Fat Infiltration in the Leg is Associated with Bone Geometry and Physical Function in Healthy Older Women

Gait Speed Reserve in the general population-based 'Good Aging in Skåne' cohort study-distribution and associated factors

Gait Speed Reserve (GSR) expresses a difference between fast and comfortable gait speed and may have an impact on everyday functioning. It was also hypothesized as a useful proxy measure of physiological reserve. However, height-normalizing values of GSR and its associated factors have not been evaluated in a general population of older adults. Therefore, we aimed to investigate the distribution of height-normalized GSR (HN-GSR) in an elderly population-based cohort from urban and rural areas (n = 4342) aged 60-93 years and evaluate associated physiological and lifestyle factors. Using linear mixed models, we identified gender and nine modifiable factors as significantly associated with HN-GSR across four age groups. Better handgrip strength, cognition and standing balance, higher physical activity level, larger calf circumference, and less smoking had positive associations with HN-GSR, while female gender, more leg pain, higher weight and, alcohol consumption had opposite effects. The Marginal R2 imply that this model explained 26% of the variance in HN-GSR. Physical activity and handgrip strength varied across age groups in impact on HN-GSR. The differences were however comparatively minor. In this large cohort study of older adults, we proposed for the first time that factors associated with HN-GSR represented multi-domain features that are in line with previous findings reported for GSR. Measuring HN-GSR/GSR may help clinicians identify early physiological impairments or unhealthy lifestyle habits, especially among older women, and may also have safety implications in daily life. Further work is needed to find out if measuring HN-GSR/GSR may be useful in identifying adverse health outcomes and overall physiological reserve.

Quantification of Extramyocellular Lipids and Intramuscular Fat from Muscle Echo Intensity in Lower Limb Muscles: A Comparison of Four Ultrasound Devices against Magnetic Resonance Spectroscopy

This study aimed to compare different ultrasound devices with magnetic resonance spectroscopy (MRS) to quantify muscle lipid content from echo intensity (EI). Four different ultrasound devices were used to measure muscle EI and subcutaneous fat thickness in four lower-limb muscles. Intramuscular fat (IMF), intramyocellular (IMCL) and extramyocellular lipids (EMCL) were measured using MRS. Linear regression was used to compare raw and subcutaneous fat thickness-corrected EI values to IMCL, EMCL and IMF. IMCL had a poor correlation with muscle EI (r = 0.17-0.32, NS), while EMCL (r = 0.41-0.84, p < 0.05-p < 0.001) and IMF (r = 0.49-0.84, p < 0.01-p < 0.001) had moderate to strong correlation with raw EI. All relationships were improved when considering the effect of subcutaneous fat thickness on muscle EI measurements. The slopes of the relationships were similar across devices, but there were some differences in the y-intercepts when raw EI values were used. These differences disappeared when subcutaneous fat thickness-corrected EI values were considered, allowing for the creation of generic prediction equations (r = 0.41-0.68, p < 0.001). These equations can be used to quantify IMF and EMCL within lower limb muscles from corrected-EI values in non-obese subjects, regardless of the ultrasound device used.

Association Between Pelvic Bone Computed Tomography-Derived Body Composition and Patient Outcomes in Older Adults With Proximal Femur Fracture

OBJECTIVE

To investigate the association between pelvic bone computed tomography (CT)-derived body composition and patient outcomes in older adult patients who underwent surgery for proximal femur fractures.

MATERIALS AND METHODS

We retrospectively identified consecutive patients aged ≥ 65 years who underwent pelvic bone CT and subsequent surgery for proximal femur fractures between July 2018 and September 2021. Eight CT metrics were calculated from the cross-sectional area and attenuation of the subcutaneous fat and muscle, including the thigh subcutaneous fat (TSF) index, TSF attenuation, thigh muscle (TM) index, TM attenuation, gluteus maximus (GM) index, GM attenuation, gluteus medius and minimus (Gmm) index, and Gmm attenuation. The patients were dichotomized using the median value of each metric. Multivariable Cox regression and logistic regression models were used to determine the association between CT metrics with overall survival (OS) and postsurgical intensive care unit (ICU) admission, respectively.

RESULTS

A total of 372 patients (median age, 80.5 years; interquartile range, 76.0-85.0 years; 285 females) were included. TSF attenuation above the median (adjusted hazard ratio [HR], 2.39; 95% confidence interval [CI], 1.41-4.05), GM index below the median (adjusted HR, 2.63; 95% CI, 1.33-5.26), and Gmm index below the median (adjusted HR, 2.33; 95% CI, 1.12-4.55) were independently associated with shorter OS. TSF index (adjusted odds ratio [OR], 6.67; 95% CI, 3.13-14.29), GM index (adjusted OR, 3.45; 95% CI, 1.49-7.69), GM attenuation (adjusted OR, 2.33; 95% CI, 1.02-5.56), Gmm index (adjusted OR, 2.70; 95% CI, 1.22-5.88), and Gmm attenuation (adjusted OR, 2.22; 95% CI, 1.01-5.00) below the median were independently associated with ICU admission.

CONCLUSION

In older adult patients who underwent surgery for proximal femur fracture, low muscle indices of the GM and gluteus medius/minimus obtained from their cross-sectional areas on preoperative pelvic bone CT were significant prognostic markers for predicting high mortality and postsurgical ICU admission.

Exploring the relationships between anthropometric indices of adiposity and physical performance in middle-aged and older Brazilian women: a canonical correlation analysis

OBJECTIVES

This study analyzed the influence of anthropometric indices of adiposity on the physical performance of middle-aged and older women.

METHODS

A cross-sectional study was conducted among 368 women from 50 years to 80 years old. Anthropometric and biochemical characteristics were analyzed, and physical performance was evaluated. The statistical analysis used measures of central tendency and dispersion for descriptive data, Pearson correlations to demonstrate the initial associations between the variables, and canonical correlation (CC) to evaluate the relationship between the set of anthropometric adiposity indices and performance-related variables.

RESULTS

The participants had a mean age of 58.57±8.21 years, a visceral adiposity index of 7.09±4.23, a body mass index of 29.20±4.94 kg/m2, and a conicity index of 1.33±0.07. The average handgrip strength was 25.06±4.89 kgf, gait speed was 1.07±0.23 m/s, and the mean Short Physical Performance Battery (SPPB) score was 10.83±1.36. The first canonical function presented the highest shared variance, CC, and redundancy index (cumulative percentage of variance, 82.52; Wilks' lambda, 0.66; CC, 0.532; p<0.001). From the analysis of this canonical function, the conicity index (-0.59) displayed inverse correlations with handgrip strength (0.84) and the SPPB (0.68), as well as a direct correlation with gait speed (-0.43).

CONCLUSIONS

In middle-aged and older women, there was an inverse relationship between the conicity index and muscle strength and power, while a direct relationship was found between the same index and gait speed.

In vivo Measurement of Intraosseous Vascular Haemodynamic Markers in Human Bone Tissue Utilising Near Infrared Spectroscopy

Objective: Poor vascular health is associated with reduced bone strength and increased risk of fragility fracture. However, direct measurement of intraosseous vascular health is difficult due to the density and mineral content of bone. We investigated the feasibility of using a commercially available continuous wave near infrared spectroscopy (NIRS) system for the investigation of vascular haemodynamics in human bone in vivo.

Approach: An arterial occlusion (AO) protocol was developed for obtaining haemodynamic measurements of the proximal tibia and lateral calf, including assessment of the protocol’s intra operator reproducibility. For 36 participants, intraosseous haemodynamics derived by NIRS were compared to alternative tests of bone health based on dual x-ray absorptiometry (DXA) testing and MRI.

Main Results: Near infrared spectroscopy markers of haemodynamics of the proximal tibia demonstrated acceptable reproducibility, comparable with reproducibility assessments of alternative modalities measuring intraosseous haemodynamics, and the use of NIRS for measuring muscle. Novel associations have been demonstrated between haemodynamic markers of bone measured with NIRS and body composition and bone mineral density (BMD) measurements obtained with both DXA and MRI.

Significance: Near infrared spectroscopy provides inexpensive, non-invasive, safe, and real time data on changes in oxygenated and deoxygenated haemoglobin concentration in bone at the proximal tibia. This study has demonstrated the potential for NIRS to contribute to research investigating the pathophysiological role of vascular dysfunction within bone tissue, but also the limitations and need for further development of NIRS technology.

Uncovering the Bone-Muscle Interaction and Its Implications for the Health and Function of Older Adults (the Wellderly Project): Protocol for a Randomized Controlled Crossover Trial

BACKGROUND

Bone and muscle are closely linked anatomically, biochemically, and metabolically. Acute exercise affects both bone and muscle, implying a crosstalk between the two systems. However, how these two systems communicate is still largely unknown. We will explore the role of undercarboxylated osteocalcin (ucOC) in this crosstalk. ucOC is involved in glucose metabolism and has a potential role in muscle maintenance and metabolism.

OBJECTIVE

The proposed trial will determine if circulating ucOC levels in older adults at baseline and following acute exercise are associated with parameters of muscle function and if the ucOC response to exercise varies between older adults with low muscle quality and those with normal or high muscle quality.

METHODS

A total of 54 men and women aged 60 years or older with no history of diabetes and warfarin and vitamin K use will be recruited. Screening tests will be performed, including those for functional, anthropometric, and clinical presentation. On the basis of muscle quality, a combined equation of lean mass (leg appendicular skeletal muscle mass in kg) and strength (leg press; one-repetition maximum), participants will be stratified into a high or low muscle function group and randomized into the controlled crossover acute intervention. Three visits will be performed approximately 7 days apart, and acute aerobic exercise, acute resistance exercise, and a control session (rest) will be completed in any order. Our primary outcome for this study is the effect of acute exercise on ucOC in older adults with low muscle function and those with high muscle function.

RESULTS

The trial is active and ongoing. Recruitment began in February 2018, and 38 participants have completed the study as of May 26, 2019.

CONCLUSIONS

This study will provide novel insights into bone and muscle crosstalk in older adults, potentially identifying new clinical biomarkers and mechanistic targets for drug treatments for sarcopenia and other related musculoskeletal conditions.

TRIAL REGISTRATION

Australia New Zealand Clinical Trials Registry ACTRN12618001756213; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=375925.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/18777.

Recent Issues on Body Composition Imaging for Sarcopenia Evaluation

Recently, sarcopenia has garnered renewed interest. Sarcopenia is a disease characterized by decreased skeletal muscle mass and strength/function, which can impair the quality of life and increase physical disability, adverse metabolic effects, and mortality. Imaging tools for evaluating and diagnosing sarcopenia have developed rapidly. Radiologists should be aware of sarcopenia and its clinical implications. We review current knowledge about sarcopenia, its pathophysiological impact, and advantages and disadvantages of methods for evaluation of sarcopenia focusing on body composition imaging modalities such as whole-body dual-energy X-ray absorptiometry, CT, and MRI. Controversial issues are discussed, including the lack of consensus and standardization of the disease definition, imaging modality, measurement methods, and diagnostic cutoff points.

Mid-calf skeletal muscle density and its associations with physical activity, bone health and incident 12-month falls in older adults: The Healthy Ageing Initiative

BACKGROUND

Lower skeletal muscle density, indicating greater infiltration of adipose tissue into muscles, is associated with higher fracture risk in older adults. We aimed to determine whether mid-calf muscle density is associated with falls risk and bone health in community-dwelling older adults.

METHODS

2214 community-dwelling men and women who participated in the Healthy Ageing Initiative (Sweden) study at age 70 were included in this analysis. Mid-calf muscle density (mg/cm³) at the proximal tibia, and volumetric bone mineral density (vBMD) and architecture at the distal and proximal tibia and radius, were assessed by peripheral quantitative computed tomography. Whole-body lean and fat mass, lumbar spine and total hip areal bone mineral density (aBMD) were assessed by dual-energy X-ray absorptiometry. Participants completed seven-day accelerometer measurements of physical activity intensity, and self-reported falls data were collected 6 and 12 months later.

RESULTS

302 (13.5%) participants reported a fall at the 6- or 12-month interview, and 29 (1.3%) reported a fall at both interviews. After adjustment for confounders, each standard deviation decrease in mid-calf muscle density was associated with a trend towards greater likelihood of experiencing a fall (OR 1.13; 95% CI 1.00, 1.29 per SD lower) and significantly greater likelihood of multiple falls (1.61; 1.16, 2.23). Higher muscle density was not associated with total hip aBMD, and was associated with lower lumbar spine aBMD (B = -0.003; 95% CI -0.005, -0.001 per mg/cm³) and higher proximal cortical vBMD (0.74; 0.20, 1.28) at the radius. At the tibia, muscle density was positively associated with distal total and trabecular vBMD, and proximal total and cortical vBMD, cortical thickness, cortical area and stress-strain index (all P < 0.05). Only moderate/vigorous (%) intensity physical activity, not sedentary time or light activity, was associated with higher mid-calf muscle density (0.086; 0.034, 0.138).

CONCLUSIONS

Lower mid-calf muscle density is independently associated with higher likelihood for multiple incident falls and appears to have localised negative effects on bone structure in older adults.

Aging and Imaging Assessment of Body Composition: From Fat to Facts

The aging process is characterized by the chronic inflammatory status called "inflammaging", which shares major molecular and cellular features with the metabolism-induced inflammation called "metaflammation." Metaflammation is mainly driven by overnutrition and nutrient excess, but other contributing factors are metabolic modifications related to the specific body composition (BC) changes occurring with age. The aging process is indeed characterized by an increase in body total fat mass and a concomitant decrease in lean mass and bone density, that are independent from general and physiological fluctuations in weight and body mass index (BMI). Body adiposity is also re-distributed with age, resulting in a general increase in trunk fat (mainly abdominal fat) and a reduction in appendicular fat (mainly subcutaneous fat). Moreover, the accumulation of fat infiltration in organs such as liver and muscles also increases in elderly, while subcutaneous fat mass tends to decrease. These specific variations in BC are considered risk factors for the major age-related diseases, such as cardiovascular diseases, type 2 diabetes, sarcopenia and osteoporosis, and can predispose to disabilities. Thus, the maintenance of a balance rate of fat, muscle and bone is crucial to preserve metabolic homeostasis and a health status, positively contributing to a successful aging. For this reason, a detailed assessment of BC in elderly is critical and could be an additional preventive personalized strategy for age-related diseases. Despite BMI and other clinical measures, such as waist circumference measurement, waist-hip ratio, underwater weighing and bioelectrical impedance, are widely used as a surrogate measure for body adiposity, they barely reflect the distribution of body fat. Because of the great advantages offered by imaging tools in research and clinics, the attention of clinicians is now moving to powerful imaging techniques such as computed tomography, magnetic resonance imaging, dual-energy X-ray absorptiometry and ultrasound to obtain a more accurate estimation of BC. The aim of this review is to present the state of the art of the imaging techniques that are currently available to measure BC and that can be applied to the study of BC changes in the elderly, outlining advantages and disadvantages of each technique.

Relationships between fatty infiltration in the thigh and calf in women with knee osteoarthritis

BACKGROUND

In individuals with knee osteoarthritis (OA), fatty infiltration into thigh muscle is associated with poor physical performance and strength. However, it is not known whether this also occurs in the calf and if this impacts physical function.

AIMS

We investigated the relationships between volumes of intramuscular fat (intraMF), intermuscular fat (IMF), subcutaneous fat (SCF), lean muscle and muscle adiposity, in the thighs compared to the calves of women with knee OA.

METHODS

MRI scans of the thigh and calf were acquired from 20 women over 55 years with knee OA (3.0T Discovery MR750, GE Healthcare). Axial IDEAL (iterative decomposition of water and fat with echo asymmetry and least-squares estimation) fat-separated images were segmented to quantify intraMF, IMF, SCF and lean muscle volumes (SliceOmatic 5.0, Tomovision). Correlation and linear regression analyses were run.

RESULTS

We found a positive relationship between thigh and calf intraMF (R ² = 0.592; B = 5.49; p = 0.001), muscle adiposity (R ² = 0.539; B = 0.567; p = 0.001), and SCF volume (R ² = 0.699; B = 12.847; p = 0.001), controlling for waist-to-hip ratio. Relationships between thigh and calf IMF (R ² = 0.239; B = 7.743; p = 0.061), lean muscle (R ² = 0.245; B = 4.149; p = 0.047) and combined intraMF and IMF volume (R ² = 0.242; B = 6.162; p = 0.044) were not significant.

DISCUSSION

Although a correlation exists between thigh and calf muscle adiposity, intraMF and SCF, this does not hold true for IMF or lean muscle. A greater amount of intraMF infiltration occurs in the thigh compared to the calf of women with knee OA.

CONCLUSION

The calf and thigh may both be involved in pathologic changes in muscle composition in knee OA.

Magnetic Resonance Imaging and Spectroscopy to Assess Leg Muscle Macrostructure and Microstructure in Healthy Older Women: A Feasibility Assessment

BACKGROUND

Advanced magnetic resonance (MR) scanning techniques, such as diffusion tensor imaging (DTI) and proton MR spectroscopy (¹H-MRS) permit microstructural evaluation of water diffusivity and intramyocellular lipid content, respectively. We aimed to determine the feasibility of performing advanced MR scanning (proton density [PD] weighted imaging, DTI, and ¹H-MRS) to evaluate properties of leg muscles in older women with respect to: (1) participant recruitment using three community-based strategies; (2) participant tolerance to the MRI scan acquisition protocol; and (3) scan acquisition and analyses protocols.

METHODS

Recruitment feasibility was evaluated based on the number of participants enrolled using various strategies. Participant tolerance was feasible if the scanning session was uninterrupted and image artifacts were absent. Optimal PD imaging, DTI, and ¹H-MRS acquisition and analyses protocols were established.

RESULTS

Nine women (mean age = 71 years) were recruited over four months. The acquisition protocol was well tolerated by all participants. Adaptations were required for women with short stature and vertebral fracture risk. PD-weighted image analyses were improved by using the phased array uniformity enhancement filter to increase tissue contrast.

CONCLUSIONS

It is feasible to use a combination of MR scanning methods to evaluate muscle macrostructure and microstructure in the leg of older women. Our findings suggest that advanced MR scanning methods can be used for future studies interested in quantifying components of muscle structure in older women, but prospective studies are needed to confirm whether change in microstructure can be detected in response to an intervention.

Increased calf and plantar muscle fibrotic contents in obese subjects may cause ankle instability

Obesity is strongly associated with musculoskeletal disorders of the lower limb, including ankle instability and resulting gait problems. In the present study, we aimed to examine, using paired comparisons of subjects, whether moderate duration of obesity in patients with mild to moderate elevations of body mass index (BMI), changes the fibrous contents of muscles that support the ankle mortices, namely calf and plantar muscles. We attempted to examine these parameters because this shall provide direct evidence of whether obesity directly impacts myoarchitecture and support of the adjoining joints. MRI image segmentation and pixel correlations by grey level co-occurrence matrix (GLCM) and entropy were used to analyse the changes. The differences in the means between groups (both GLCM and entropy) were significant from control lean populations (P<0.0001, ANOVA) for the parameters examined for both the calf and the plantar muscles. Reduction in weight should thus be a first-line approach in preventing these changes that may significantly affect quality of life due to gait disturbances.

The Effects of Dietary Omega-3s on Muscle Composition and Quality in Older Adults

This review will focus on findings from the few studies performed to date in humans to examine changes in muscle protein turnover, lean or muscle mass and physical function following fish oil-derived omega-3 fatty acid treatment. Although considerable gaps in our current knowledge exist, hypertrophic responses (e.g., improvements in the rate of muscle protein synthesis and mTOR signaling during increased amino acid availability and an increase in muscle volume) have been reported in older adults following prolonged (8 to 24 weeks) of omega-3 fatty acid supplementation. There is also accumulating evidence that increased omega-3 fatty acid levels in red blood cells are positively related to strength and measures of physical function. As a result, increased omega-3 fatty acid consumption may prove to be a promising low-cost dietary approach to attenuate or prevent aging associated declines in muscle mass and function.

The reliability of a segmentation methodology for assessing intramuscular adipose tissue and other soft-tissue compartments of lower leg MRI images

OBJECTIVE

Determine the reliability of a magnetic resonance (MR) image segmentation protocol for quantifying intramuscular adipose tissue (IntraMAT), subcutaneous adipose tissue, total muscle and intermuscular adipose tissue (InterMAT) of the lower leg.

MATERIALS AND METHODS

Ten axial lower leg MRI slices were obtained from 21 postmenopausal women using a 1 Tesla peripheral MRI system. Images were analyzed using sliceOmatic™ software. The average cross-sectional areas of the tissues were computed for the ten slices. Intra-rater and inter-rater reliability were determined and expressed as the standard error of measurement (SEM) (absolute reliability) and intraclass coefficient (ICC) (relative reliability).

RESULTS

Intra-rater and inter-rater reliability for IntraMAT were 0.991 (95% confidence interval [CI] 0.978-0.996, p < 0.05) and 0.983 (95% CI 0.958-9.993, p < 0.05), respectively. For the other soft tissue compartments, the ICCs were all >0.90 (p < 0.05). The absolute intra-rater and inter-rater reliability (expressed as SEM) for segmenting IntraMAT were 22.19 mm(2) (95% CI 16.97-32.04) and 78.89 mm(2) (95% CI 60.36-113.92), respectively.

CONCLUSION

This is a reliable segmentation protocol for quantifying IntraMAT and other soft-tissue compartments of the lower leg. A standard operating procedure manual is provided to assist users, and SEM values can be used to estimate sample size and determine confidence in repeated measurements in future research.