients with COPD.