Effects of Changes in Regional Body Composition on Physical Function in Older Adults: A Pilot Randomized Controlled Trial

Effects of exercise with or without a hypocaloric diet on intermuscular and intramuscular fat: a systematic review

BACKGROUND

Intermuscular (InterMAT) and intramuscular (IntraMAT) adipose tissues are key contributors to skeletal muscle function and metabolic health.

OBJECTIVE

In this systematic review, we aimed to investigate the impact of different types of exercise with or without a hypocaloric diet on reducing InterMAT and IntraMAT in various muscle tissues.

METHOD

A literature search was performed via PubMed, Cochrane Library, Scopus, and Web of Science from inception until February 2025. Eligible RCTs examined the effects of exercise compared to control in adults > 18 years. A narrative synthesis was employed with a registered protocol at CRD42024511531.

RESULTS

Nineteen RCTs were included in the systematic review. Resistance and aerobic exercise alongside a hypocaloric diet displayed inconsistent results in reducing thigh InterMAT. Under non-hypocaloric conditions there were consistently no alterations of InterMAT and IntraMAT irrespective of muscle tissue. When concurrent exercise was followed, no statistically significant changes were observed with or without a hypocaloric diet on thigh InterMAT and IntraMAT. Results were overall lacking in regards to resistance or aerobic exercise and IntraMAT due to the low number of studies.

CONCLUSION

There is potential in reducing thigh InterMAT following resistance or aerobic exercise combined with a hypocaloric diet, although inconsistencies among studies were presented. However, irrespective of exercise type, under non-hypocaloric conditions no benefits were conferred on InterMAT and IntraMAT of any muscle tissue. Further research is warranted to determine the effects of different exercise intensities employing an adequate dietary and hypocaloric control on skeletal muscle InterMAT and particularly IntraMAT.

Exercise and dietary recommendations to preserve musculoskeletal health during weight loss in adults with obesity: A practical guide

Obesity adversely impacts musculoskeletal health, contributing to functional limitations and an increased risk for falls, fractures and disability. Weight loss can mitigate these effects, but strategies that neglect to incorporate evidence-based dietary and/or exercise approaches can exacerbate musculoskeletal and functional declines. Sustainable weight loss requires a personalised approach that prioritises adequate protein intake and essential nutrients to preserve musculoskeletal health. To enhance adherence and long-term success, dietary strategies should be practical, nutritionally balanced and cost-effective. Similarly, exercise programmes should be individually tailored and progressive, with resistance training central to any program prescribed in the context of weight loss, due to its critical role in maintaining muscle and bone mass and strength. When prescribing weight loss strategies involving lifestyle behaviour changes, clinicians must consider their patient's readiness to change. We have used the transtheoretical model of change framework as an example to identify a patient's level of readiness and provided associated motivational interviewing-based strategies to enhance adherence and engagement. This review outlines evidence-based, practical diet and exercise recommendations and behavioural strategies that can facilitate effective and sustainable weight loss, which is particularly important for at-risk populations such as older adults.

The impact of lifestyle-based weight loss in older adults with obesity on muscle and bone health: a balancing act

Despite adverse metabolic and functional consequences of obesity (BMI ≥30 kg/m2), clinical recommendations for weight loss (WL) in older adults (65+ years) with obesity remain controversial. Reluctance stems partly from epidemiologic data demonstrating musculoskeletal tissue loss with WL and increased risk of disability and osteoporotic fracture. Randomized controlled trials in older adults complement and extend knowledge in this area showing: (1) lifestyle-based WL interventions often yield clinically meaningful (~8%-10%) WL in older adults; (2) lean mass loss is significant, although fat mass loss is preferential and physical performance is often improved, particularly when combined with aerobic and resistance training (RT); (3) bone loss is also significant, with some evidence that RT can attenuate WL-associated bone loss; and (4) fat mass regain after intervention cessation is common, yet physical performance gains appear to be maintained. Best practices for treating older adults with obesity include comprehensive assessment of baseline musculoskeletal health; patient-centered goal setting; moderate (i.e., -500 kcal/day) caloric restriction ensuring protein (1-1.2 g/kg/day), calcium (1000-1200 mg/day), and vitamin D (800-1000 IU/day) needs are met; incorporation of RT (≥2 days/week) and moderate-intensity weight-bearing aerobic training (≥150 min/week); and delivery of care by a multidisciplinary team.

Incidence of a Multicomponent Physical Exercise Program on Body Composition in Overweight or Obese People Aged 60 Years or Older from Chile

This research aimed to explore the changes produced in body mass index (BMI), fat mass percentage (FMP), muscle mass percentage (MMP), and visceral fat percentage (VFP) in 60-year-old or over overweight or obese people after a multicomponent exercise program. This quasi-experimental study involved 70 overweight or obese older people between 60 and 86 years old (M = 73.15; SD = 5.94) who were randomly assigned to a control group (CG, n = 35) and an experimental group (EG, n = 35). At the beginning and at the end of the intervention program, anthropometric and body composition data were collected. The results showed an increase in BMI after the intervention in the CG (p = 0.010) and a decrease in the EG (p < 0.001). The results regarding the FMP indicate a significant decrease in the EG (p < 0.001) after the intervention, as occurs with the VFP (p = 0.003). The MMP increased in the EG (p < 0.001) after the intervention program. Regarding gender, statistically significant differences were found in the MMP after the intervention (p = 0.025), with higher percentages in men in the EG. VFP decreased in both men (p = 0.005) and women (p = 0.019) in the EG. From the results obtained, we can say that a 6-month multicomponent program produces a decrease in BMI, FMP, and VFP and an increase in MMP in its participants. This type of intervention seems to produce a greater increase in muscle mass in men than in women and a decrease in VFP in both genders.

Time-Efficient, High-Resistance Inspiratory Muscle Strength Training Increases Exercise Tolerance in Midlife and Older Adults

PURPOSE

This study aimed to determine if time-efficient, high-resistance inspiratory muscle strength training (IMST), comprising 30 inhalation-resisted breaths per day, improves cardiorespiratory fitness, exercise tolerance, physical function, and/or regional body composition in healthy midlife and older adults.

METHODS

We performed a double-blind, randomized, sham-controlled clinical trial (NCT03266510) testing 6 wk of IMST (30 breaths per day, 6 d·wk -1 , 55%-75% maximal inspiratory pressure) versus low-resistance sham training (15% maximal inspiratory pressure) in healthy men and women 50-79 yr old. Subjects performed a graded treadmill exercise test to exhaustion, physical performance battery (e.g., handgrip strength, leg press), and body composition testing (dual x-ray absorptiometry) at baseline and after 6 wk of training.

RESULTS

Thirty-five participants (17 women, 18 men) completed high-resistance IMST ( n = 17) or sham training ( n = 18). Cardiorespiratory fitness (V̇O 2peak ) was unchanged, but exercise tolerance, measured as treadmill exercise time during a graded exercise treadmill test, increased with IMST (baseline, 539 ± 42 s; end intervention, 606 ± 42 s; P = 0.01) but not sham training (baseline, 562 ± 39 s; end intervention, 553 ± 38 s; P = 0.69). IMST increased peak RER (baseline, 1.09 ± 0.02; end intervention, 1.13 ± 0.02; P = 0.012), peak ventilatory efficiency (baseline, 25.2 ± 0.8; end intervention, 24.6 ± 0.8; P = 0.036), and improved submaximal exercise economy (baseline, 23.5 ± 1.1 mL·kg -1 ⋅min -1 ; end intervention, 22.1 ± 1.1 mL·kg -1 ⋅min -1 ; P < 0.001); none of these factors were altered by sham training (all P > 0.05). Changes in plasma acylcarnitines (targeted metabolomics analysis) were consistently positively correlated with changes in exercise tolerance after IMST but not sham training. IMST was associated with regional increases in thorax lean mass (+4.4%, P = 0.06) and reductions in trunk fat mass (-4.8%, P = 0.04); however, peripheral muscle strength, muscle power, dexterity, and mobility were unchanged.

CONCLUSIONS

These data suggest that high-resistance IMST is an effective, time-efficient lifestyle intervention for improving exercise tolerance in healthy midlife and older adults.

The usefulness of Integrative Neuromuscular Training to counteract obesity: a narrative review

BACKGROUND AND OBJECTIVE

The association between physical activity and diet has a valuable impact in weight status management to counteract obesity. In this context, within different training strategies (i.e., endurance, resistance training, concurrent training, agility training) the Integrative Neuromuscular Training (INT) represents a structured training mode focused on global human movement pattern development with the aim to enhance motor control, mobility and stability. In this narrative review we aimed to discuss the feasibility of INT interventions on physical fitness and body composition outcomes in individuals with obesity.

SUBJECTS

Medline/PubMed, EMBASE, Web of Science, Google Scholar including were searched before 1st February 2023 without restrictions on publication year.

METHODS

Two researchers extracted data from published trials. Randomized controlled trials or clinical trials, Body Mass Index of children and adolescents at the 95% percentile or greater, and for adults to be above 30 kg/m2, detailed intervention description, randomization process and allocation into an experimental or a control group, trials must have been written in English, were included.

RESULTS

We included a total of 19 studies complying with the inclusion criteria for the review process. There is evidence that INT promotes positive adaptations in fitness levels in both younger and older participants with concomitant ameliorations during a shorter, medium and longer time period. Moreover, cardiorespiratory fitness, muscular strength, balance, postural control and body composition reached significant remarkable improvements following a specific intervention based on INT principles compared to other training mode. However, Body Mass Index, fat mass percentage and waist circumference showed similar changes overtime.

CONCLUSIONS

Taken together, these findings support the effectiveness of INT in ameliorating physical fitness (i.e., health-related and skill related components) without negative changes in body composition. Nevertheless, fitness coaches and therapists may consider this training modality a feasible option when prescribing physical exercise in outpatients with obesity.

Mitochondrial Energetics in Skeletal Muscle Are Associated With Leg Power and Cardiorespiratory Fitness in the Study of Muscle, Mobility and Aging

BACKGROUND

Mitochondrial energetics are an important property of aging muscle, as generation of energy is pivotal to the execution of muscle contraction. However, its association with functional outcomes, including leg power and cardiorespiratory fitness, is largely understudied.

METHODS

In the Study of Muscle, Mobility, and Aging, we collected vastus lateralis biopsies from older adults (n = 879, 70-94 years, 59.2% women). Maximal State 3 respiration (Max OXPHOS) was assessed in permeabilized fiber bundles by high-resolution respirometry. Capacity for maximal adenosine triphosphate production (ATPmax) was measured in vivo by 31P magnetic resonance spectroscopy. Leg extension power was measured with a Keiser press system, and VO2 peak was determined using a standardized cardiopulmonary exercise test. Gender-stratified multivariate linear regression models were adjusted for age, race, technician/site, adiposity, and physical activity with beta coefficients expressed per 1-SD increment in the independent variable.

RESULTS

Max OXPHOS was associated with leg power for both women (β = 0.12 Watts/kg, p < .001) and men (β = 0.11 Watts/kg, p < .050). ATPmax was associated with leg power for men (β = 0.09 Watts/kg, p < .05) but was not significant for women (β = 0.03 Watts/kg, p = .11). Max OXPHOS and ATPmax were associated with VO2 peak in women and men (Max OXPHOS, β women = 1.03 mL/kg/min, β men = 1.32 mL/kg/min; ATPmax β women = 0.87 mL/kg/min, β men = 1.50 mL/kg/min; all p < .001).

CONCLUSIONS

Higher muscle mitochondrial energetics measures were associated with both better cardiorespiratory fitness and greater leg power in older adults. Muscle mitochondrial energetics explained a greater degree of variance in VO2 peak compared to leg power.

Thigh and Calf Myosteatosis are Strongly Associated with Muscle and Physical Function in African Caribbean Men

BACKGROUND

African Caribbeans have higher levels of myosteatosis than other populations; however, little is known about the impact of myosteatosis on physical function in African Caribbeans. Herein, we examined the association between regional myosteatosis of the calf, thigh, and abdomen versus physical function in 850 African-Ancestry men aged 64.2 ± 8.9 (range 50-95) living on the Caribbean Island of Tobago.

METHODS

Myosteatosis was measured using computed tomography and included intermuscular adipose tissue (IMAT) and muscle density levels of the thigh, calf, psoas, and paraspinous muscles. Outcomes included grip strength, time to complete 5 chair-rises, and 4-meter gait speed. Associations were quantified using separate linear models for each myosteatosis depot and were adjusted for age, height, demographics, physical activity, and chronic diseases. Beta coefficients were presented per standard deviation of each myosteatosis depot.

RESULTS

Higher thigh IMAT was the only IMAT depot significantly associated with weaker grip strength (β = -1.3 ± 0.43 kg, p = .003). However, lower muscle density of all 4 muscle groups was associated with weaker grip strength (all p < .05). Calf and thigh myosteatosis (IMAT and muscle density) were significantly associated with both worse chair rise time and gait speed (all p < .05), whereas psoas IMAT and paraspinous muscle density were associated with gait speed.

CONCLUSION

Myosteatosis of the calf and thigh-but not the abdomen-were strongly associated with grip strength and performance measures of physical function in African Caribbean men. However, posterior abdominal myosteatosis may have some utility when abdominal images are all that are available.

Intermuscular adipose tissue in metabolic disease

Intermuscular adipose tissue (IMAT) is a distinct adipose depot described in early reports as a 'fatty replacement' or 'muscle fat infiltration' that was linked to ageing and neuromuscular disease. Later studies quantifying IMAT with modern in vivo imaging methods (computed tomography and magnetic resonance imaging) revealed that IMAT is proportionately higher in men and women with type 2 diabetes mellitus and the metabolic syndrome than in people without these conditions and is associated with insulin resistance and poor physical function with ageing. In parallel, agricultural research has provided extensive insight into the role of IMAT and other muscle lipids in muscle (that is, meat) quality. In addition, studies using rodent models have shown that IMAT is a bona fide white adipose tissue depot capable of robust triglyceride storage and turnover. Insight into the importance of IMAT in human biology has been limited by the dearth of studies on its biological properties, that is, the quality of IMAT. However, in the past few years, investigations have begun to determine that IMAT has molecular and metabolic features that distinguish it from other adipose tissue depots. These studies will be critical to further decipher the role of IMAT in health and disease and to better understand its potential as a therapeutic target.

The relationship of alpha-synuclein to mitochondrial dynamics and quality control

Maintenance of mitochondrial health is essential for neuronal survival and relies upon dynamic changes in the mitochondrial network and effective mitochondrial quality control mechanisms including the mitochondrial-derived vesicle pathway and mitophagy. Mitochondrial dysfunction has been implicated in driving the pathology of several neurodegenerative diseases, including Parkinson’s disease (PD) where dopaminergic neurons in the substantia nigra are selectively degenerated. In addition, many genes with PD-associated mutations have defined functions in organelle quality control, indicating that dysregulation in mitochondrial quality control may represent a key element of pathology. The most well-characterized aspect of PD pathology relates to alpha-synuclein; an aggregation-prone protein that forms intracellular Lewy-body inclusions. Details of how alpha-synuclein exerts its toxicity in PD is not completely known, however, dysfunctional mitochondria have been observed in both PD patients and models of alpha-synuclein pathology. Accordingly, an association between alpha-synuclein and mitochondrial function has been established. This relates to alpha-synuclein’s role in mitochondrial transport, dynamics, and quality control. Despite these relationships, there is limited research defining the direct mechanisms linking alpha-synuclein to mitochondrial dynamics and quality control. In this review, we will discuss the current literature addressing this association and provide insight into the proposed mechanisms promoting these functional relationships. We will also consider some of the alternative mechanisms linking alpha-synuclein with mitochondrial dynamics and speculate what the relationship between alpha-synuclein and mitochondria might mean both physiologically and in relation to PD.

Clinical Features and Body Composition in Men with Hormone-Sensitive Metastatic Prostate Cancer: A Pilot Study Examining Differences by Race

Black men treated with frontline therapies for metastatic prostate cancer (MPC) show better clinical outcomes than non-Black men receiving similar treatments. Variations in body composition may contribute to these findings. However, preliminary data are required to support this concept. We conducted a retrospective cohort study for all men with MPC evaluated at our center over a 4-year period, collecting demographic and clinical data (N = 74). Of these, 55 men had diagnostic computed tomography images to quantify adipose tissue and skeletal muscle, specifically sarcopenia and myosteatosis. Nineteen men had repeat imaging to explore changes over time. Frequencies, medians, interquartile ranges, and time to event analyses (hazard ratios (HR); confidence interval (CI)) are presented, stratified by race. Overall, 49% (n = 27) of men had sarcopenia, 49% (n = 27) had myosteatosis, and 29% (n = 16) had sarcopenia and myosteatosis simultaneously. No significant relationship between body mass index (Log-rank $p=0.86$ ; HR: 1.05, 95% CI: 0.45–2.49) or sarcopenia (Log-rank $p=0.92$ ; HR: 1.01, 95% CI: 0.46–2.19) and overall survival was observed. However, the presence of myosteatosis at diagnosis was associated with decreased overall survival (Log-rank $p=0.09$ ; HR: 2.34, 95% CI: 1.05–5.23), with more pronounced (statistically nonsignificant) negative associations for Black (HR: 4.39, 95% CI: 0.92–21.1, $p=0.06$ ) versus non-Black men (HR: 1.89, 95% CI: 0.79–4.54, $p=0.16$ ). Over the median 12.5 months between imaging, the median decline in skeletal muscle was 4% for all men. Black men displayed a greater propensity to gain more adipose tissue than non-Black men, specifically subcutaneous ( $p=0.01$ ). Because of the potential for Type II errors in this pilot, future studies should seek to further evaluate the implications of body composition on outcomes. This will require larger, adequately powered investigations with diverse patient representation.

Long Term Weight Loss Diets and Obesity Indices: Results of a Network Meta-Analysis

Background

Scientists have been investigating efficient interventions to prevent and manage obesity. This network meta-analysis (NMA) compared the effect of different diets [moderate macronutrients (MMs), low fat/high carbohydrate (LFHC), high fat/low carbohydrate (HFLC), and usual diet (UD)] on weight, body mass index (BMI), and waist circumference (WC) changes at ≥12 months.

Methods

We searched Medline, Embase, PubMed databases, and the Cochrane Library. We systematically assessed randomized controlled trials (RCTs) evaluating dietary interventions on adults (mean BMI ≥ 25 kg/m²) receiving active dietary counseling for ≥12 months. We pooled the data using a random-effect NMA. We assessed the quality of the included RCTs using the Cochrane risk of bias (ROB) tool.

Results

We included 36 trials, 14 of which compared HFLC with MM diets. Compared with UD, all diets were associated with a significant weight loss (WL) at ≥12 months, HFLC [mean difference in kg (95% CI): −5.5 (−7.6; −3.4)], LFHC [−5.0 (−7.1; −2.9)] and MM [−4.7 (−6.8; −2.7)]. HFLC, compared with MM diet, was associated with a slightly higher WL (of −0.77 kg) and drop in BMI (of −0.36 kg/m²), while no significant difference was detected in other dietary comparisons. WC was lower with all diets compared to UD, with no significant difference across specific diets. There was no significant interaction of the results with the pre-specified sub-groups. The ROB was moderate to high, mostly related to unclear allocation concealment, high dropout rate and unclear or lack of blinding of participants, providers, and outcome assessors.

Conclusion

Dietary interventions extending over ≥12 months are superior to UD in inducing weight, BMI and WC loss. HFLC might be associated with a slightly higher WL compared with MM diets.

Systematic Trial Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=103116, PROSPERO (CRD42018103116).

Myosteatosis at diagnosis is adversely associated with 2-year survival in women with estrogen receptor-negative metastatic breast cancer

PURPOSE

To examine the relationship between skeletal muscle (SM) and cancer-specific outcomes for women with estrogen receptor-negative (ER-) metastatic breast cancer (MBC).

METHODS

For this retrospective cohort, females (≥ 18 years) with histologically confirmed ER- MBC and computerized tomography (CT) imaging were screened. Demographic, anthropometric, and clinical data were collected uniformly from the electronic medical record. CT images inclusive of the third lumbar region (L3) at diagnosis, 6 and 12 months, were used to classify sarcopenia (≤ 41 cm²/m²) and myosteatosis (< 41 or 33 Hounsfield Units, adjusted for body mass index (BMI)) and to evaluate changes in SM and total adipose tissue (TAT) over time. Kaplan-Meier curves, Cox Proportional Hazards (PH), and restricted mean survival time (RMST) estimates were generated to examine the relationship between sarcopenia and myosteatosis and time to tumor progression (TTP), treatment toxicity and 2-year survival, adjusting for covariates.

RESULTS

Participants were 58.0 (15.0) years of age, ethnically diverse (55% non-Hispanic white, 31% Black, 11% Hispanic), post-menopausal (73%, n = 111), and classified as overweight (BMI 29.4 (7.6)). At diagnosis, 40% (n = 61) were sarcopenic, 49% had myosteatosis, and 28% (n = 42) had both. While Cox PH modeling and RMST analysis reveal no significant relationship between sarcopenia at diagnosis and 2-year survival (RMST difference - 1.6 (1.4) months, HR 1.35 (0.88-2.08)), these analyses support a significant, adverse association between myosteatosis at diagnosis and 2-year survival (RMST difference - 2.4 (1.5) months, HR 1.72 (1.09-2.72)). Incident sarcopenia was 11% (n = 5/45) and 2.5% (n = 1/40), respectively, while incident myosteatosis was 19% (n = 8/42) and 15% (n = 5/34) at 6 and 12 months, respectively. TTP and treatment toxicities did not appear to be related to diagnostic SM or body composition changes over time.

CONCLUSION

Targeted interventions initiated within the first year of diagnosis to preserve or improve SM quality seem warranted for women with ER-MBC.

Effect of Aerobic or Resistance Exercise, or Both, on Intermuscular and Visceral Fat and Physical and Metabolic Function in Older Adults with Obesity While Dieting

BACKGROUND

Obesity exacerbates age-related effects on body composition, physical and metabolic function. Which exercise mode is most effective in mitigating these deleterious changes in dieting obese older adults is unknown.

METHODS

In a randomized controlled trial, we performed a head-to-head comparison of aerobic (AEX), resistance (REX), or combination (COMB) exercise during matched weight loss in 160 obese older adults. Prespecified analyses compared 6-month changes in intermuscular adipose tissue (IMAT) and visceral adipose tissue (VAT) assessed using MRI, insulin sensitivity index (ISI) by oral glucose tolerance test, physical function using Modified Physical Performance Test (PPT), VO2peak, gait-speed, and knee strength by dynamometry.

RESULTS

IMAT and VAT decreased more in COMB than AEX and REX groups (IMAT; -41% vs. -28% and -23% and VAT: -36% vs. -19% and -21%; p=.003 to .01); IMAT and VAT decreased in all groups more than control (CON) (between-group p<.001). ISI increased more in COMB than AEX and REX groups (86% vs. 50% and 39%; p=.005 to .03). PPT improved more in COMB than AEX and REX groups, while VO2peak improved more in COMB and AEX than REX group (all p<.05). Knee strength improved more in COMB and REX than AEX group (all p<.05). Changes in IMAT and VAT correlated with PPT (r=-.28 and -.39), VO2peak (r=-.49 and -.52), gait-speed (r=-.25 and -.36), and ISI (r=-.49 and -.52) (all p<.05).

CONCLUSIONS

Weight loss plus combination aerobic and resistance exercise was most effective in improving ectopic fat deposition and physical and metabolic function in older adults with obesity.

Association of Low Muscle Density With Deteriorations in Muscle Strength and Physical Functioning in Rheumatoid Arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is associated with low muscle density due to the accumulation of intramuscular fat. The present study was undertaken to identify predictors of changes in muscle density and to determine whether low muscle density predicted changes in strength and physical function.

METHODS

Patients with RA, ages 18-70 years, completed whole-body dual-energy x-ray absorptiometry and peripheral quantitative computed tomography to quantify lean and fat mass indices and muscle density. Dynamometry was used to measure strength at the hand, knee, and lower leg. Disability and physical function were measured with the Health Assessment Questionnaire (HAQ) and the Short Physical Performance Battery (SPPB). Assessments were performed at baseline and at follow-up. Regression analyses assessed associations between patient characteristics, muscle density, and deteriorations in strength and function.

RESULTS

Muscle density was assessed at baseline in 107 patients with RA. Seventy-nine of these patients (74%) returned for a follow-up assessment at a median follow-up time of 2.71 years (interquartile range 2.35-3.57). Factors associated with declines in muscle density included female sex, higher disease activity, smoking, and lower insulin-like growth factor 1 (IGF-1) levels. Greater muscle density Z score at baseline (per 1 SD) was associated with less worsening per year according to HAQ, SPPB, and 4-meter walk time scores and a lower risk of a clinically important worsening in HAQ score (odds ratio [OR] 1.90 [95% confidence interval (95% CI) 1.06, 3.42]; P = 0.03) and walking speed (OR 2.87 [95% CI 1.05, 7.89]; P = 0.04).

CONCLUSION

Worsening of skeletal muscle density occurred in patients with higher disease activity, in smokers, and in those with lower IGF-1. Low muscle density was associated with worsening of physical function. Interventions addressing reductions in muscle quality might prevent functional decline.

Validation of a description of sarcopenic obesity defined as excess adiposity and low lean mass relative to adiposity

BACKGROUND

This study aims to assess the construct validity of a body composition-defined definition of sarcopenic obesity based on low appendicular lean mass relative to fat mass (ALMIFMI ) and high fat mass index (FMI) and to compare with an alternative definition using appendicular lean mass index (ALMI) and percent body fat (%BF).

METHODS

This is a secondary analysis of two cohort studies: the National Health and Examination Survey (NHANES) and the Health, Aging, and Body Composition study (Health ABC). Sarcopenic obesity was defined as low ALMIFMI combined with high FMI and was compared with a widely used definition based on ALMI and %BF cut-points. Body composition Z-scores, self-reported disability, physical functioning, and incident disability were compared across body composition categories using linear and logistic regression and Cox proportional hazards models.

RESULTS

Among 14, 850 participants from NHANES, patients with sarcopenic obesity defined by low ALMIFMI and high FMI (ALMIFMI -FMI) had above-average FMI Z-scores [mean (standard deviation): 1.00 (0.72)]. In contrast, those with sarcopenic obesity based on low ALMI and high %BF (ALMI-%BF) had below-average FMI Z-scores. A similar pattern was observed for 2846 participants from Health ABC. Participants with sarcopenic obesity based on ALMIFMI -FMI had a greater number of disabilities, worse physical function, and a greater risk of incident disability compared with those defined based on ALMI-%BF.

CONCLUSIONS

Body composition-defined measures of sarcopenic obesity defined as excess adiposity and lower-than-expected ALMI relative to FMI are associated with functional deficits and incident disability and overcome the limitations of using %BF in estimating obesity in this context.

Effect of exercise on myosteatosis in adults: a systematic review and meta-analysis

Muscle tissue typically contains only small amounts of adipose tissue, and the excess deposition of adiposity is considered a pathological phenomenon termed myosteatosis. Several studies have assessed the effects of exercise alone on the severity of myosteatosis, and some studies have reported promising results. We performed a systematic review and meta-analysis to investigate the effects of exercise interventions on myosteatosis (i.e., lipid infiltration and muscle radiation attenuation). Studies were identified through a systematic search of three databases and limited to randomized controlled trials (RCTs) focused on evaluating the effect of exercise interventions on lipid infiltration and/or muscle attenuation in adults. Thirteen studies met the inclusion criteria, and 12 were included in the meta-analysis (n = 465, 84.7% women). The volume of lipid infiltration was decreased in the exercise group compared with the control group [Hedges' g = -0.45, 95% confidence interval (CI), -0.74 to -0.16; P = 0.008, I² = 0%], and the degree of muscle radiation attenuation was increased (Hedges' g = 0.67, 95% CI, 0.22 to 1.13; P = 0.009, I² = 59.3%). Based on meta-regression analyses, there were no significant effects of mean age at baseline (lipid infiltration, β = -0.008, 95% CI, -0.035 to 0.019; P = 0.495; muscle radiation attenuation, β = -0.013, 95% CI, -0.036 to 0.011; P = 0.248) and intervention duration (lipid infiltration, β = -0.008, 95% CI, -0.028 to 0.010; P = 0.311; muscle radiation attenuation, β = -0.018, 95% CI, -0.050 to 0.014; P = 0.230) on the effect size estimates. Overall, our findings indicate that exercise can significantly improve muscle quality in populations at risk of developing obesity and sarcopenia-related disability.NEW & NOTEWORTHY Muscle tissue typically contains only small amounts of adipose tissue, and the excess deposition of adiposity is considered a pathological phenomenon termed myosteatosis. The volume of lipid infiltration tissue was decreased in the exercise group compared with the control group, and muscle attenuation coefficient was increased. Based on the meta-regression analyses, the mean age at baseline and intervention duration did not affect the effect size estimates for lipid infiltration tissue and muscle radiation attenuation.

Effects of a lifestyle intervention on body composition in prostate cancer patients on androgen deprivation therapy

Background

Exercise and dietary (EX+D) interventions could represent an optimal treatment for attenuating or reversing adverse effects of androgen deprivation therapy (ADT) in prostate cancer (PCa) patients. The Individualized Diet and Exercise Adherence-Pilot (IDEA-P) trial compared the effects of an EX+D intervention relative to standard-of-care (SC) treatment among PCa patients undergoing ADT. The present study evaluated the effects of the EX+D intervention on body composition (BC) obtained via dual-energy X-ray absorptiometry (DXA) in a subsample of IDEA-P patients. A secondary objective was to explore the association of adiposity and lean mass with mobility performance and strength.

Methods

Complete DXA data were acquired from a subsample of 22 PCa patients (EX+D: n = 13; SC: n = 9) at baseline and 3 month follow-up. Intention-to-treat analysis included data from 30 participants (M age = 66.28; SD = 7.79) with baseline DXA assessments.

Results

Intention-to-treat analysis revealed EX+D resulted in significant improvements in fat mass (P = 0.022), per cent fat mass (P = 0.028), trunk fat mass (P = 0.017), fat mass/lean mass (P = 0.040), and per cent lean mass (P = 0.026) vs. SC. EX+D also resulted in more favourable changes in appendicular lean mass/body mass (d = 0.59). Select BC outcomes were also significantly correlated with mobility performance and strength (P < 0.05) at 3 month follow-up.

Conclusions

Findings suggest the EX+D intervention resulted in superior preservation of lean tissue and improvement in adiposity relative to SC treatment. Results underscore the utility of implementing EX+D interventions for preserving muscle mass and reducing adiposity in PCa patients undergoing ADT.

Anti-Inflammatory Strategies Targeting Metaflammation in Type 2 Diabetes

One of the concepts explaining the coincidence of obesity and type 2 diabetes (T2D) is the metaflammation theory. This chronic, low-grade inflammatory state originating from metabolic cells in response to excess nutrients, contributes to the development of T2D by increasing insulin resistance in peripheral tissues (mainly in the liver, muscles, and adipose tissue) and by targeting pancreatic islets and in this way impairing insulin secretion. Given the role of this not related to infection inflammation in the development of both: insulin resistance and insulitis, anti-inflammatory strategies could be helpful not only to control T2D symptoms but also to treat its causes. This review presents current concepts regarding the role of metaflammation in the development of T2D in obese individuals as well as data concerning possible application of different anti-inflammatory strategies (including lifestyle interventions, the extra-glycemic potential of classical antidiabetic compounds, nonsteroidal anti-inflammatory drugs, immunomodulatory therapies, and bariatric surgery) in the management of T2D.

Higher and Lower Muscle Echo Intensity in Elderly Individuals Is Distinguished by Muscle Size, Physical Performance and Daily Physical Activity

This study was performed to identify factors that discriminate muscle echo intensity (EI) among parameters of body composition, physical function and daily physical activity in elderly individuals. A total of 209 men and women (73.7 ± 2.8 y) were evaluated. EI was measured on ultrasonographic axial thigh muscle images. The participants were categorized into the low, mid and high EI groups. We measured the skeletal muscle mass index (SMI) and physical functions. The high EI group exhibited a significantly lower SMI, slower 5-m walking time and shorter 6-min walking distance than the low EI group and had a shorter moderate-intensity activity time than the mid EI group. As a result of the discriminant analysis, elderly individuals were categorized into EI groups by SMI, daily activity and physical function. The data indicate that morphologic and functional parameters and the daily activity level help to discriminate higher and lower muscle EI.

Factors Affecting Activity Limitation in the Elderly: Data Processed from the Korea National Health and Nutrition Examination Survey, 2016

Objectives

The aim of this study was to compare the sociodemographic characteristics, depression, and the health-related quality of life outcome, among the Korean elderly population, with and without activity limitation.

Methods

The data used was drawn from the raw data of the seventh Korea National Health and Nutrition Examination Survey (N = 8,150). There were 1,632 records for individuals aged 65 or older extracted from the seventh Korea National Health and Nutrition Examination Survey database, 199 of those had missing responses (n = 1,433). Differences within the sociodemographic characteristic, the Patient Health Questionnaire-9, and the EuroQol-5 Dimension were analyzed using logistic regression analysis according to the presence or absence of activity limitation.

Results

The prevalence of activity limitation among the elderly individuals surveyed was 19.9%. In the unadjusted regression analysis, the odds ratios of all independent variables (age, gender, education level, type of region, family income, the Patient Health Questionnaire-9, all 5 domains of the EuroQol-5 Dimension) between the elderly individuals with and without activity limitation, were significant. Although, in the adjusted logistic regression analysis, it was observed that the only factors that were significantly associated with activity limitation were the Patient Health Questionnaire-9, EuroQol-5 Dimension, type of region, and family income.

Conclusion

These findings demonstrated that activity limitation in elderly individuals is associated with the sociodemographic characteristics of family income and type of region of residence, as well as depression and the health-related quality of life outcome.

Practice of physical activity and dysmobility syndrome in community-dwelling older adults

The aim this study was to analyze the association between insufficient physical activity and dysmobility syndrome (DS) in community-dwelling older adults. In total, 375 subjects were evaluated aged ≥60 years. For the diagnosis of DS the presence of ≥3 clinical factors was considered: (a) low muscle mass; (b) low muscular strength; (c) low gait speed; (d) high body fat, and (e) osteoporosis. Information relating to the practice of habitual physical activity (HPA) was obtained using a questionnaire and accelerometry. The chi-square test was used to verify the association between HPA and DS and analysis of binary logistic regression to build multiple models. Insufficiently active older adults are approximately 2 times (95% confidence interval, 1.14-3.79) more likely to have DS, independent of body mass index, smoking and ethnicity. The insufficient practice of physical activity is associated with DS in older adults, mainly in women and older.

Treatment of obesity in older persons-A systematic review

The study aims to systematically review the available evidence regarding weight loss interventions (lifestyle, surgical, and pharmacological) for obesity in adults aged over 60 years. A search of prospective, randomized studies took place in January 2018, on Medline (Web of Science) and PubMed databases. Search terms included the following: elderly, obese, hypocaloric, pharmacotherapy, and bariatric surgery. Abstracts were screened for eligibility. A total of 256 publications regarding lifestyle interventions were identified; of these, 69 studies were eligible. As no eligible studies were identified for pharmacotherapy or bariatric surgery, the search was broadened to include non- randomized studies. Four pharmacotherapy and 66 surgery studies were included. Lifestyle intervention had similar weight loss efficacy in older compared with younger people, with positive effects on a number of relevant outcomes, including physical function and cardiovascular parameters. There was little data regarding obesity pharmacotherapy in older persons. The available data for bariatric surgery indicate comparable weight loss and resolution of type 2 diabetes, with similar or slightly higher complication rates in older compared with younger people. Older age alone should not be considered a contraindication to intensive lifestyle or surgical intervention for obesity. There are insufficient data to guide clinical decisions regarding obesity pharmacotherapy in older people.

Intermuscular Adipose Tissue: A Brief Review of Etiology, Association With Physical Function and Weight Loss in Older Adults

Adipose tissue redistributes during aging resulting in increased intermuscular adipose tissue (IMAT), intramuscular, and intramyocellular lipid while subcutaneous fat decreases. IMAT has been associated with lower muscle strength, power, and quality, chronic inflammation, impaired glucose tolerance, and elevated total cholesterol in older adults. This review focused on trials investigating the role of age, physical activity and diet on IMAT. The studies agreed that IMAT increases with age and seems to be responsive to physical activity, particularly the combination of aerobic and resistance exercise. However, some reported this could occur with or without weight loss, and some reported that high IMAT at baseline may blunt the muscle quality adaptive response to physical training. Larger and longer trials are needed to differentiate the independent or synergistic effects of resistance and/or aerobic training, and obesity and weight loss combined with resistance, aerobic or combination of aerobic and resistance training on IMAT.

Intramuscular Fat Accumulation and Associations With Body Composition, Strength, and Physical Functioning in Patients With Rheumatoid Arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is associated with adverse body composition profiles and low muscle density due to the accumulation of intramuscular fat. Linear regression was used to assess differences between RA patients and controls and to determine associations between muscle density, strength, and physical functioning.

METHODS

Patients with RA, ages 18-70 years, and healthy control subjects underwent whole-body dual x-ray absorptiometry and peripheral quantitative computed tomography, in order to quantify the appendicular lean mass index (ALMI) and the fat mass index (FMI), visceral fat area, and muscle density. Dynamometry was used to measure hand grip strength and muscle strength at the knee and lower leg. Disability and physical functioning were measured using the Health Assessment Questionnaire (HAQ) and the Short Physical Performance Battery (SPPB). Linear regression analyses were performed to assess differences related to RA and associations between muscle density, strength, and function.

RESULTS

The study group included 103 patients with RA (51 men) and 428 healthy control subjects. Among patients with RA, low muscle density was associated with higher disease activity, C-reactive protein and interleukin-6 levels, greater total and visceral fat area, lower ALMI Z scores, physical inactivity, and long-term use of glucocorticoids (>1 year). Patients with low ALMI Z scores had lower muscle density Z scores compared with reference participants with similarly low ALMI scores. Low muscle density was independently associated with lower muscle strength, higher HAQ scores, and lower SPPB scores, after adjustment for ALMI and FMI Z scores.

CONCLUSION

The low muscle density observed in patients with RA was associated with low muscle mass, excess adiposity, poor strength, and greater disability. Interventions to address poor muscle quality could potentially affect important functional outcomes.

Cysteine- and glycine-rich protein 3 regulates glucose homeostasis in skeletal muscle

Skeletal muscle is the major site of postprandial peripheral glucose uptake, but in obesity-induced insulin-resistant states insulin-stimulated glucose disposal is markedly impaired. Despite the importance of skeletal muscle in regulating glucose homeostasis, the specific transcriptional changes associated with insulin-sensitive vs. -resistant states in muscle remain to be fully elucidated. Herein, using an RNA-seq approach we identified 20 genes differentially expressed in an insulin-resistant state in skeletal muscle, including cysteine- and glycine-rich protein 3 ( Csrp3), which was highly expressed in insulin-sensitive conditions but significantly reduced in the insulin-resistant state. CSRP3 has diverse functional roles including transcriptional regulation, signal transduction, and cytoskeletal organization, but its role in glucose homeostasis has yet to be explored. Thus, we investigated the role of CSRP3 in the development of obesity-induced insulin resistance in vivo. High-fat diet-fed CSRP3 knockout (KO) mice developed impaired glucose tolerance and insulin resistance as well as increased inflammation in skeletal muscle compared with wild-type (WT) mice. CSRP3-KO mice had significantly impaired insulin signaling, decreased GLUT4 translocation to the plasma membrane, and enhanced levels of phospho-PKCα in muscle, which all contributed to reduced insulin-stimulated glucose disposal in muscle in HFD-fed KO mice compared with WT mice. CSRP3 is a highly inducible protein and its expression is acutely increased after fasting. After 24h fasting, glucose tolerance was significantly improved in WT mice, but this effect was blunted in CSRP3-KO mice. In summary, we identify a novel role for Csrp3 expression in skeletal muscle in the development of obesity-induced insulin resistance.

Effect of Exercise Type During Intentional Weight Loss on Body Composition in Older Adults with Obesity

OBJECTIVE

To examine the long-term effects of exercise modality during weight loss on body composition and associations between body composition and physical function changes.

METHODS

Two hundred forty-nine older adults (66.9 ± 4.7 years, 71% women, 32% African American, BMI: 34.4 ± 3.7 kg/m² ) were randomized to weight loss (WL; n = 82), WL plus aerobic training (WL + AT; n = 86), or WL plus resistance training (WL + RT; n = 81) for 18 months. Dual-energy x-ray absorptiometry-acquired body composition, 400-m walk time, and knee extensor strength were measured at baseline and at 6 and 18 months.

RESULTS

Total body mass loss was enhanced when WL was combined with exercise (WL: -5.7 ± 0.7 kg, WL + AT: -8.5 ± 0.7 kg, WL + RT: -8.7 ± 0.7 kg; P < 0.01). Total body fat mass loss was significantly greater in WL + AT (-6.8 ± 0.6 kg, -16.4%) and WL + RT (-7.8 ± 0.5 kg, -19.0%) than WL (-4.8 ± 0.6 kg, -10.9%); both P < 0.01. Lean mass loss was greatest in WL + AT (-1.6 ± 0.3 kg, -3.1%) compared with WL + RT (-0.8 ± 0.3 kg, -1.5%) or WL (-1.0 ± 0.3 kg; -2.0%); both P ≤ 0.02. Change in 400-m walk time was associated with change in fat mass (β/SD = +6.1 s; P < 0.01), while change in knee extensor strength was associated with change in lean mass (β/SD = +1.6 Nm; P < 0.01).

CONCLUSIONS

WL + RT results in less lean mass lost than WL + AT; WL plus exercise yields greater fat mass loss than WL alone.

Body Composition Remodeling and Mortality: The Health Aging and Body Composition Study

BACKGROUND

Age-related losses of lean mass and shifts to central adiposity are related to functional decline and may predict mortality and/or explain part of the risk of weight loss. To determine how mortality risk is related to shifts in body composition, changes should be considered in the context of overall weight change.

METHODS

Five-year changes in body composition were assessed with computed tomography (cm2) and dual x-ray absorptiometry (kg) in 869 men and 934 women initially aged 70-79 years. All-cause mortality was monitored for up to 12 years (2002-2003 to September 30, 2014), and risk was assessed using sex-specific Cox models.

RESULTS

Both men and women lost weight, visceral fat area, thigh muscle area, lean mass, and fat mass (all p < .01) but gained intermuscular thigh fat area (p < .01). There were 995 deaths. After adjustment for total weight change, demographics, and chronic disease, losing thigh muscle area was associated with higher mortality in both men (1.21, 1.08-1.35) and women (1.18, 1.01-1.37, per 9.0cm2) and was especially strong in normal weight (body mass index < 25kg/m2) individuals and those losing weight. Losing intermuscular thigh fat was protective against mortality only in normal weight (0.66, 0.51-0.86) and weight stable men (0.79, 0.66-0.95, per 3.2cm2). Changes in visceral fat area were not associated with mortality.

CONCLUSIONS

Older adults with greater loss of thigh muscle than expected for overall weight change had a higher mortality risk compared to those with relative thigh muscle preservation, suggesting that conservation of muscle mass is important for survival in old age.

Skeletal muscle inflammation and insulin resistance in obesity

Obesity is associated with chronic inflammation, which contributes to insulin resistance and type 2 diabetes mellitus. Under normal conditions, skeletal muscle is responsible for the majority of insulin-stimulated whole-body glucose disposal; thus, dysregulation of skeletal muscle metabolism can strongly influence whole-body glucose homeostasis and insulin sensitivity. Increasing evidence suggests that inflammation occurs in skeletal muscle in obesity and is mainly manifested by increased immune cell infiltration and proinflammatory activation in intermyocellular and perimuscular adipose tissue. By secreting proinflammatory molecules, immune cells may induce myocyte inflammation, adversely regulate myocyte metabolism, and contribute to insulin resistance via paracrine effects. Increased influx of fatty acids and inflammatory molecules from other tissues, particularly visceral adipose tissue, can also induce muscle inflammation and negatively regulate myocyte metabolism, leading to insulin resistance.

The Effects of Weight and Waist Change on the Risk of Long-Term Mortality in Older Adults- The Bambuí (Brazil) Cohort Study of Aging

OBJECTIVE

We aimed to investigate the risk of long-term mortality associated with weight and waist circumference (WC) change among older adults, particularly the overweight and obese ones.

DESIGN

Cohort Study.

SETTING

The Bambuí (Brazil) Cohort Study of Aging.

PARTICIPANTS

Community-dwelling elderly (n=1138).

MEASUREMENTS

Weight and WC were reassessed three years after baseline. Mortality risk associated with a 5% weight/WC loss and gain was compared to that of weight/WC stability by Cox models adjusted for clinical, behavioral and social known risk factors for death (age, gender, BMI, smoking, diabetes, total cholesterol, hypertension, Chagas disease, major electrocardiographic changes, physical activity, B-type natriuretic peptide, C-reactive protein, creatinine, education and household income).

RESULTS

Female sex was predominant (718; 63.1%). Mean age was 68 (6.7) years. Weight stability (696; 61.1%) was more common than weight loss (251; 22.1%) or gain (191; 16.8%). WC remained stable in 422 (37.3%), decreased in 418 (37.0%) and increased in 291 (25.7%) participants. There were 334 (29.3%) deaths over a median follow-up time of 8.0 (6.4-8.0) years from weight/WC reassessment. Weight loss (HR 1.69; 95% CI 1.30-2.21) and gain (HR 1.37; 95% CI 1.01-1.85) were associated with increased mortality, except in those who were physically active in which weight gain was associated with decreased mortality. Results were similar for participants who were overweight/obese or with abdominal obesity at baseline (HR 1.41; 95%CI 1.02-1.97 and HR 2.01; 95%CI 1.29-3.12, for weight loss and gain, respectively). WC change was not significantly associated with mortality.

CONCLUSION

Although weight loss has been recommended for adults with excessive weight regardless of age, weight change might be detrimental in older adults. Rather than weight loss, clinical interventions should target healthy lifestyle behaviors that contribute to weight stability, particularly physical activity in overweight and obese older adults.

Overweight and Abdominal Obesity Association with All-Cause and Cardiovascular Mortality in the Elderly Aged 80 and Over: A Cohort Study

OBJECTIVE

To evaluate the association between overweight and abdominal obesity with all-cause and cardiovascular mortality in the elderly aged 80 and over.

DESIGN

A prospective cohort study.

SETTING

A population-based study of community-dwelling very elderly adults in a city in southern Brazil.

PARTICIPANTS

236 very elderly adults, number that represents 85% of the population aged 80 and over living in the city in the period (mean age 83.4 ± 3.2).

MEASUREMENTS

Overweight and abdominal obesity were assessed using recommended cut-off points for body mass index (BMI), waist circumference (WC), waist-hip ratio (WHR) and waist-height ratio (WHtR). The association between these anthropometric measurements and all-cause and cardiovascular mortality were independently estimated by Cox proportional hazards model. Kaplan-Meier was used to assess survival time.

RESULTS

Increased WC (>80cm F and >94cm M) and WHtR (>0.53 F and >0.52 M) were associated with lower all-cause mortality, but only WHtR remained associated even after controlling for residual confounding (HR 0.55 CI95% 0.36-0.84; p<0.001). Additionally increased WC was independently associated with lower mortality from cardiovascular diseases (HR 0.57 CI95% 0.34-0.95; p<0.030). BMI and WHR did not show significant independent association with mortality in the main analysis.

CONCLUSION

Greater abdominal fat accumulation, as estimated by WC and WHtR, presented an association with lower allcause and cardiovascular mortality in the elderly aged 80 and over, but not by BMI and WHR.

[Obesity in old age and its importance for functionality and frailty]

In later life a high body mass index (BMI) is associated with the lowest age-related mortality rate. The BMI range used by the World Health Organization (WHO) to classify overweight, a BMI of 25-30 kg/m², can be regarded as normal weight in old age; nevertheless, obesity is associated with an increased risk of disability and of a deterioration in physical functionality, particularly among older age groups. This relationship to obesity has also been established for frailty. For this reason, a reduction in weight may be appropriate under functional aspects if BMI values exceed 30 kg/m²; however, such a decision cannot be made on the basis of an individual BMI alone. The functional status, body composition, comorbidities and, in particular the life perspectives of the patient should also be taken into consideration. If weight loss is intended, it must always be performed under strict medical supervision involving optimized protein intake, a carefully calculated moderate reduction in calories and adequate physical training. In the case of chronically ill elderly patients, weight reduction is not usually appropriate. Restrictive diets of any kind should principally be critically viewed in old age because even temporary inadequate energy intake may lead to accelerated deterioration of muscle and bone structure.

Lower leg muscle density is independently associated with fall status in community-dwelling older adults

Muscle density is a risk factor for fractures in older adults; however, its association with falls is not well described. After adjusting for biologically relevant confounding factors, a unit decrease in muscle density was associated with a 17 % increase in odds of reporting a fall, independent of functional mobility.

INTRODUCTION

Falls are the leading cause of injury, disability, and fractures in older adults. Low muscle density (i.e., caused by muscle adiposity) and functional mobility have been identified as risk factors for incident disability and fractures in older adults; however, it is not known if these are also independently associated with falls. The purpose of this study was to explore the associations of muscle density and functional mobility with fall status.

METHODS

Cross-sectional observational study of 183 men and women aged 60-98 years. Descriptive data, including a 12-month fall recall, Timed Up and Go (TUG) test performance, lower leg muscle area, and density. Odds ratio (OR) of being a faller were calculated, adjusted for age, sex, body mass index, general health status, diabetes, and comorbidities.

RESULTS

Every mg/cm(3) increase in muscle density (mean 70.2, SD 2.6 mg/cm(3)) independently reduced the odds of being a faller by 19 % (OR 0.81 [95 % CI 0.67 to 0.97]), and every 1 s longer TUG test time (mean 9.8, SD 2.6 s) independently increased the odds by 17 % (OR 1.17 [95 % CI 1.01 to 1.37]). When both muscle density and TUG test time were included in the same model, only age (OR 0.93 [95 % CI 0.87 to 0.99]) and muscle density (OR 0.83 [95 % CI 0.69 to 0.99]) were independently associated with fall status.

CONCLUSIONS

Muscle density was associated with fall status, independent of functional mobility. Muscle density may compliment functional mobility tests as a biometric outcome for assessing fall risk in well-functioning older adults.

Intramuscular fat and physical performance at the Framingham Heart Study

Intramuscular fat may mediate associations between obesity and physical disability. We examined the associations between muscle attenuation, a proxy for intramuscular fat, and physical function. Paraspinous muscle computed tomography attenuation was obtained on a Framingham Heart Study subgroup (n = 1152, 56 % women, mean age 66 years). Regressions modeled cross-sectional associations between muscle attenuation and mobility disability, grip strength, and walking speed with standard covariates; models additionally adjusted for body mass index (BMI) and visceral adipose tissue (VAT). Separate models investigated associations between VAT and subcutaneous adipose tissue (SAT) and physical function. Per 1 standard deviation decrement in muscle attenuation (i.e., more muscle fat), we observed 1.29 (95 % CI = 1.11, 1.50; p = 0.0009) increased odds of walking speed ≤1 m/s in women and men. This persisted after separate BMI and VAT adjustments (p < 0.02). In men, there was a 1.29 kg (95 % CI = 0.57, 2.01; p = 0.0005) decrement in grip strength, which persisted after BMI and VAT adjustments (p ≤ 0.0004). For VAT and SAT, similar associations were not observed. Intramuscular fat is associated with increased odds of walking speed ≤1 m/s in both sexes and lower grip strength in men. There were no similar associations for VAT and SAT, highlighting the specificity of intramuscular fat in association with physical function.