Clustering of strength, physical function, muscle, and adiposity characteristics and risk of disability in older adults

Trunk-oriented Exercises Versus Whole-body Vibration on Abdominal Thickness and Balance in Children with Duchene Muscular Dystrophy

OBJECTIVES

Progressive proximal muscle weakening in children with Duchenne muscular dystrophy (DMD) impairs postural adjustments by impairing motor function and preventing ambulation. During daily activities, for gait and dynamic balance, certain postural modifications are required. The objective was to compare the impact of trunk-oriented exercises versus whole-body vibration on abdominal muscle thickness and balance in children with DMD.

METHODS

Participants in this study were 30 boys with DMD, aged 6 to 10 years old. Children were divided into two groups (A and B) randomly. Children in group (A) underwent a prescribed regimen of physical therapy along with trunk-oriented exercises, whereas group (B) received the same regimen as group (A) together with whole-body vibration three times per week for three consecutive months. Balance and the thickness of the abdominal muscles were measured using the Biodex balance system and ultrasonography, respectively, before and after therapy.

RESULTS

When compared to the pre-treatment results in both groups, the post-treatment results showed a significant difference in all measured variables (p<0.05). Post-treatment values showed that all of the measured variables significantly differed in favor of group A.

CONCLUSIONS

Trunk-oriented exercises can improve abdominal thickness and balance more effectively than whole-body vibration in children with DMD.

CLINICALTRIALS

gov ID: NCT05688072.

Lower Adherence to a Mediterranean Diet Is Associated with High Adiposity in Community-Dwelling Older Adults: Results from the Longevity Check-Up (Lookup) 7+ Project

High adiposity impacts health and quality of life in old age, owing to its association with multimorbidity, decreased physical performance, and frailty. Whether a high adherence to a Mediterranean diet (Medi-Diet) is associated with reduced body adiposity in older adults is unclear. The present study was conducted to assess the prevalence of high adiposity in a large sample of community-dwelling older adults. We also explored the relationship between whole-body adiposity estimated through relative fat mass (RFM) and Medi-Diet adherence. Data were obtained from the Longevity Check-up 7+ (Lookup7+) project database. RFM was estimated from anthropometric and personal parameters using a validated equation. RFM was categorized as high if ≥40% in women and ≥30% in men. Information on diet was collected using a food frequency questionnaire, while Medi-Diet adherence was assessed through a modified version of the Medi-Lite scoring system. Analyses were conducted in 2092 participants (mean age 73.1 ± 5.9 years; 53.4% women). Mean RFM was 39.6 ± 5.14% in women and 29.0 ± 3.6% in men. High adiposity was found in 971 (46.4%) participants and was more frequent in those with a low (54.2%) or moderate (46.4%) Medi-Diet adherence compared with the high-adherence group (39.7%, p < 0.001). Logistic regression indicated that older adults with high Medi-Diet adherence were less likely to have a high RFM. Other factors associated with a greater risk of having high adiposity were older age, female sex, and physical inactivity. Our findings support an association between healthy lifestyles, including a greater adherence to a Mediterranean-style diet, and lower body adiposity in older adults.

Higher abdominal adiposity is associated with higher lean muscle mass but lower muscle quality in middle-aged and older men and women: the Framingham Heart Study

BACKGROUND

The objective was to determine if abdominal fat is related to poor muscle health.

METHODS

This cross-sectional study included 428 males and 534 females with appendicular lean mass (ALM, kg) from dual-energy X-ray absorptiometry (DXA), grip strength (kg), and upper extremity muscle "quality" (grip strength/arm lean mass) measured (1996-2001) in the Framingham Offspring Study. Sex-specific linear regressions associated adiposity measures [waist circumference (WC, cm) and visceral adipose tissue (VAT, cm3), and subcutaneous adipose tissue (SAT, cm3)] as Z-scores with each measure of muscle, adjusting for covariates. Models were further stratified by body mass index (BMI, < 30, ≥ 30 kg/m2).

RESULTS

Mean (± SD) age was 60 ± 9 years and BMI was 28.9 ± 4.6 kg/m2 (men) and 27.7 ± 5.8 kg/m2, (women). In men, the BMI-stratified analyses showed higher WC was associated with higher ALM (P < 0.0001 each) but with lower muscle quality (P < 0.02) in both BMI groups. Higher SAT was also associated with higher ALM (P = 0.0002) and lower muscle quality (P = 0.0002) in men with BMI < 30, but not in obese men. In women, higher WC, SAT, and VAT were each associated with higher ALM but lower muscle quality, particularly in obese women. Higher SAT (P = 0.05) and VAT (P = 0.04) were associated with higher quadriceps strength in women with BMI < 30 kg/m2 but not in obese women.

CONCLUSIONS

Higher abdominal fat may be associated with greater lean mass but poorer muscle quality, particularly in obese women. This suggests that adipose tissue may have endocrine influences on muscle, which should be confirmed in longitudinal studies.

Multisystem physiological perspective of human frailty and its modulation by physical activity

"Frailty" is a term used to refer to a state characterized by enhanced vulnerability to, and impaired recovery from, stressors compared with a nonfrail state, which is increasingly viewed as a loss of resilience. With increasing life expectancy and the associated rise in years spent with physical frailty, there is a need to understand the clinical and physiological features of frailty and the factors driving it. We describe the clinical definitions of age-related frailty and their limitations in allowing us to understand the pathogenesis of this prevalent condition. Given that age-related frailty manifests in the form of functional declines such as poor balance, falls, and immobility, as an alternative we view frailty from a physiological viewpoint and describe what is known of the organ-based components of frailty, including adiposity, the brain, and neuromuscular, skeletal muscle, immune, and cardiovascular systems, as individual systems and as components in multisystem dysregulation. By doing so we aim to highlight current understanding of the physiological phenotype of frailty and reveal key knowledge gaps and potential mechanistic drivers of the trajectory to frailty. We also review the studies in humans that have intervened with exercise to reduce frailty. We conclude that more longitudinal and interventional clinical studies are required in older adults. Such observational studies should interrogate the progression from a nonfrail to a frail state, assessing individual elements of frailty to produce a deep physiological phenotype of the syndrome. The findings will identify mechanistic drivers of frailty and allow targeted interventions to diminish frailty progression.

Determinants of muscle density and clinical outcomes: Findings from the Hertfordshire Cohort Study

PURPOSE

The age-related loss of skeletal muscle mass and strength is associated with adverse health outcomes. However, to date, peripheral quantitative computed tomography (pQCT)-derived muscle density has been little studied. We used a well characterised cohort of older adults to identify lifestyle and anthropometric determinants of pQCT-derived muscle density measured 11 years later, and to report relationships between pQCT-derived muscle density with history of falls and prevalent fractures.

METHODS

A lifestyle questionnaire was administered to 197 men and 178 women, aged 59-70 at baseline. After a median of 11.5 (IQR 10.9, 12.3) years, pQCT (Stratec XCT2000) of the radius and tibia was performed to measure forearm muscle density (FMD) and calf muscle density (CMD). Presence of falls and fractures since the age of 45 were determined through participant recall; vertebral fractures were also ascertained through vertebral fracture assessment using iDXA. Total hip BMD (TH aBMD) was assessed using DXA. Baseline characteristics in relation to muscle density at follow-up were examined using linear regression; associations between muscle density and prior falls and fractures were investigated using logistic regression. All analyses were adjusted for sex and age.

RESULTS

Mean (SD) age at muscle density measurement was 76.3 (2.6) years. Mean (SD) FMD was 79.9 (3.1) and 77.2 (3.2) among males and females, respectively; CMD was 80.7 (2.6) and 78.5 (2.6) among males and females, respectively. Significant sex-differences in muscle density were observed at each site (p < 0.001). Female sex, lower weight, and lower body mass index were associated (p < 0.05) with both lower FMD and CMD. Additional correlates of lower CMD included older age and shorter stature. Lifestyle measures were not associated with muscle density in this cohort. Lower FMD was related to increased risk of previous fracture (odds ratio (95 % CI) per SD lower FMD: 1.42 (1.07, 1.89), p = 0.015) but not after adjustment for TH aBMD (p > 0.08). No significant relationships were seen between muscle density and falls.

CONCLUSION

Female sex, older age, and lower BMI were associated with subsequent lower muscle density in older community-dwelling adults. Lower FMD was related to increased risk of previous fracture. Changes in muscle density over time might precede adverse outcomes such as falls and fractures and may be a long-term predictor of frailty. It could be also suggested that muscle density could be a more clinically meaningful surrogate of functional decline and disability than muscle size or mass, but more studies are needed to support this notion.

Self-Organizing Maps to Multidimensionally Characterize Physical Profiles in Older Adults

The aim of this study is to automatically analyze, characterize and classify physical performance and body composition data of a cohort of Mexican community-dwelling older adults. Self-organizing maps (SOM) were used to identify similar profiles in 562 older adults living in Mexico City that participated in this study. Data regarding demographics, geriatric syndromes, comorbidities, physical performance, and body composition were obtained. The sample was divided by sex, and the multidimensional analysis included age, gait speed over height, grip strength over body mass index, one-legged stance, lean appendicular mass percentage, and fat percentage. Using the SOM neural network, seven profile types for older men and women were identified. This analysis provided maps depicting a set of clusters qualitatively characterizing groups of older adults that share similar profiles of body composition and physical performance. The SOM neural network proved to be a useful tool for analyzing multidimensional health care data and facilitating its interpretability. It provided a visual representation of the non-linear relationship between physical performance and body composition variables, as well as the identification of seven characteristic profiles in this cohort.

Factor analysis to determine relative contributions of strength, physical performance, body composition and muscle mass to disability and mobility disability outcomes in older men

BACKGROUND

It is not known how measures of body composition, strength and physical performance are interrelated or how empirical groupings of these measures relate to disability and mobility disability.

METHODS

Muscle mass was assessed by D3-creatine dilution (D3Cr muscle mass) in 1345 men (84.1 ± 4.1 years) enrolled in the Osteoporotic Fractures in Men (MrOS) study. Participants completed anthropomorphic measures, walk speed, grip strength, chair stands, and dual x-ray absorptiometry (DXA) estimated appendicular lean mass (ALM) and body fat percentage. Men reported limitations in mobility, activities of daily living (ADLs) and instrumental ADLs at initial and over 2.2 ± 0.3 years. Factor analysis reduced variables into related groups and negative binomial models calculated relative risk (RR) of factors with mobility and disability outcomes.

RESULTS

Factor analysis reduced 10 variables into four factors: Factor 1, body composition, including ALM, body fat percentage, weight and muscle mass; Factor 2, body size and lean mass, including height, weight and ALM; Factor 3, muscle mass, strength and performance, including walk speed, chair stands, grip strength, and muscle mass; and Factor 4, lean mass and weight, including ALM and weight. Only Factor 3 was significantly associated (p-value < .001) with prevalent disability (RR per standard deviation increment in factor score (reflecting higher muscle mass, strength and physical performance) 0.44, 0.35-0.56) and mobility disability (RR 0.22, 0.17 0.28), and incident mobility disability (RR 0.37, 0.27-0.50).

CONCLUSION

D3Cr muscle mass was the only body composition variable that co-segregated with strength and physical performance measures, and contributed to a factor that was associated with disability outcomes in older men.

Comparison of the efficacy of two interventions in ameliorating abdominal thickness and sitting function in children with diplegia

Objective/Background

The abdominal muscles are extremely important in stabilizing the trunk and maximizing postural stability. The presence of apparent stiffness in children with spastic diplegia is associated with unsteadiness, impaired walking, and pelvic malrotation. The aim of this study was to compare the efficacy of hippotherapy and whole-body vibration in ameliorating abdominal muscle thickness and sitting function in children with diplegia.

Methods

A total of 60 children with spastic diplegia were selected from the Faculty of Physical Therapy's outpatient clinic, Cairo University, and randomly allocated into two groups. Group A received conventional physical therapy for 1 h in addition to whole-body vibration, whereas group B received hippotherapy for 40 min. The same designed physical therapy program was administered for 12 weeks, three times per week, in both groups. Ultrasonography was used to measure abdominal thickness, and Gross Motor Function Measurement-88 was used to measure functional ability.

Results

A significant improvement in abdominal muscle thickness and sitting function (p < 0.05) was observed in both groups, and greater improvements were observed in group B.

Conclusion

Whole-body vibration and hippotherapy training may be recommended to facilitate sitting function and ameliorate abdominal thickness in children with diplegia. Hippotherapy is more effective than whole-body vibration in improving sitting function and abdominal muscle thickness.

Functional capacity and risk of frailty syndrome in 85-year-old and older women living in nursing homes in Poland

Maintaining sufficient physical fitness to prevent any limitations in performing activities of daily living and to be functionally independent is of great importance for both longevity and quality of life in older adults. Aim of the study was to evaluate functional physical fitness of women aged 85 years and older, residents of nursing homes, in the Polish population and to assess the risk of frailty syndrome. The study involved 17 women aged 85 years or older, residents of nursing homes in the Lower Silesian voivodeship. The Senior Fitness Test was used to assess functional fitness. The results of functional fitness tests were related to the standards for the elderly population in Poland and to the reference standards for maintaining independence. In addition, hand grip strength level was measured using a hand dynamometer, height and weight were measured, and BMI was calculated. 15-item version of the Geriatric Depression Scale was used to assess the level of depression. We used 3 of the 5 proposed criteria from the Cardiovascular Health Study Frailty Index to assess the presence of frailty syndrome: gait speed, level of hand grip strength, and the presence of depression. The results of the Senior Fitness Test demonstrate the low level of functional fitness of female nursing home residents. A large percentage of the women surveyed are below the standard values developed for Polish seniors. The weakest results were in the timed up and go test, with more than 94% of the women tested falling outside the standard ranges. The mean results of all samples do not meet the developed reference standards for maintaining independence. No non-frail person was found among the study participants and the vast majority were at risk for frailty syndrome. Most of the studied women do not meet functional fitness standards developed for the Polish population, as well as reference standards for maintaining independence. Nursing home residents over the age of 85 are at risk for frailty syndrome.

Peripheral bone structure, geometry, and strength and muscle density as derived from peripheral quantitative computed tomography and mortality among rural south Indian older adults

Multiple studies have observed a relationship of bone mineral density (BMD) measured by Dual energy X-ray absorptiometry (DXA) and mortality. However, areal BMD (aBMD) measured by DXA is an integrated measure of trabecular and cortical bone and does not measure the geometry of bone. Peripheral Quantitative Computed Tomography (pQCT) provides greater insights on bone structure, geometry and strength. To examine whether higher bone phenotypes and muscle density as measured by pQCT are associated with a lower all-cause mortality, we studied 245 men and 254 women (all age >60) recruited in the Mobility and Independent Living among Elders Study in rural south India. Cox proportional hazards models estimated hazard ratios (HR [95% Confidence Intervals]). After an average follow-up of 5.3 years, 73 men and 50 women died. Among men, trabecular volumetric bone mineral density (vBMD) of radius (HR per SD increase in parameter = 0.59 [0.43, 0.81]) and tibia (0.60[0.45, 0.81]), cortical vBMD of radius (0.61, [0.47, 0.79]) and tibia (0.62, [0.49, 0.79]), cortical thickness of radius (0.55, [0.42, 0.7]) and tibia (0.60, [0.47, 0.77]), polar strength strain index (SSIp) of tibia (0.73 [0.54, 0.98]), endosteal circumference of radius (1.63, [1.25, 2.12]) and tibia (1.54, [1.19, 1.98]) were associated with all-cause mortality. Muscle density (0.67, [0.51, 0.87]) was associated with lower mortality in men. Among women cortical vBMD of radius (0.64, [0.47, 0.87]) and tibia (0.60 [0.45, 0.79]), cortical thickness of radius (0.54, [0.37, 0.79]) and tibia (0.43, [0.30, 0.61]), SSIp of radius (0.70 [0.48,1.01]) and tibia (0.58 [0.37, 0.90]) and endosteal circumference of radius (1.33 [0.97, 1.82]) and tibia (1.83, [1.37, 2.45]) were associated with all-cause mortality. Among men, gait speed mediated the association of muscle density and mortality but there was no mediation for any bone parameters. Conclusion: pQCT bone measures and muscle density were independently associated with mortality among rural south Indian elders.

Higher Serum Leptin Levels are Associated with a Reduced Risk of Sarcopenia but a Higher Risk of Dynapenia Among Older Adults

Background

Leptin plays an important role in regulating the energy homeostasis of fat and muscle. Paradoxical findings existed between serum leptin levels and muscle health conditions. Here, we aimed to investigate the relationship between serum leptin levels and the risk of sarcopenia or dynapenia among older adults.

Methods

Adults aged 65 and older living in the community were recruited at annual health checkups. Body composition, gait speed, and handgrip strength were examined. The cutoff values of muscle mass and strength to define sarcopenia and dynapenia were based on the consensus by the Asia Working Group of Sarcopenia in 2019. Serum leptin level was measured by an immunoassay.

Results

Four hundred sixty participants (55.65% females) were enrolled. There were 16.08% and 23.91% with sarcopenia and dynapenia, respectively. Higher serum leptin levels were positively associated with muscle and fat mass but negatively associated with handgrip strength and gait speed for both sexes. In the logistic regression models adjusted for various confounders, a higher serum leptin level was associated with an increased risk of dynapenia with dose-response effects among both male and female participants (odds ratio [OR]=3.74, 95% confidence interval [CI]= 0.99–14.17; OR= 3.32, 95% CI=1.03–10.74, respectively), and a positive trend existed in both genders (p for trend=0.040 and 0.042, respectively). In contrast, a higher leptin level was associated with a reduced risk of sarcopenia with dose-response trends for both sexes (OR= 0.06, 95% CI=0.01–0.48; OR= 0.26, 95% CI=0.06–1.17, respectively) in models of multivariate logistic regression analyses, and a negative trend existed in both genders (p for trend = 0.002 and 0.023, respectively).

Conclusion

A positive trend existed between the serum leptin level and the dynapenia risk, whereas it revealed a negative trend in the serum leptin level and sarcopenia risk in both male and female elderly individuals. The biological mechanisms underlying its negative association with muscle strength but its positive association with muscle mass warrants further investigation.

Efficacy of Creatine Supplementation and Resistance Training on Area and Density of Bone and Muscle in Older Adults

PURPOSE

To examine the efficacy of creatine (Cr) supplementation and any sex differences during supervised whole-body resistance training (RT) on properties of bone and muscle in older adults.

METHODS

Seventy participants (39 men, 31 women; mean age ± standard deviation: 58 ± 6 yr) were randomized to supplement with Cr (0.1 g·kg-1·d-1) or placebo (Pl) during RT (3 d·wk-1 for 1 yr). Bone geometry (radius and tibia) and muscle area and density (forearm and lower leg) were assessed using peripheral quantitative computed tomography.

RESULTS

Compared with Pl, Cr increased or maintained total bone area in the distal tibia (Cr, Δ +17 ± 27 mm2; Pl, Δ -1 ± 22 mm2; P = 0.031) and tibial shaft (Cr, Δ 0 ± 9 mm2; Pl, Δ -5 ± 7 mm2; P = 0.032). Men on Cr increased trabecular (Δ +28 ± 31 mm2; P < 0.001) and cortical bone areas in the tibia (Δ +4 ± 4 mm2; P < 0.05), whereas men on Pl increased trabecular bone density (Δ +2 ± 2 mg·cm-3; P < 0.01). There were no bone changes in the radius (P > 0.05). Cr increased lower leg muscle density (Δ +0.83 ± 1.15 mg·cm-3; P = 0.016) compared with Pl (Δ -0.16 ± 1.56 mg·cm-3), with no changes in the forearm muscle.

CONCLUSIONS

One year of Cr supplementation and RT had some favorable effects on measures of bone area and muscle density in older adults.

CT muscle density, D3Cr muscle mass and body fat associations with physical performance, mobility outcomes and mortality risk in older men

BACKGROUND

Muscle mass declines with age, while body adiposity increases. Sarcopenic obesity has been proposed to be particularly deleterious. However, previous methods for estimating muscle mass have been inadequate, and the relative contributions of total body fat vs. muscle fat to adverse outcomes have been unclear.

METHODS

In a large cohort of older men (N= 1017), we measured muscle mass (D3 creatine dilution), muscle density (high resolution peripheral computed tomography in the diaphyseal tibia) as a proxy of muscle fat, and total body fat (dual energy x-ray absorptiometry). We examined their associations with physical performance (walking speed, grip strength, chair stand time), the risk of mobility outcomes (mobility limitations, mobility disability), and the risk of death over ~5 years.

RESULTS

In combined models, lower muscle mass and muscle density were independently associated with worse physical performance and the risk of adverse outcomes, while total body fat was minimally related to physical performance and not related to mobility outcomes or mortality. For example, the relative risks for mortality per 1 standardized unit increase in muscle density, muscle mass, and total body fat were 0.84 (95% CI: 0.74, 0.70), 0.70 (0.57, 0.86), and 0.90 (0.64, 1.25), respectively.

CONCLUSIONS

Muscle mass and muscle density were associated with physical performance and adverse outcomes, and had independent, additive effects. There was little additional contribution of total body fat.

Peripheral Quantitative Computed Tomography Derived Muscle Density Is Associated With Physical Performance in Older Adults

PURPOSE

The assessment of body composition is an integral part in diagnosing sarcopenia. The purpose of this study was to determine the relationships between peripheral quantitative computed tomography (pQCT)-derived measures of body composition and measures of physical performance in older adults.

METHODS

Muscle density, muscle area, and fat area of 168 patients aged 65 years and older (76.3±6.5) were measured with pQCT at the distal forearm additionally to clinical assessment consisting of medical history, physical examination and physical assessment including hand grip strength, gait speed and chair rise tests. Regression analyses assessed associations between patients' physical performance and pQCT derived data.

RESULTS

Among the three pQCT parameters, especially muscle density was significantly correlated with all of the three measures of physical performance even after adjusting for sex, age, BMI, vitamin D serum level and the level of physical activity. The same analysis for muscle area achieved significance level only for handgrip strength but not for gait speed nor for chair rise time. Fat area was significantly correlated only with gait speed after adjusting for sex and age. The association of muscle density with physical performance held up in an additional subanalysis stratified by body mass index.

CONCLUSION

Muscle density, a proxy for muscle fat infiltration, seems to be better than muscle area or fat area at assessing muscle quality and physical performance in older adults. This association seems to be independent of the body mass index.

Metabolic syndrome and the benefit of a physical activity intervention on lower-extremity function: Results from a randomized clinical trial

BACKGROUND

In older adults, increases in physical activity may prevent decline in lower-extremity function, but whether the benefit differs according to metabolic syndrome (MetS) status is uncertain. We aim to investigate whether structured physical activity is associated with less decline in lower-extremity function among older adults with versus without MetS.

METHODS

We used data from the multicenter Lifestyle Interventions and Independence for Elders (LIFE) study to analyze 1535 sedentary functionally-vulnerable women and men, aged 70 to 89 years old, assessed every 6 months (February 2010-December 2013) for an average of 2.7 years. Participants were randomized to a structured, moderate-intensity physical activity intervention (PA; n = 766) or health education program (HE; n = 769). MetS was defined according to the 2009 multi-agency harmonized criteria. Lower-extremity function was assessed by 400-m walking speed and the Short Physical Performance Battery (SPPB) score.

RESULTS

763 (49.7%) participants met criteria for MetS at baseline. Relative to HE, PA was associated with faster 400-m walking speed among participants with MetS (P < 0.001) but not among those without MetS (P = 0.91), although the test for statistical interaction was marginally non-significant (P = 0.07). In contrast, no benefit of PA versus HE was observed on the SPPB score in either MetS subgroup.

CONCLUSIONS

Among older adults at high risk for mobility disability, moderate-intensity physical activity conveys significant benefits in 400-m walking speed but not SPPB in those with, but not without, MetS. The LIFE physical activity program may be an effective strategy for maintaining or improving walking speed among vulnerable older adults with MetS.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01072500.

IGF-I/IGFBP3/ALS Deficiency in Sarcopenia: Low GHBP Suggests GH Resistance in a Subgroup of Geriatric Patients

CONTEXT

Definition of etiological subgroups of sarcopenia may help to develop targeted treatments. insulin like growth factor-I (IGF-I), Insulinlike growth factor binding protein 3 (IGFBP3), and acid labile subunit (ALS) build a ternary complex that mediates growth hormone (GH) effects on peripheral organs, such as muscle. Low GH binding protein (GHBP) as a marker of GH receptor number would hint toward GH resistance.

OBJECTIVE

We aimed to analyze the association of IGF-I, IGFBP3, and ALS with sarcopenia.

STUDY PARTICIPANTS AND SETTING

A total of 131 consecutively recruited patients of a geriatric ward were included in a single-center cross-sectional analysis; the nonsarcopenic patients served as controls.

METHODS

Measures included sarcopenia status by hand-grip strength measurement and Skeletal Muscle Index (SMI); IGF-I, IGFBP3, ALS, GH, GHBP; body mass index (BMI); Activity of Daily Living (ADL); Mini-Mental State Examination (MMSE); routine laboratory parameters; and statistical regression modeling.

RESULTS

Compared with controls, sarcopenic patients did not differ regarding age, sex, ADL, MMSE, C-reactive protein, glomerular filtration rate, and albumin serum concentrations. However, sarcopenic patients had significantly lower IGF-I, IGFBP3, and ALS. IGF-I and ALS associated significantly with sarcopenia and low hand-grip strength, even after adjustment for age, sex, BMI, and albumin, but not with low SMI. GHBP serum was low in sarcopenic patients, but normal in geriatric patients without sarcopenia. Over 60% of patients with IGF-I/ALS deficiency patients showed GH resistance.

CONCLUSIONS

Our data suggest that in geriatric patients, low IGF-I/IGFBP3/ALS could be evaluated for causative connection of the sarcopenia spectrum. Low GHBP points toward potential GH resistance as one possible explanation of this deficiency.

Effect of whole-body vibration on abdominal thickness and sitting ability in children with spastic diplegia

Objective

Reduced muscle and bone mass, improper muscle function, and varying degrees of mobility dysfunctions are the main complications of cerebral palsy (CP). Many children with CP also present with poor abdominal muscle activation. Whole-body vibration (WBV) is a unique approach for enhancing strength and motor abilities in several clinical conditions. This study aimed to determine the influence of a 12-week WBV intervention on the thickness of the abdominal muscles and the sitting ability of children with diplegia.

Methods

A total of 30 children with spastic diplegic CP (aged 4–6 years) were randomly divided into two groups (control and experimental). The control group received a selected physical therapy program for 1 h, and the study group received WBV training for 10 min in addition to the same selected program for the control group for 3 times/week over a period of 12 weeks. Thereafter, abdominal muscle thickness and sitting ability were measured using ultrasonography and the Gross Motor Function Measure-88 (GMFM-88, sitting domain).

Results

Post treatment values revealed significant improvement in the measured variables in favour of the experimental group (p < 0.05), as there was improvement in the thickness of the four abdominal muscles compared to the control group (external oblique: F = 38.783; internal oblique: F = 99.547; transverse abdominis: F = 111.557, and rectus abdominis: F = 129.940, p < 0.05). Additionally, the study group showed a significantly greater improvement in GMFM-88 values compared to the control group (F = 129.940, p < 0.05).

Conclusion

WBV can be a viable strategy for improving sitting ability and abdominal muscle thickness among children with spastic diplegia.

Physical Activity Trajectories and Associated Changes in Physical Performance in Older Men: The MrOS Study

BACKGROUND

Physical activity (PA) is important to maintaining functional independence. It is not clear how patterns of change in late-life PA are associated with contemporaneous changes in physical performance measures.

METHODS

Self-reported PA, gait speed, grip strength, timed chair stand, and leg power were assessed in 3,865 men aged ≥ 65 years at baseline (2000-2002) and Year 7 (2007-2009). Group-based trajectory modeling, using up to four PA measures over this period, identified PA trajectories. Multivariate linear regression models (adjusted least square mean [95% confidence interval {CI}]) described associations between-PA trajectories and concurrent changes in performance.

RESULTS

Three discrete PA patterns were identified, all with declining PA. Linear declines in each performance measure (baseline to Year 7) were observed across all three PA groups, but there was some variability in the rate of decline. Multivariate models assessing the graded response by PA trajectory showed a trend where the high-activity group had the smallest declines in performance while the low-activity group had the largest (p-for trend < .03). Changes in the high-activity group were the following: gait speed (-0.10 m/s [-0.12, -0.08]), grip strength (-3.79 kg [-4.35, -3.23]), and chair stands (-0.38 [-0.50, -0.25]), whereas changes in the low-activity group were the following: gait speed (-0.16 [-0.17, -0.14]), grip strength (-4.83 kg [-5.10, -4.55]), and chair stands (-0.53 [-0.59, -0.46]). Between-group differences in leg power trajectories across PA patterns were not significant.

CONCLUSIONS

Declines in functional performance were higher among those with lower PA trajectories, providing further evidence for the interrelationship between changes in PA and performance during old age.

Skeletal Muscle Mitochondrial Dysfunction Is Present in Patients with CKD before Initiation of Maintenance Hemodialysis

BACKGROUND AND OBJECTIVES

Patients with CKD suffer from frailty and sarcopenia, which is associated with higher morbidity and mortality. Skeletal muscle mitochondria are important for physical function and could be a target to prevent frailty and sarcopenia. In this study, we tested the hypothesis that mitochondrial dysfunction is associated with the severity of CKD. We also evaluated the interaction between mitochondrial function and coexisting comorbidities, such as impaired physical performance, intermuscular adipose tissue infiltration, inflammation, and oxidative stress.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Sixty-three participants were studied, including controls (n=21), patients with CKD not on maintenance hemodialysis (CKD 3-5; n=20), and patients on maintenance hemodialysis (n=22). We evaluated in vivo knee extensors mitochondrial function using ³¹P magnetic resonance spectroscopy to obtain the phosphocreatine recovery time constant, a measure of mitochondrial function. We measured physical performance using the 6-minute walk test, intermuscular adipose tissue infiltration with magnetic resonance imaging, and markers of inflammation and oxidative stress in plasma. In skeletal muscle biopsies from a select number of patients on maintenance hemodialysis, we also measured markers of mitochondrial dynamics (fusion and fission).

RESULTS

We found a prolonged phosphocreatine recovery constant in patients on maintenance hemodialysis (53.3 [43.4-70.1] seconds, median [interquartile range]) and patients with CKD not on maintenance hemodialysis (41.5 [35.4-49.1] seconds) compared with controls (38.9 [32.5-46.0] seconds; P=0.001 among groups). Mitochondrial dysfunction was associated with poor physical performance (r=0.62; P=0.001), greater intermuscular adipose tissue (r=0.44; P=0.001), and increased markers of inflammation and oxidative stress (r=0.60; P=0.001). We found mitochondrial fragmentation and increased content of dynamin-related protein 1, a marker of mitochondrial fission, in skeletal muscles from patients on maintenance hemodialysis (0.86 [0.48-1.35] arbitrary units (A.U.), median [interquartile range]) compared with controls (0.60 [0.24-0.75] A.U.).

CONCLUSIONS

Mitochondrial dysfunction is due to multifactorial etiologies and presents prior to the initiation of maintenance hemodialysis, including in patients with CKD stages 3-5.

Association of change in muscle mass assessed by D3 -creatine dilution with changes in grip strength and walking speed

BACKGROUND

Muscle mass declines with age. However, common assessments used to quantify muscle mass are indirect. The D₃ -creatine (D₃ Cr) dilution method is a direct assessment of muscle mass; however, longitudinal changes have not been examined in relation to changes in other measures of muscle mass, strength, and performance.

METHODS

A convenience sample of 40 men from the Osteoporotic Fractures in Men Study (mean age = 83.3 years, standard deviation = 3.9) underwent repeat assessment of D₃ Cr muscle mass, dual-energy X-ray absorptiometry (DXA) lean mass, grip strength, and walking speed at two time points approximately 1.6 years apart (2014-2016). One-sample t-tests and Pearson correlations were used to examine changes in DXA total body lean mass, DXA appendicular lean mass/height² , DXA appendicular lean mass/weight, D₃ Cr muscle mass, D₃ Cr muscle mass/weight, grip strength, walking speed, and weight.

RESULTS

D₃ -creatine muscle mass, D₃ Cr muscle mass/weight, grip strength, and walking speed all significantly declined (all P < 0.01). The change in DXA measures of lean mass was moderately correlated with changes in D₃ Cr muscle mass. There was no significant correlation between the change in DXA measures of lean mass and change in walking speed (all P > 0.05). The change in D₃ Cr muscle mass/weight was moderately correlated with change in walking speed (r = 0.33, P < .05). The change in grip strength was weakly correlated with the change in DXA measures of lean mass and D₃ Cr muscle mass (r = 0.19-0.32).

CONCLUSIONS

The results of our study provide new insights regarding the decline in muscle strength and D₃ Cr muscle mass. The D₃ Cr method may be a feasible tool to measure declines in muscle mass over time.

Relationship of Physical Function to Single Muscle Fiber Contractility in Older Adults: Effects of Resistance Training With and Without Caloric Restriction

BACKGROUND

Previous studies support beneficial effects of both resistance exercise training (RT) and caloric restriction (CR) on skeletal muscle strength and physical performance. The goal of this study was to determine the effects of adding CR to RT on single-muscle fiber contractility responses to RT in older overweight and obese adults.

METHODS

We analyzed contractile properties in 1,253 single myofiber from muscle biopsies of the vastus lateralis, as well as physical performance and thigh muscle volume, in 31 older (65-80 years), overweight or obese (body mass index = 27-35 kg/m2) men (n = 19) and women (n = 12) who were randomly assigned to a standardized, progressive RT intervention with CR (RT+CR; n = 15) or without CR (RT; n = 16) for 5 months.

RESULTS

Both interventions evoked an increase in force normalized to cross-sectional area (CSA), in type-I and type-II fibers and knee extensor quality. However, these improvements were not different between intervention groups. In the RT group, changes in total thigh fat volume inversely correlated with changes in type-II fiber force (r = -.691; p = .019). Within the RT+CR group, changes in gait speed correlated positively with changes in type-I fiber CSA (r = .561; p = .030). In addition, increases in type-I normalized fiber force were related to decreases in thigh intermuscular fat volume (r = -0.539; p = .038).

CONCLUSION

Single muscle fiber force and knee extensor quality improve with RT and RT+CR; however, CR does not enhance improvements in single muscle fiber contractility or whole muscle in response to RT in older overweight and obese men and women.

The Musculoskeletal Health Benefits of Tennis

BACKGROUND

The prevalence of musculoskeletal (MSK) conditions is increasing, and although current guidelines for physical activity attempt to combat this, many fail to achieve the recommended targets. The present study sought to investigate whether regular tennis participation is more effective at enhancing MSK function than meeting the current international physical activity guidelines.

HYPOTHESIS

Tennis players will display significantly enhanced MSK function when compared with age-matched healthy active nonplayers.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Ninety participants (age range, 18-65 years) took part in this study; there were 43 tennis players (18 men, 25 women) and 47 nonplayers (26 men, 21 women). MSK function was assessed by cluster analysis of 3 factors: (1) electromyographic fatigability of prime movers during handgrip, knee extension, and knee flexion; (2) isometric strength in the aforementioned movements; and (3) body composition measured by bioelectrical impedance analysis. Maximal oxygen uptake was also assessed to characterize cardiorespiratory fitness.

RESULTS

Tennis players displayed significantly greater upper body MSK function than nonplayers when cluster scores of body fat percentage, handgrip strength, and flexor carpi radialis fatigue were compared by analysis of covariance, using age as a covariate (tennis players, 0.33 ± 1.93 vs nonplayers, -0.26 ± 1.66; P < 0.05). Similarly, tennis players also demonstrated greater lower extremity function in a cluster of body fat percentage, knee extension strength, and rectus femoris fatigue (tennis players, 0.17 ± 1.76 vs nonplayers, -0.16 ± 1.70; P < 0.05).

CONCLUSION

The present study offers support for improved MSK functionality in tennis players when compared with age-matched healthy active nonplayers. This may be due to the hybrid high-intensity interval training nature of tennis.

CLINICAL RELEVANCE

The findings suggest tennis is an excellent activity mode to promote MSK health and should therefore be more frequently recommended as a viable alternative to existing physical activity guidelines.

A guide for using NIH Image J for single slice cross-sectional area and composition analysis of the thigh from computed tomography

Reports using computed tomography (CT) to estimate thigh skeletal muscle cross-sectional area and mean muscle attenuation are often difficult to evaluate due to inconsistent methods of quantification and/or poorly described analysis methods. This CT tutorial provides step-by-step instructions in using free, NIH Image J software to quantify both muscle size and composition in the mid-thigh, which was validated against a robust commercially available software, SliceOmatic. CT scans of the mid-thigh were analyzed from 101 healthy individuals aged 65 and older. Mean cross-sectional area and mean attenuation values are presented across seven defined Hounsfield unit (HU) ranges along with the percent contribution of each region to the total mid-thigh area. Inter-software correlation coefficients ranged from R² = 0.92–0.99 for all specific area comparisons measured using the Image J method compared to SliceOmatic. We recommend reporting individual HU ranges for all areas measured. Although HU range 0–100 includes the majority of skeletal muscle area, HU range -29 to 150 appears to be the most inclusive for quantifying total thigh muscle. Reporting all HU ranges is necessary to determine the relative contribution of each, as they may be differentially affected by age, obesity, disease, and exercise. This standardized operating procedure will facilitate consistency among investigators reporting computed tomography characteristics of the thigh on single slice images.

Trial Registration: ClinicalTrials.gov NCT02308228.

Recent Progress in Sarcopenia Research: a Focus on Operationalizing a Definition of Sarcopenia

PURPOSE OF REVIEW

To discuss recent progress in sarcopenia research and to highlight controversies in the field particularly around reaching consensus on a definition of sarcopenia.

RECENT FINDINGS

Accordingly, this review begins with a discussion of the increasing awareness of this condition; briefly describes evolving definitions of sarcopenia; suggests a framework for consistent terminology for sarcopenia; discusses outstanding issues in the definition of sarcopenia; and reviews the association between sarcopenia and adverse outcome in older adults. In addition, the role of sarcopenia in other diseases is discussed. The field of sarcopenia continues to hold considerable promise and work continues to resolve outstanding concerns in this field with a unifying consensus definition on the horizon.

The effect of whole-body vibration training on lean mass: A PRISMA-compliant meta-analysis

BACKGROUND

Whole-body vibration training (WBVT) confers a continuous vibration stimuli to the body. Although some reports have discussed the effects of whole-body vibration (WBV) on bone mineral density and muscle strength, study of WBV effects on lean mass have not been determined. The purpose of the present meta-analysis was to evaluate published, randomized controlled trials (RCTs) that investigated the effects of WBVT on lean mass.

METHODS

We identified only RCTs by searching databases, including Web of Science, PubMed, Scopus, Embase, and the Cochrane Library from inception to March 2017. Data extraction, quality assessment, and meta-analysis were performed.

RESULTS

Ten RCTs with 5 RCTs concentrating on older people, 3 on young adults, and 2 on children and adolescents were included. We additionally explored the effect of WBVT on postmenopausal women (6 trials from the 10 trials). Significant improvements in lean mass with WBVT were merely found in young adults (P = .02) but not in other populations compared to control group.

CONCLUSION

The effect of WBVT found in the present meta-analysis may be used in counteracting the loss of muscle mass in younger adults. Moreover, optimal WBVT protocols for greater muscle hypertrophy are expected to be investigated.

Cushing's syndrome: a model for sarcopenic obesity

PURPOSE

Obesity and its metabolic impairments are discussed as major risk factors for sarcopenia leading to sarcopenic obesity. Cushing's syndrome is known to be associated with obesity and muscle atrophy. We compared Cushing's syndrome with matched obese controls regarding body composition, physical performance, and biochemical markers to test the hypothesis that Cushing's syndrome could be a model for sarcopenic obesity.

METHODS

By propensity score matching, 47 controls were selected by body mass index and gender as obese controls. Fat mass and muscle mass were measured by bioelectrical impedance analysis. Muscle function was assessed by chair rising test and hand grip strength. Biochemical markers of glucose and lipid metabolism and inflammation (hsCRP) were measured in peripheral blood.

RESULTS

Muscle mass did not differ between Cushing's syndrome and obese controls. However, Cushing's syndrome patients showed significantly greater chair rising time (9.5 s vs. 7.3 s, p = 0.008) and significantly lower hand grip strength (32.1 kg vs. 36.8 kg, p = 0.003). Cushing's syndrome patients with impaired fasting glucose have shown the highest limitations in hand grip strength and chair rising time.

CONCLUSIONS

Similar to published data in ageing medicine, Cushing's syndrome patients show loss of muscle function that cannot be explained by loss of muscle mass. Impaired muscle quality due to fat infiltration may be the reason. This is supported by the observation that Cushing's syndrome patients with impaired glucose metabolism show strongest deterioration of muscle function. Research in sarcopenic obesity in elderly is hampered by confounding comorbidities and polypharmacy. As Cushing's syndrome patients are frequently free of comorbidities and as Cushing's syndrome is potentially curable we suggest Cushing's syndrome as a clinical model for further research in sarcopenic obesity.

Muscle and Myotendinous Tissue Properties at the Distal Tibia as Assessed by High-Resolution Peripheral Quantitative Computed Tomography

High-resolution peripheral quantitative computed tomography (HR-pQCT) quantifies bone microstructure and density at the distal tibia where there is also a sizable amount of myotendinous (muscle and tendon) tissue (M_T); however, there is no method for the quantification of M_T. This study aimed (1) to assess the feasibility of using HR-pQCT distal tibia scans to estimate M_T properties using a custom algorithm, and (2) to determine the relationship between M_T properties at the distal tibia and mid-leg muscle density (MD) obtained from pQCT. Postmenopausal women from the Hamilton cohort of the Canadian Multicenter Osteoporosis Study had a single-slice (2.3 ± 0.5 mm) 66% site pQCT scan measuring muscle cross-sectional area (MCSA) and MD. A standard HR-pQCT scan was acquired at the distal tibia. HR-pQCT-derived M_T cross-sectional area (M_TCSA) and M_T density (M_TD) were calculated using a custom algorithm in which thresholds (34.22-194.32 mg HA/cm³) identified muscle seed volumes and were iteratively expanded. Pearson and Bland-Altman plots were used to assess correlations and systematic differences between pQCT- and HR-pQCT-derived muscle properties. Among 45 women (mean age: 74.6 ± 8.5 years, body mass index: 25.9 ± 4.3 kg/m²), M_TD was moderately correlated with mid-leg MD across the 2 modalities (r = 0.69-0.70, p < 0.01). Bland-Altman analyses revealed no evidence of directional bias for M_TD-MD. HR-pQCT and pQCT measures of M_TCSA and MCSA were moderately correlated (r = 0.44, p < 0.01). Bland-Altman plots for M_TCSA revealed that larger MCSAs related to larger discrepancy between the distal and the mid-leg locations. This is the first study to assess the ability of HR-pQCT to measure M_T size, density, and morphometry. HR-pQCT-derived M_TD was moderately correlated with mid-leg MD from pQCT. This relationship suggests that distal M_T may share common properties with muscle throughout the length of the leg. Future studies will assess the value of HR-pQCT-derived M_T properties in the context of falls, mobility, and balance.

Effect of Metabolic Syndrome on the Mobility Benefit of a Structured Physical Activity Intervention-The Lifestyle Interventions and Independence for Elders Randomized Clinical Trial

OBJECTIVES

To test whether structured physical activity (PA) is associated with a greater reduction in major mobility disability (MMD) in older persons with metabolic syndrome (MetS) than in those without.

DESIGN

Data from the Lifestyle Interventions and Independence for Elders (LIFE) Study, a multicenter randomized trial of 1,635 persons with assessments every 6 months (average 2.7 years).

SETTING

Eight U.S. centers.

PARTICIPANTS

Sedentary men and women aged 70 to 89 with functional limitations (N = 1,535); 100 participants were excluded because of missing MetS data.

INTERVENTION

Participants were randomized to a moderate-intensity PA program (n = 766) or a health education program (n = 769).

MEASUREMENTS

MetS was defined according to the 2009 multiagency harmonized criteria. Outcomes included incident MMD (loss of ability to walk 400 m) and persistent MMD (two consecutive MMD diagnoses or one MMD diagnosis followed by death).

RESULTS

Seven hundred sixty-three (49.7%) participants met criteria for MetS. PA reduced incident MMD more than health education did in participants with MetS (hazard ratio (HR) = 0.72, 95% confidence interval (CI) = 0.57-0.91, P = .007) but not in those without MetS (HR = 0.96, 95% CI = 0.73-1.25, P = .75); the test for statistical interaction was not significant (P = .13). PA reduced the risk of persistent MMD in participants with MetS (HR = 0.57, 95% CI = 0.41-0.79, P < .001) but not in those without MetS (HR = 0.97, 95% CI = 0.67-1.41, P = .87). The test for statistical interaction was significant (P = .04).

CONCLUSION

Moderate-intensity PA substantially reduces the risk of persistent MMD in older persons with functional limitations with MetS but not in those without MetS. Comparable results were observed for incident MMD. The LIFE PA program may be an effective strategy for reducing mobility disability in vulnerable older persons with MetS.

Physical-Performance Outcomes and Biomechanical Correlates from the 32-Week Yoga Empowers Seniors Study

Background. Yoga Empowers Seniors Study (YESS) quantified physical demands associated with yoga performance using biomechanical methods. This study evaluated the efficacy of the program on physical function outcomes. Methods. Twenty community-dwelling older adults aged 70.7 ± 3.8 years attended biweekly 60-minute Hatha yoga classes for 32 weeks. Four domains of the physical measurements including (1) functional performance, (2) flexibility, (3) muscle strength, and (4) balance were taken at the baseline, 16-week and 32-week time points. Repeated-measures ANOVA omnibus tests and Tukey's post hoc tests were employed to examine the differences in each outcome variable across the 3 time points. Results. Improved timed chair stands (p < 0.01), 8-foot up and go (p < 0.05), 2-min step test (p < 0.05), and vertical reach (p = 0.05) performance were evident. Isometric knee flexor strength (p < 0.05) and repetitions of the heel rise test (p < 0.001) also increased following the 32-week intervention. Both flexibility and balance performance remained unchanged. Conclusions. Significant improvements in physical function and muscle-specific lower-extremity strength occur with the regular practice of a modified Hatha yoga program designed for seniors. These adaptations corresponded with the previously reported biomechanical demands of the poses.

Evaluating the relationship between muscle and bone modeling response in older adults

Bone modeling, the process that continually adjusts bone strength in response to prevalent muscle-loading forces throughout an individual's lifespan, may play an important role in bone fragility with age. Femoral stress, an index of bone modeling response, can be estimated using measurements of DXA derived bone geometry and loading information incorporated into an engineering model. Assuming that individuals have adapted to habitual muscle loading forces, greater stresses indicate a diminished response and a weaker bone. The purpose of this paper was to evaluate the associations of lean mass and muscle strength with the femoral stress measure generated from the engineering model and to examine the extent to which lean mass and muscle strength account for variation in femoral stress among 2539 healthy older adults participating in the Health ABC study using linear regression. Mean femoral stress was higher in women (9.51, SD=1.85Mpa) than in men (8.02, SD=1.43Mpa). Percent lean mass explained more of the variation in femoral stress than did knee strength adjusted for body size (R(2)=0.187 vs. 0.055 in men; R(2)=0.237 vs. 0.095 in women). In models adjusted for potential confounders, for every percent increase in lean mass, mean femoral stress was 0.121Mpa lower (95% CI: -0.138, -0.104; p<0.001) in men and 0.139Mpa lower (95% CI: -0.158, -0.121; p<0.001) in women. The inverse association of femoral stress with lean mass and with knee strength did not differ by category of BMI. Results from this study provide insight into bone modeling differences as measured by femoral stress among older men and women and indicate that lean mass may capture elements of bone's response to load.

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.

Combination of body mass-based resistance training and high-intensity walking can improve both muscle size and V˙O2 peak in untrained older women

AIM

Here, we aimed to compare the effect of a combination of body mass-based resistance exercise and moderate-intensity (55% peak oxygen uptake [ V˙O₂ peak]) walking or high-intensity (75% V˙O₂ peak) walking on muscle size and V˙O₂ peak in untrained older women.

METHODS

A total of 12 untrained older women (mean age 60 ± 2 years) were randomly assigned to either a moderate-intensity aerobic training group (n = 6) or high-intensity aerobic training group (n = 6). Both groups carried out body-mass based (lower body) resistance exercises (2 sets of 10 repetitions) on 3 days/week for 8 weeks. Between these exercises, the participants in the moderate-intensity aerobic training group walked at a previously determined speed equivalent to 55% V˙O₂ peak, whereas those in the high-intensity aerobic training group walked at a speed equivalent to 75% V˙O₂ peak.

RESULTS

Muscle thickness of the anterior aspect of the thigh and maximal isokinetic knee extension strength significantly increased in both groups (P < 0.01); these relative changes were negatively correlated with the absolute muscle thickness of the anterior aspect of the thigh value and the relative value of maximal knee strength to body mass at pre-intervention, respectively. A significant group × time interaction was noted for V˙O₂ peak (P < 0.05), which increased only in the high-intensity aerobic training group.

CONCLUSIONS

Body mass-based resistance training significantly induced muscle hypertrophy in untrained older women. In particular, lower muscle thickness before intervention was associated with greater training-induced growth. Furthermore, V˙O₂ peak can be increased by combined circuit training involving low-load resistance exercise and walking, particularly when a relatively high intensity of walking is maintained. Geriatr Gerontol Int 2017; 17: 779-784.

Primary Sarcopenia in Older People with Normal Nutrition

OBJECTIVE

The aim of this study was to investigate the presence of primary sarcopenia in older patients with normal nutrition and to assess the relationships between the primary sarcopenia with anthropometric measurements.

DESIGN AND METHODS

In this prospective clinical cross-sectional study, six-hundred patients who applied to Polyclinic of Geriatrics between dates 2010 and 2011 have been evaluated. The 386 patients who were supposed to have potential secondary sarcopenia were excluded from the study. Age, gender, weight, height, BMI, calf and waist circumference, ongoing medications, additional diseases of the 214 patients included in the study have been surveyed. The sarcopenia criteria of EWSGOP have been applied.

RESULTS

Two hundred fourteen cases included in the study were composed of 148 female and 66 male subjects. Mean age was 71.8 ± 2.1 years. Sarcopenia was detected in 105 (49%) subjects while 109 (51%) were normal. Sixty-four female (61%) and 41 (39%) male subjects were sarcopenic. Normal group included 84 female (77%) and 25 male (23%) subjects. Incidence of sarcopenia was found higher in the female patients (p<0.001). No statistically significant difference was detected between sarcopenic and normal groups with respect to age, height, weight, calf circumference and evaluation tests. Waist circumference was higher in the sarcopenic group than the normal group (p=0.02). When both groups were analyzed for BMI; 53 (51%) of the 105 sarcopenic patients had BMI over 30 kg/m2 while 29 (27%) and 23 (22%) patients had BMI of 25-30 kg/m2 and below 25 kg/m2, respectively. Incidence of sarcopenia was significantly higher in the group with BMI over 30 kg/m2 when compared with the groups with BMI of 25-30 kg/m2 and below 25 kg/m2 (p=0.01).

CONCLUSION

Sarcopenia that makes older people physically dependent and decreases their quality of life that receive sufficient nutritional support and are also obese should be comprehensively investigated with respect to presence of sarcopenia.

Muscle Strength and Changes in Physical Function in Women With Systemic Lupus Erythematosus

OBJECTIVE

Cross-sectional studies have observed that muscle weakness is associated with worse physical function among women with systemic lupus erythematosus (SLE). The present study examines whether reduced upper and lower extremity muscle strength predict declines in function over time among adult women with SLE.

METHODS

One hundred forty-six women from a longitudinal SLE cohort participated in the study. All measures were collected during in-person research visits approximately 2 years apart. Upper extremity muscle strength was assessed by grip strength. Lower extremity muscle strength was assessed by peak knee torque of extension and flexion. Physical function was assessed using the Short Physical Performance Battery (SPPB). Regression analyses modeled associations of baseline upper and lower extremity muscle strength with followup SPPB scores controlling for baseline SPPB, age, SLE duration, SLE disease activity (Systemic Lupus Activity Questionnaire), physical activity level, prednisone use, body composition, and depression. Secondary analyses tested whether associations of baseline muscle strength with followup in SPPB scores differed between intervals of varying baseline muscle strength.

RESULTS

Lower extremity muscle strength strongly predicted changes over 2 years in physical function even when controlling for covariates. The association of reduced lower extremity muscle strength with reduced physical function in the future was greatest among the weakest women.

CONCLUSION

Reduced lower extremity muscle strength predicted clinically significant declines in physical function, especially among the weakest women. Future studies should test whether therapies that promote preservation of lower extremity muscle strength may prevent declines in function among women with SLE.

Does computed tomography-based muscle density predict muscle function and health-related quality of life in patients with idiopathic inflammatory myopathies?

OBJECTIVE

To investigate the association of low-density (lipid-rich) muscle measured by computed tomography (CT) with skeletal muscle function and health-related quality of life in idiopathic inflammatory myopathies (IIMs).

METHODS

Seventeen patients and 10 healthy controls underwent CT of the midthigh to quantify high- (30-100 HU) and low-density (0-29 HU) skeletal muscle areas. Anthropometric measures, body composition, physical activity level, health-related quality of life, skeletal muscle strength, endurance, and fatigue were assessed. Patients were compared against controls. The relationship of anthropometric, body composition, and disease variables with measures of muscle function were examined using Spearman's test on the patient group. Linear regression was used to assess the age- and disease-adjusted relationship of muscle quality to physical function and muscle strength.

RESULTS

Patients had higher body fat percentage (P = 0.042), trunk fat mass (P = 0.042), android:gynoid fat (P = 0.033), and midthigh low-density muscle/total muscle area (P < 0.001) compared to controls. Midthigh low-density muscle/total muscle area was negatively correlated with self-reported physical function, strength, and endurance (the Short Form 36 [SF-36] health survey physical functioning [P = 0.004], manual muscle testing [P = 0.020], knee maximal voluntary isometric contraction/thigh mineral-free lean mass [P < 0.001], and the endurance step test [P < 0.001]), suggesting that muscle quality impacts function in IIM. Using multiple linear regression adjusted for age, global disease damage, and total fat mass, poor muscle quality as measured by midthigh low-density muscle/total muscle area was negatively associated with SF-36 physical functioning (P = 0.009).

CONCLUSION

Midthigh low-density muscle/total muscle area is a good predictor of muscle strength, endurance, and health-related quality of life as it pertains to physical functioning in patients with IIMs.

Effect of whole-body vibration training on body composition, exercise performance and biochemical responses in middle-aged mice

AIMS

Whole-body vibration (WBV) is a well-known light-resistance exercise by automatic adaptations to rapid and repeated oscillations from a vibrating platform, which is also a simple and convenient exercise for older adults. However, the potential benefits of WBV on aging-associated changes in body composition, exercise performance, and fatigue are currently unclear. The objective of the study is to investigate the beneficial effects of WBV training on body composition, exercise performance, and physical fatigue-related and biochemical responses in middle-aged mice.

METHODS

In total, 24 male C57BL/6 mice aged 15 months old were randomly divided into 3 groups (n=8 per group): sedentary control (SC), relatively low-frequency WBV (5.6 Hz, 2 mm, 0.13 g) (LV), and relatively high-frequency WBV (13 Hz, 2 mm, 0.68 g) (HV). Mice in the LV and HV groups were placed inside a vibration platform and vibrated at different frequencies and fixed amplitude (2 mm) for 15 min, 5 days/week for 4 weeks. Exercise performance, core temperature and anti-fatigue function were evaluated by forelimb grip strength and levels of serum lactate, ammonia, glucose, and creatine kinase (CK) after a 15-min swimming exercise, as were changes in body composition and biochemical variables at the end of the experiment.

RESULTS

Relative muscle and brown adipose tissue weight (%) was significantly higher for the HV than SC mice, but relative liver weight (%) was lower. On trend analysis, WBV increased grip strength, aerobic endurance and core temperature in mice. As well, serum lactate, ammonia and CK levels were dose-dependently decreased with vibration frequency after the swimming test. Fasting serum levels of albumin and total protein were increased and serum levels of alkaline phosphatase and creatinine decreased dose-dependently with vibration frequency. Moreover, WBV training improved the age-related abnormal morphology of skeletal muscle, liver and kidney tissues. Therefore, it could improve exercise performance and ameliorate fatigue and prevent senescence-associated biochemical and pathological alterations in middle-aged mice.

CONCLUSIONS

WBV training may be an effective intervention for health promotion in the aging population. The detailed molecular mechanism of how WBV training regulates anti-aging activity warrants further functional studies.

Handgrip strength, ageing and mortality in rural Africa

Background: muscle strength measured as handgrip strength declines with increasing age and predicts mortality. While handgrip strength is determined by lifestyle through nutrition and physical activity, it has almost exclusively been studied in western populations with a sedentary lifestyle. This study aims to investigate the relation between handgrip strength, ageing and mortality in a population characterised by a predominance of malnutrition and manual labour.

Design: a population-based longitudinal study.

Setting: a traditional African rural population in Ghana.

Subjects: nine hundred and twenty-three community-dwelling individuals aged 50 and older.

Methods: demographic characteristics were registered. At baseline, height, body mass index (BMI) and handgrip strength were measured and compared with those in a western reference population. Survival of the participants was documented during a period of up to 2 years.

Results: handgrip strength was dependent on age, sex, height and BMI. Compared with the western reference population, handgrip strength was lower due to a lower height and BMI but declined over age similarly. Risk of mortality was lower in participants having higher handgrip strength, with a hazard ratio of 0.94 per kg increase (P = 0.002). After adjustment for age, sex, tribe, socio-economic status, drinking water source, height and BMI, only handgrip strength remained predictive of mortality.

Conclusion: in a traditional rural African population characterised by malnutrition and manual labour, handgrip strength declines over age and independently predicts mortality similar to western populations. Handgrip strength can be used as a universal marker of ageing.

Muscle strength, muscle mass, and physical disability in women with systemic lupus erythematosus

OBJECTIVE

Data describing relationships between muscle strength, muscle mass, and physical disability among individuals with systemic lupus erythematosus (SLE) are limited. The present study examines the relationship of muscle strength and muscle mass with physical disability among adult women with SLE.

METHODS

A total of 146 women from a longitudinal SLE cohort participated in the study. All measures were collected during an in-person research visit. Lower extremity muscle strength was assessed by peak knee torque of extension and flexion and by chair-stand time. Total lean body mass, appendicular lean mass, and fat mass (kg/m(2) ) were measured by whole-body dual x-ray absorptiometry. Self-reported physical disability was assessed using the Short Form 36 health survey (SF-36) physical functioning subscale, and the Valued Life Activities (VLA) disability scale. Spearman's rank correlation coefficients tested the correlations between muscle strength, muscle mass, and disability scores. Regression analyses modeled the effect of lower extremity muscle strength and mass on SF-36 and VLA disability scores controlling for age, SLE duration, SLE disease activity measured with the Systemic Lupus Activity Questionnaire, physical activity level, prednisone use, body composition, and depression.

RESULTS

On all measures, reduced lower extremity muscle strength was associated with poorer SF-36 and VLA disability scores. Trends persisted after adjustment for covariates. Muscle mass was moderately correlated with muscle strength, but did not contribute significantly to adjusted regression models.

CONCLUSION

Lower extremity muscle strength, but not muscle mass, was strongly associated with physical disability scores. While further studies are needed, these findings suggest that improving muscle strength may reduce physical disability among women with SLE.

Improving reliability of pQCT-derived muscle area and density measures using a watershed algorithm for muscle and fat segmentation

In peripheral quantitative computed tomography scans of the calf muscles, segmentation of muscles from subcutaneous fat is challenged by muscle fat infiltration. Threshold-based edge detection segmentation by manufacturer software fails when muscle boundaries are not smooth. This study compared the test-retest precision error for muscle-fat segmentation using the threshold-based edge detection method vs manual segmentation guided by the watershed algorithm. Three clinical populations were investigated: younger adults, older adults, and adults with spinal cord injury (SCI). The watershed segmentation method yielded lower precision error (1.18%-2.01%) and higher (p<0.001) muscle density values (70.2±9.2 mg/cm3) compared with threshold-based edge detection segmentation (1.77%-4.06% error, 67.4±10.3 mg/cm3). This was particularly true for adults with SCI (precision error improved by 1.56% and 2.64% for muscle area and density, respectively). However, both methods still provided acceptable precision with error well under 5%. Bland-Altman analyses showed that the major discrepancies between the segmentation methods were found mostly among participants with SCI where more muscle fat infiltration was present. When examining a population where fatty infiltration into muscle is expected, the watershed algorithm is recommended for muscle density and area measurement to enable the detection of smaller change effect sizes.

Community-dwelling female fallers have lower muscle density in their lower legs than non-fallers: evidence from the Saskatoon Canadian Multicentre Osteoporosis Study (CaMos) cohort

OBJECTIVES

Our objectives were to determine whether peripheral quantitative computed tomography (pQCT)-derived lower leg muscle density and area, and basic functional mobility differ between community-dwelling older women who do and do not report recent falls.

DESIGN

Matched case-control comparison.

SETTING

Academic biomedical imaging laboratory.

PARTICIPANTS

147 Women, 60 years or older (mean age 74.3 y, SD 7.7) recruited from a longitudinal, population-based cohort representing community-dwelling residents in the area of Saskatoon, Canada.

MEASUREMENTS

A cross-sectional pQCT scan of the non-dominant lower leg was acquired to determine muscle density and area. Basic functional mobility (Timed Up and Go Test [TUG]) and SF36 health status were also measured. Fallers (one or more falls) and non-fallers (no falls) were grouped according to a 12-month retrospective survey and matched on measured covariates.

RESULTS

The muscle density of fallers (n = 35) was a median of 2.1 mg/cm3 lower (P = 0.019, 95% C.I. -3.9 to -0.1) than non-fallers (n = 78) after matching and adjusting for age, body mass index, and SF36 general health scores. Muscle area and TUG did not differ between fallers and non-fallers.

CONCLUSIONS

Muscle density may serve as a physiological marker in the assessment of lower leg muscular health and fall risk in community-dwelling elderly women. These results are limited to our study population who were mostly Caucasian. Prospective studies are required for verification.

Body composition and physical function in women with multiple sclerosis

Persons with multiple sclerosis (MS) have reduced physical activity (PA) and lower-limb physical function and potentially disordered body composition compared with their peers without MS. The aim of this study was to determine whether PA and body composition were differentially associated with lower-limb physical function in persons with MS compared with controls. Females with MS and age- and body mass index-matched female controls (n = 51; average age 48.1 +/- 9.7 yr) were measured for PA with daily step counts, relative fat mass (%Fat), and leg lean mass (LM-LEG) via dual energy X-ray absorptiometry and for lower-limb physical function with objective performance tests. Persons with MS had 12.5% to 53% poorer lower-limb physical function than controls (all p < 0.05). PA, %Fat, and LM-LEG to body mass ratio (LM-LEG/BM) were associated with lower-limb physical function in both persons with MS and controls (all p < 0.05). Based on median splits, higher %Fat, lower LM-LEG/BM, and MS conferred poorer lower-limb physical function (all p < 0.05). PA, %Fat, and LM-LEG/BM were associated with lower-limb physical function, suggesting that body composition, specifically reducing adiposity and increasing lean mass and/or increasing PA levels, may be a potential target for MS interventions.

Physical performance and radiographic and clinical vertebral fractures in older men

In men, the association between poor physical performance and likelihood of incident vertebral fractures is unknown. Using data from the MrOS study (N = 5958), we describe the association between baseline physical performance (walking speed, grip strength, leg power, repeat chair stands, narrow walk [dynamic balance]) and incidence of radiographic and clinical vertebral fractures. At baseline and follow-up an average of 4.6 years later, radiographic vertebral fractures were assessed using semiquantitative (SQ) scoring on lateral thoracic and lumbar radiographs. Logistic regression modeled the association between physical performance and incident radiographic vertebral fractures (change in SQ grade ≥1 from baseline to follow-up). Every 4 months after baseline, participants self-reported fractures; clinical vertebral fractures were confirmed by centralized radiologist review of the baseline study radiograph and community-acquired spine images. Proportional hazards regression modeled the association between physical performance with incident clinical vertebral fractures. Multivariate models were adjusted for age, bone mineral density (BMD, by dual-energy X-ray absorptiometry [DXA]), clinical center, race, smoking, height, weight, history of falls, activity level, and comorbid medical conditions; physical performance was analyzed as quartiles. Of 4332 men with baseline and repeat radiographs, 192 (4.4%) had an incident radiographic vertebral fracture. With the exception of walking speed, poorer performance on repeat chair stands, leg power, narrow walk, and grip strength were each associated in a graded manner with an increased risk of incident radiographic vertebral fracture (p for trend across quartiles <0.001). In addition, men with performance in the worst quartile on three or more exams had an increased risk of radiographic fracture (odds ratio [OR] = 1.81, 95% confidence interval [CI] 1.33-2.45) compared with men with better performance on all exams. Clinical vertebral fracture (n =149 of 5813, 2.6%) was not consistently associated with physical performance. We conclude that poorer physical performance is associated with an increased risk of incident radiographic (but not clinical) vertebral fracture in older men.

Muscle activity, cross-sectional area, and density following passive standing and whole body vibration: A case series

OBJECTIVE

To investigate the effects of intermittent passive standing (PS) and whole body vibration (WBV) on the electromyography (EMG) activity, cross-sectional area, and density of lower extremity muscles in individuals with chronic motor complete spinal cord injury (SCI).

DESIGN

Case series.

METHODS

Seven adult men with chronic (≥2 years), thoracic motor complete (AIS A-B) SCI completed a 40-week course of thrice-weekly intermittent PS-WBV therapy, in a flexed knee posture (160°), for 45 minutes per session at a frequency of 45 Hz and 0.6-0.7 mm displacement using the WAVE(®) Pro Plate, with an integrated EasyStand™ standing frame. EMG was measured in major lower extremity muscles to represent muscle activity during PS-WBV. The cross-sectional area and density of the calf muscles were measured using peripheral quantitative computed tomography at the widest calf cross-section (66% of the tibia length) at pre- and post-intervention. All measured variables were compared between the pre- and post-intervention measurements to assess change after the PS-WBV intervention.

RESULTS

PS-WBV acutely induced EMG activity in lower extremity muscles of SCI subjects. No significant changes in lower extremity EMG activity, muscle cross-sectional area, or density were observed following the 40-week intervention.

CONCLUSIONS

Although acute exposure to PS-WBV can induce electrophysiological activity of lower extremity muscles during PS in men with motor complete SCI, the PS-WBV intervention for 40 weeks was not sufficient to result in enhanced muscle activity, or to increase calf muscle cross-sectional area or density.

Decline in functional capacity is unaffected by diet quality alone or in combination with physical activity among generally healthy older adults with T2D from the NuAge cohort

BACKGROUND

Both diet quality (DQ) and physical activity (PA) have been shown to play a role in the prevention of functional capacity (FC) decline. Because older adults (OA) with T2D are at a higher risk of FC decline compared to their non-diabetic counterparts, our aim was to determine if DQ alone, or combined with PA is associated with FC decline in OA with T2D over a 3-year follow-up in a secondary analysis of the NuAge cohort.

METHODS

In 159 OA with T2D (mean age=75 years), FC change was calculated as the difference in FC scores at T1 and T4 measured by the SMAF (Système de Mesure de l'Autonomie Fonctionnelle). Baseline DQ was calculated from three non-consecutive 24-h dietary recalls collected at T1 using the validated Canadian Healthy Eating Index (C-HEI). PA change was calculated from Physical Activity Scale for the Elderly (PASE) as T4-T1. Associations were evaluated between FC decline and four combinations of variables: C-HEI score < or ≥70 with PASE change < or > median and analyzed by GLM while controlling for covariates.

RESULTS

Neither DQ alone nor DQ combined with PA change were associated with FC decline over follow-up.

CONCLUSIONS

The absence of effect may be explained by characteristics of this healthy sample of OA with T2D who showed relatively good adherence to dietary recommendations (mean C-HEI=70) and were highly functional shown by minimal, clinically non-significant FC decline over 3 years. More research is needed to confirm the role of DQ in preventing FC decline in a larger diabetic sample showing clinically significant FC decline.

Greater Effect of Adiposity Than Physical Activity or Lean Mass on Physical Function in Community-Dwelling Older Adults

Adiposity, lean mass, and physical activity (PA) are known to influence physical function in older adults, although the independent influences are not completely characterized. Older adults (N= 156,Mage = 68.9 ± 6.7 yr, 85 men) were assessed for body composition via dual-energy X-ray absorptiometry, PA by accelerometer, and physical function via timed up-and-go (UP&GO), 30-s chair stand, 6-min walk (6-min WALK), and Star-Excursion Balance Test. In the absence of percentage-body-fat by PA interactions (p> .05), main effects existed such that a higher percentage body fat was associated with poorer performance in UP&GO, 30-s chair stand, and 6-min WALK (p< .05). No significant main effects were found for PA and functional performance. Adiposity explains 4.6–11.4% in physical functional variance (p< .05). Preventing increases in adiposity with age may help older adults maintain functional independence.

Peripheral nerve function and lower extremity muscle power in older men

OBJECTIVE

To assess whether sensorimotor peripheral nerve function is associated with muscle power in community-dwelling older men.

DESIGN

Longitudinal cohort study with 2.3±0.3 years of follow-up.

SETTING

One clinical site.

PARTICIPANTS

Participants (n=372; mean age ± SD, 77.2±5.1y; 99.5% white; body mass index, 27.9±3.7kg/m(2); power, 1.88±0.6W/kg) at 1 site of the Osteoporotic Fractures in Men Study (N=5994).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

A nerve function ancillary study was performed 4.6±0.4 years after baseline. Muscle power was measured using a power rig. Peroneal motor nerve conduction amplitude, distal motor latency, and mean f-wave latency were measured. Sensory nerve function was assessed using 10-g and 1.4-g monofilaments and sural sensory nerve conduction amplitude and distal latency. Peripheral neuropathy symptoms at the leg and feet were assessed by self-report.

RESULTS

After adjustments for age, height, and total body lean and fat mass, 1 SD lower motor (β=-.07, P<.05) and sensory amplitude (β=-.09, P<.05) and 1.4-g (β=-.11, P<.05) and 10-g monofilament insensitivity (β=-.17, P<.05) were associated with lower muscle power/kg. Compared with the effect of age on muscle power (β per year, -.05; P<.001), this was equivalent to aging 1.4 years for motor amplitude, 1.8 years for sensory amplitude, 2.2 years for 1.4-g monofilament detection, and 3.4 years for 10-g detection. Baseline 1.4-g monofilament detection predicted a greater decline in muscle power/kg. Short-term change in nerve function was not associated with concurrent short-term change in muscle power/kg.

CONCLUSIONS

Worse sensory and motor nerve function were associated with lower muscle power/kg and are likely important for impaired muscle function in older men. Monofilament sensitivity was associated with a greater decline in muscle power/kg, and screening may identify an early risk for muscle function decline in late life, which has implications for disability.

Interrelated factors favoring physical performance and activity in older adults from the NuAge cohort study

OBJECTIVES

Contribute evidence towards the complex interrelationships of body composition, physical performance and physical activity (PA) in an older population to assist in decisions for maintaining functional capacity in older adults.

DESIGN

This is a cross-sectional analysis of an existing dataset in which a literature-supported model linking together the variables of interest is tested using path analysis. A proposed model with age, sex, energy intake and chronic diseases as predictors associated with body composition components, while the latter associated with physical performance and with PA acting both as a predictor and as an outcome of physical performance.

PARTICIPANTS

A sample of 847, community dwellers, non-diabetic older men and women from the Quebec Longitudinal Study on Nutrition and Successful Aging (NuAge Study).

MEASUREMENTS

Physical performance tests were reduced to two indices: strength and mobility. Muscle mass index (MMI; kg/height(2)) and % body fat were derived from DXA and bioimpedance analysis (BIA). PA was assessed by the Physical Activity Scale for the Elderly (PASE) and energy intakes were calculated from 24-hour food recalls. Data from the NuAge dataset served to test the relationships. The proposed model was evaluated using indices of fit.

RESULTS

Significant associations were found for MMI and % body fat with mobility (β -0.11 and -0.02, respectively), and for MMI with strength (β=0.60). PA was associated with MMI (β=0.02) and negatively with % body fat (β=-0.16), while mobility associated with PA (β=0.65). Our hypothesized model, with some paths added, fit the data: chi-square=4.64, root mean square error of approximation (RMSEA)=0.

CONCLUSIONS

PA has desirable associations with body composition in older adults and mobility is associated with PA. These results stress the importance of taking into account the prior level of mobility when recommending PA for this age group. This model could explain in part the complex interrelationships that occur with aging and the potential factors that could be targeted to assist older individuals in maintaining functional capacity.

Vitamin D deficiency and its role in muscle-bone interactions in the elderly

In this commentary, we focus on common 'downstream' links of vitamin D between muscle and bone health. Both direct and indirect effects of 1,25 dihydroxyvitamin D (1,25(OH)D) link the mutual age-related decline in muscle function and bone density, independent of physical activity. Changes in calcium absorption associated with vitamin D deficiency affect both muscle and bone mass. The age-related decline in vitamin D receptor expression and 1,25(OH)D activity impact on proinflammatory cytokines such as tumor necrosis factor -α and interleukin-6 in skeletal muscle and vitamin D deficiency appears to enhance both bone marrow adipogenesis and intramuscular adipose tissue impacting as reduced functionality in both skeletal tissues. Controversial findings on the role of 1,25(OH)D on skeletal muscle may relate to differences in vitamin D receptor expression throughout different stages of muscle cell differentiation. Prolonged vitamin D insufficiency in the elderly is associated with reductions in both bone mineral density and type 2 muscle fibers with the outcomes of skeletal fragility in combination with reduced muscle power, leading to increased risk of falls and fracture.

Clinical implications of body composition assessment by computed tomography in metastatic renal cell carcinoma

According to computed tomography image analysis, skeletal muscle (SM) and adipose tissue areas vary widely in patients with the same body mass index or the same body surface area. Body composition variables such as SM mass, SM density and subcutaneous and visceral adipose tissue have shown value as potential independent predictive factors for survival in cancer patients, although data for patients with renal cell carcinoma (RCC) undergoing targeted therapy remain relatively scarce. Confirmation of their prognostic value is required before they can be considered useful adjuncts to conventional predictive models of survival in RCC patients. In addition, variability in SM mass might affect drug toxicity, with patients with a low rather than high SM mass being at a higher risk of toxicity. A dose tailored to the individual patient's SM mass might lower toxicity in RCC patients, enable completion of the treatment plan and thus impact favorably on treatment effectiveness.