Muscle Quality, Strength, and Lower Extremity Physical Performance in the Baltimore Longitudinal Study of Aging

Comparison of Body Composition, Muscle Strength and Cardiometabolic Profile in Children with Prader-Willi Syndrome and Non-Alcoholic Fatty Liver Disease: A Pilot Study

Syndromic and non-syndromic obesity conditions in children, such as Prader-Willi syndrome (PWS) and non-alcoholic fatty liver disease (NAFLD), both lower quality of life and increase risk for chronic health complications, which further increase health service utilization and cost. In a pilot observational study, we compared body composition and muscle strength in children aged 7−18 years with either PWS (n = 9), NAFLD (n = 14), or healthy controls (n = 16). Anthropometric and body composition measures (e.g., body weight, circumferences, skinfolds, total/segmental composition, and somatotype), handgrip strength, six minute-walk-test (6MWT), physical activity, and markers of liver and cardiometabolic dysfunction (e.g., ALT, AST, blood pressure, glucose, insulin, and lipid profile) were measured using standard procedures and validated tools. Genotyping was determined for children with PWS. Children with PWS had reduced lean body mass (total/lower limb mass), lower handgrip strength, 6MWT and increased sedentary activity compared to healthy children or those with NAFLD (p < 0.05). Children with PWS, including those of normal body weight, had somatotypes consistent with relative increased adiposity (endomorphic) and reduced skeletal muscle robustness (mesomorphic) when compared to healthy children and those with NAFLD. Somatotype characterizations were independent of serum markers of cardiometabolic dysregulation but were associated with increased prevalence of abnormal systolic and diastolic blood pressure Z-scores (p < 0.05). Reduced lean body mass and endomorphic somatotypes were associated with lower muscle strength/functionality and sedentary lifestyles, particularly in children with PWS. These findings are relevant as early detection of deficits in muscle strength and functionality can ensure effective targeted treatments that optimize physical activity and prevent complications into adulthood.

Linoleic Acid Intake and Physical Function: Pilot Results from the Health ABC Energy Expenditure Sub-Study

Background:

Dietary fat quality is important for health and physical functioning in older adults. Linoleic acid is a dietary polyunsaturated fatty acid that is necessary for optimal inner-mitochondrial membrane function. However, limited evidence exists for examining the role of linoleic acid intake on indices of mobility and physical function. In this pilot study, we sought to examine the associations between linoleic acid intake and physical functioning in older adults.

Methods:

This secondary analysis of data from the Health, Aging, and Body Composition energy expenditure sub-study was conducted for our investigation. Ability to complete physical tasks such as climbing a flight of stairs, walking a quarter mile, and lifting 10 lbs. was self-reported. Daily linoleic acid intake was estimated from a food frequency questionnaire. Persons with daily linoleic acid intake below approximately 85% of Adequate Intake were considered as having low linoleic acid intake. Covariate-adjusted logistic models were used for the analyses.

Results:

The final analytical sample included 317 participants aged 74.4 ± 2.8 years who consumed 18.9 ± 11.4 g/day of linoleic acid, with 78 (24.6%) participants having low daily linoleic acid intake. Persons with low daily linoleic acid intake had 2.58 (95% confidence interval: 1.27–5.24) greater odds for a limitation in climbing stairs.

Conclusions:

Our pilot investigation found that low daily linoleic acid intake could be associated with physical function in older adults. Dietitians working with older patients may want to consider the importance of daily linoleic acid intake for health and certain physical function tasks.

Gender Differences in Body Composition in Pre-Frail Older Adults With Diabetes Mellitus

BACKGROUND & AIMS

Ageing is a risk factor for diabetes mellitus (DM) and frailty. It is associated with body composition changes including increase in fat mass (FM), central fat distribution, decrease in fat free mass (FFM) and skeletal muscle which are risk factors for DM. This study aims to evaluate gender differences in body composition in pre-frail diabetics and association with physical performance, cognitive function and perceived health. In addition, we aim to explore the association of obesity, sarcopenia, sarcopenic obesity, and body composition in pre-frail older adults to DM status.

METHODS

Cross-sectional study of 192 pre-frail community dwelling older adults (≥ 65 years). Data was collected on demographics, physical function, cognition, frailty, sarcopenia, perceived health and body composition using the InBody S10. Univariate and multivariate logistic regression were undertaken to explore the association of sarcopenic obesity, obesity, sarcopenia and body composition measures to DM status.

RESULTS

There were insignificant within-gender differences for physical function, cognition and body composition, except for a higher prevalence of obesity defined by body mass index (BMI) and body fat percentage (BF%), increased fat mass index(FMI) and fat free mass index(FFMI) in females with DM. There were significant between-gender differences for those with DM where females overall had lower education levels, lower perceived health, higher prevalence of depression and low mental vitality, lower overall physical function (low short physical performance battery scores, low gait speed and hand grip strength), lower cognitive scores, lower muscle mass and muscle quality with higher FMI, FM/FFM and visceral fat area(VFA). BMI, VFA>100 cm², FMI and FFMI were found to be independently associated with DM status after multivariable adjustment.

CONCLUSION

Within pre-frail DM vs non-DM, there were insignificant differences in body composition, physical function, cognition and perceived health within gender except for FMI, BF% and FFMI in females. There were significant differences between gender in pre-frail DM in muscle mass, quality, functional, cognitive and mental status. Further longitudinal studies are required to understand the pathogenesis, trajectory of DM and protective role of oral hypoglycemics in pre-frail older adults.

Correlation of Paraspinal Muscle Mass With Decompensation of Sagittal Adult Spinal Deformity After Setting of Fatigue Post 10-Minute Walk

OBJECTIVE

The purpose of this study was to investigate the changes in spinopelvic parameters before and after the setting of muscle fatigue along with its correlation with pre-existing paraspinal and psoas muscle mass.

METHODS

Single-center retrospective review of prospectively collected data was conducted on 145-adults with symptomatic loss of lumbar lordosis (LL). Radiographs were taken before and after walking for 10 minutes. Magnetic resonance imaging was used to calculate paraspinal muscle (PSM) cross-sectional area (CSA), mean signal intensity, fatty infiltration (FI), and lean muscle mass at thoracolumbar junction (T12) and lower lumbar level (L4). Psoas CSA was calculated at L3. Patients were divided into 2 groups namely compensated sagittal deformity (CSD) (SVA ≤ 4 cm, PT > 20°) and decompensated sagittal deformity (DSD) (SVA > 4 cm, PT > 20°) based on prewalk measurements.

RESULTS

Initial mean SVA was 1.8 cm and 11 cm for CSD and DSD respectively (p < 0.01). After walking, significant deteriorations in SVA, PT-LL (p < 0.01) were observed in CSD without significant change in thoracic kyphosis (TK). All sagittal parameters in DSD deteriorated significantly. DSD group had significantly poorer PSM quality at T12 and L4 compared to CSD group. In CSD group, sagittal decompensation correlated with muscle quality, i.e. , decreases in LL (ΔLL) correlated with CSA of PSM/vertebral body (VB) at L4 (r = -0.412, p = 0.046) while increases in TK (ΔTK) correlated with CSA of PSM/VB at T12 (r = 0.477, p = 0.018). ΔSVA and ΔPT correlated with FI at L4 (r = 0.577, p = 0.003 and r = -0.407, p = 0.048, respectively). DSD group, had weak correlations (-0.3 < r < -0.1) between changes in sagittal and PSM parameters.

CONCLUSION

PSM quality in adults with spinal deformity correlates with patients' ability to maintain an upright posture and sagittal decompensation after walking for 10 minutes.

Study of Longitudinal Aging in Mice: Presentation of Experimental Techniques

Aging is associated with functional and metabolic decline and is a risk factor for all noncommunicable diseases. Even though mice are routinely used for modeling human aging and aging-related conditions, no comprehensive assessment to date has been conducted on normative mouse aging. To address this gap, the Study of Longitudinal Aging in Mice (SLAM) was designed and implemented by the National Institute on Aging (NIA/NIH) as the mouse counterpart to the Baltimore Longitudinal Study of Aging (BLSA). In this manuscript, we describe the premise, study design, methodologies, and technologies currently employed in SLAM. We also discuss current and future study directions. In this large population mouse study, inbred C57BL/6J and outbred UM-HET3 mice of both sexes are longitudinally evaluated for functional, phenotypic, and biological health, and collection of biospecimens is conducted throughout their life span. Within the longitudinal cohorts, a cross-sectional arm of the study has also been implemented for the well-controlled collection of tissues to generate a biorepository. SLAM and studies stemming from SLAM seek to identify and characterize phenotypic and biological predictors of mouse aging and age-associated conditions, examine the degrees of functional and biomolecular variability that occur within inbred and genetically heterogeneous mouse populations with age, and assess whether these changes are consistent with alterations observed in human aging in BLSA. The findings from these studies will be critical for evaluating the utility of mouse models for studying different aspects of aging, both in terms of interpreting prior findings and designing and implementing future studies.

The Roles of Body Composition and Specific Strength in the Relationship Between Race and Physical Performance in Older Adults

BACKGROUND

Socioeconomics may explain black-white differences in physical performance; few studies examine racial differences among socioeconomically similar groups. Performance is also affected by body composition and specific strength, which differ by race. We assessed whether racial differences in physical performance exist among older adults with high education and similar income and whether body composition and specific strength attenuate observed differences.

METHODS

Cross-sectional analysis of 536 men (18% black) and 576 women (28% black) aged more than 60 years from the Baltimore Longitudinal Study of Aging. Body composition was evaluated using dual-energy x-ray absorptiometry. Specific strength was assessed by quadricep peak torque divided by height-normalized thigh cross-sectional area and grip strength divided by body mass index-normalized appendicular lean mass. Physical performance was assessed using usual gait speed and fast 400 m walk time. Sex-stratified linear regression models, adjusted for age, height, education, and recent income, determined whether body composition or specific strength attenuated associations between race and physical performance.

RESULTS

Blacks were younger, with higher weight and appendicular lean mass. Black women had higher percent fat and specific strength. In both sexes, blacks had poorer physical performance after adjustment for socioeconomic factors. In women, neither body composition nor specific strength altered the association with gait speed. In men, neither body composition nor specific strength attenuated racial differences in either performance measure.

CONCLUSIONS

Poorer physical performance among black compared to white older adults persists among persons with high education and similar income and cannot generally be attributed to differences in body composition or specific strength.

Skeletal Muscle Health and Cognitive Function: A Narrative Review

Sarcopenia is the loss of skeletal muscle mass and function with advancing age. It involves both complex genetic and modifiable risk factors, such as lack of exercise, malnutrition and reduced neurological drive. Cognitive decline refers to diminished or impaired mental and/or intellectual functioning. Contracting skeletal muscle is a major source of neurotrophic factors, including brain-derived neurotrophic factor, which regulate synapses in the brain. Furthermore, skeletal muscle activity has important immune and redox effects that modify brain function and reduce muscle catabolism. The identification of common risk factors and underlying mechanisms for sarcopenia and cognition may allow the development of targeted interventions that slow or reverse sarcopenia and also certain forms of cognitive decline. However, the links between cognition and skeletal muscle have not been elucidated fully. This review provides a critical appraisal of the literature on the relationship between skeletal muscle health and cognition. The literature suggests that sarcopenia and cognitive decline share pathophysiological pathways. Ageing plays a role in both skeletal muscle deterioration and cognitive decline. Furthermore, lifestyle risk factors, such as physical inactivity, poor diet and smoking, are common to both disorders, so their potential role in the muscle-brain relationship warrants investigation.

Comparison of field- and laboratory-based estimates of muscle quality index between octogenarians and young older adults: an observational study

Muscle quality (the ratio of strength to lean muscle mass) might be a better indicator of muscle function than strength alone. Differences in muscle quality index (MQI) between octogenarians and young older adults remain unclear. The aims of the present cross-sectional study were to compare (1) MQI between octogenarians and young older adults, (2) lab versus field-based MQI tools, and (3) determine possible confounding factors affecting MQI in older adults. Compiled data from two cross-sectional studies included 175 younger and older adults (31 men and 144 women) with a mean age of 75.93±9.49 years. Participants with age ≥80 years old were defined as octogenarians (n=79) and <80 years was defined as young older adults (n=96). Laboratory MQI was derived from the ratio of grip strength to arm muscle mass (in kg) measured by dual-energy x-ray absorptiometry. Field-based MQI was quantified from the ratio of grip strength to body mass index (BMI). Octogenarians displayed lower field (P=0.003) and laboratory MQI (P<0.001) as compared with young older adults. There was a strong correlation effect between field MQI and laboratory MQI (P=0.001, R=0.85). BMI (P=0.001), and diabetes mellitus (P=0.001) negatively affected MQI. Women presented lower MQI (P=0.001) values than men. In light of this information, rehabilitation specialists should consider the use of field-based MQI as a tool for evaluation and follow-up of older population.

A roadmap to build a phenotypic metric of ageing: insights from the Baltimore Longitudinal Study of Aging

Over the past three decades, considerable effort has been dedicated to quantifying the pace of ageing yet identifying the most essential metrics of ageing remains challenging due to lack of comprehensive measurements and heterogeneity of the ageing processes. Most of the previously proposed metrics of ageing have been emerged from cross-sectional associations with chronological age and predictive accuracy of mortality, thus lacking a conceptual model of functional or phenotypic domains. Further, such models may be biased by selective attrition and are unable to address underlying biological constructs contributing to functional markers of age-related decline. Using longitudinal data from the Baltimore Longitudinal Study of Aging (BLSA), we propose a conceptual framework to identify metrics of ageing that may capture the hierarchical and temporal relationships between functional ageing, phenotypic ageing and biological ageing based on four hypothesized domains: body composition, energy regulation, homeostatic mechanisms and neurodegeneration/neuroplasticity. We explored the longitudinal trajectories of key variables within these phenotypes using linear mixed-effects models and more than 10 years of data. Understanding the longitudinal trajectories across these domains in the BLSA provides a reference for researchers, informs future refinement of the phenotypic ageing framework and establishes a solid foundation for future models of biological ageing.

Clinically Meaningful Change for Physical Performance: Perspectives of the ICFSR Task Force

For clinical studies of sarcopenia and frailty, clinically meaningful outcome measures are needed to monitor disease progression, evaluate efficacy of interventions, and plan clinical trials. Physical performance measures including measures of gait speed and other aspects of mobility and strength have been used in many studies, although a definition of clinically meaningful change in performance has remained unclear. The International Conference on Frailty and Sarcopenia Research Task Force (ICFSR-TF), a group of academic and industry scientists investigating frailty and sarcopenia, met in Miami Beach, Florida, USA in February 2019 to explore approaches for establishing clinical meaningfulness in a manner aligned with regulatory authorities. They concluded that clinical meaningful change is contextually dependent, and that both anchor-based and distribution-based methods of quantifying physical function are informative and should be evaluated relative to patient-reported outcomes. In addition, they identified additional research needed to enable setting criteria for clinical meaningful change in trials.

Muscle quality index and isometric strength in older adults with hip osteoarthritis

Background

Older adults with hip osteoarthritis (OA) suffer a progressive loss of muscle quality and strength, affecting their daily activities and quality of life. The purpose of this study is to compare the levels of isometric strength among older adults with and without hip OA and healthy young adults, and to determine the relationship between muscle quality index (MQI) and isometric strength.

Methods

Fourteen subjects with hip OA (65.6 ± 3.0 years), 18 healthy older adults (66.6 ± 6.5 years) and 32 young adults (20.7 ± 2.0 years) participated in the study. MQI, isometric muscle strength of the hip, ten time sit-to-stand tests, and body composition were measured.

Results

The MQI was lower in subjects with hip OA, with no significant differences between groups (p > 0.054). Subjects with OA produced significantly less isometric strength in hip extension (p < 0.001), flexion (p < 0.001), abduction (p < 0.05), adduction (p < 0.001), external (p < 0.05) and internal rotation (p < 0.05). Subjects with OA demonstrated longer time in the execution of the sit-to-stand test (p < 0.001) in comparison with healthy older and young adults. High correlations between MQI, sit-to-stand (r =  - 0.76, p < 0.01) and peak force during hip abduction (r = 0.78, p < 0.01) where found in subjects with OA. Moderate correlation between MQI and peak force during hip flexion (r = 0.55, p < 0.05) and external rotation (r = 0.61, p < 0.05) were found in the OA group.

Conclusions

Subjects with OA have lower MQI than old and young healthy controls. In subjects with OA, there was a significant relationship between isometric strength of hip muscles and performance on the sit-to-stand test and the MQI.

Is muscle mechanical function altered in polycystic ovary syndrome?

PURPOSE

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder of women of reproductive age. The aim of the current study was to assess muscle mechanical function in PCOS and its relationship with hormonal and metabolic features of the syndrome.

METHODS

The study included 44 women with PCOS, all having clinical or biochemical hyperandrogenism, chronic oligo-anovulation and PCOM, and 32 age- and BMI-matched healthy women. Anthropometric, hormonal and biochemical measurements were performed. Muscle mechanical function including lower limb explosive strength and average power (AvP) was measured using isokinetic dynamometry, a valid and reliable instrument for measuring muscle strength.

RESULTS

The mean age and BMI of the women with PCOS and controls were 21.8 ± 3.2 versus 22.8 ± 3 years and 26.1 ± 5.4 versus 25.5 ± 5.7 kg/m², respectively (p = NS for both). PCOS patients had higher androgen levels, whereas total and regional fat and lean body mass and insulin resistance parameters were similar between the groups. The peak muscle force output defined as the peak torque of knee extensor and flexor muscles was higher in normal weight women compared to overweight and obese (p < 0.05 for both) but did not differ in patients and controls. AvP determined by the time-averaged integrated area under the curve at 60°/s angular velocity was higher in the PCOS group for extension and flexion (50.3 ± 21.2 vs 42.1 ± 11.6 and 35.3 ± 27 vs 22.2 ± 11.1, respectively, p < 0.05 for both). These measurements were correlated with bioavailable testosterone (r = 0.29, p = 0.012, r = 0.36, p = 0.001, respectively).

CONCLUSION

Muscle mechanical function is altered in PCOS. Women with PCOS have increased average lower limb power that is associated with hyperandrogenism.

The Comparative Associations of Ultrasound and Computed Tomography Estimates of Muscle Quality with Physical Performance and Metabolic Parameters in Older Men

Estimates of muscle tissue composition may have greater prognostic value than lean body mass levels regarding health-related outcomes. Ultrasound provides a relatively low cost, safe, and accessible mode of imaging to assess muscle morphology. The purpose of this study was to determine the construct validity of muscle echogenicity as a surrogate measure of muscle quality in a sample of older, predominantly African American (AA) participants. We examined the association of rectus femoris echogenicity with mid-thigh computed tomography (CT) scan estimates of intra- and intermuscular adipose tissue (IMAT), basic metabolic parameters via blood sample analysis, muscle strength, and mobility status. This observational study was conducted at a federal medical center and included 30 community-dwelling men (age, 62.5 ± 9.2; AA, n = 24; Caucasian, n = 6). IMAT estimates were significantly associated with echogenicity (r = 0.73, p < 0.001). Echogenicity and IMAT exhibited similar associations with the two-hour postprandial glucose values and high-density lipoproteins values (p < 0.04), as well as grip and isokinetic (180°/s) knee extension strength adjusted for body size (p < 0.03). The significant relationship between ultrasound and CT muscle composition estimates, and their comparative association with key health-related outcomes, suggests that echogenicity should be further considered as a surrogate measure of muscle quality.