Muscle quality as a complementary prognostic tool in conjunction with sarcopenia assessment in younger and older individuals

Can EWGSOP2 and SDOC Definitions of Sarcopenia Identify Functional Muscle Quality?

Objectives

To compare the European Working Group on Sarcopenia in Older People (EWGSOP2) and the Sarcopenia Definition and Outcomes Consortium (SDOC) in identifying muscle quality indexes (MQI) and lower limb muscle performance in older women aged ≥ 65.

Methods

Participants meeting EWGSOP2 and SDOC criteria were classified into the sarcopenia group (GS); others were placed in the non-sarcopenia group (GNS). Using an isokinetic dynamometer, we assessed peak torque (PT), maximal work (MW), and power (POW) of lower limbs. MQI was calculated as the ratio of muscle performance to appendicular lean mass, adjusted for body mass index (BMI) and lean tissue mass of the right lower limb (LTM).

Results

We included 96 older women. In both SDOC (n=37) and EWGSOP2 (n=48) sarcopenia groups, muscle performance and BMI-adjusted MQI were significantly lower. Sarcopenia (SDOC) was significantly associated with all lower limb muscle performance and MQI variables [adjusted model by age and race: MQIPOW/LTM OR = 0.67 (95% CI 0.52; 0.85); MQIPT/LTM OR = 0.76 (95% CI 0.64; 0.89)].

Conclusions

Older women diagnosed with sarcopenia by EWGSOP2 and SDOC criteria showed significant declines in muscle function and quality. The SDOC definition discriminated muscle contraction quality components in older individuals with and without sarcopenia.

Addressing cancer anorexia-cachexia in older patients: Potential therapeutic strategies and molecular pathways

Cancer cachexia (CC) syndrome, a feature of cancer-associated muscle wasting, is particularly pronounced in older patients, and is characterised by decreased energy intake and upregulated skeletal muscle catabolic pathways. To address CC, appetite stimulants, anabolic drugs, cytokine mediators, essential amino acid supplementation, nutritional counselling, cognitive behavioural therapy, and enteral nutrition have been utilised. However, pharmacological treatments that have also shown promising results, such as megestrol acetate, anamorelin, thalidomide, and delta-9-tetrahydrocannabinol, have been associated with gastrointestinal and cardiovascular complications. Emerging evidence on the efficacy of probiotics in modulating gut microbiota also presents a promising adjunct to traditional therapies, potentially enhancing nutritional absorption and systemic inflammation control. Additionally, low-dose olanzapine has demonstrated improved appetite and weight management in older patients undergoing chemotherapy, offering a potential refinement to current therapeutic approaches. This review aims to elucidate the molecular mechanisms underpinning CC, with a particular focus on the role of anorexia in exacerbating muscle wasting, and to propose pharmacological and non-pharmacological strategies to mitigate this syndrome, particularly emphasising the needs of an older demographic. Future research targeting CC should focus on refining appetite-stimulating drugs with fewer side-effects, specifically catering to the needs of older patients, and investigating nutritional factors that can either enhance appetite or minimise suppression of appetite in individuals with CC, especially within this vulnerable group.

Improved Physical Health in Middle-Older Aged Golf Caddies Following 24 Weeks of High-Volume Physical Activity

BACKGROUND

The physical demands of golf caddying, including walking while carrying a golf bag, may potentially affect body composition, and markers of metabolic, cardiovascular, and musculoskeletal health. Therefore, this study examined the impact of 24 weeks of caddying on physical health in middle-older aged males.

METHODS

Eleven full-time experienced male caddies (age: 59 [8] y; caddying experience: 14 [12] y) were recruited from a local golf course. The following were assessed at preseason and after 24 weeks of caddying (March-September 2022): body composition, heart rate, blood pressure, blood lipids, and performance tests (static and dynamic balance, strength, and submaximal fitness). Physical activity (PA) levels were assessed at preseason and at the mid-point of the caddying season. Across the caddying season, participants completed a monthly average of 24.0 (3.8) rounds.

RESULTS

Following the caddying season, improvements in static balance (Δ = 13.5 s), dynamic balance (Δ = -1.8 s), and lower back absolute strength (Δ = 112.8 N), and muscle quality (Δ = 2.0 N·kg-1) were observed (all P < .05). Additionally, blood lipids, including total cholesterol (Δ = -0.6 mmol·L-1), high-density lipoprotein cholesterol (Δ = 0.1 mmol·L-1), low-density lipoprotein cholesterol (Δ = -0.6 mmol·L-1) (all P < .05), and body composition, including body mass (Δ = -2.7 kg), fat mass (Δ = -1.9 kg), fat percentage (Δ = -1.4%), fat-to-muscle ratio (Δ = -0.03), and body mass index (Δ = -0.9 kg·m-2) (all P < .05) improved. Caddying did not offer beneficial changes to cardiovascular variables or cardiorespiratory fitness (P > .05), while coronary heart disease risk score decreased (Δ = -3.3%) (P < .05). In relation to PA, light- (Δ = 145 min) and moderate-intensity (Δ = 71 min) PA, moderate to vigorous PA (Δ = 73 min), and total PA (Δ = 218 min) between preseason and the mid-point of the caddying season increased, while sedentary time (Δ = -172 min) decreased (all P < .05).

CONCLUSION

Golf caddying can provide several physical health benefits such as improvements in various markers of cardiometabolic health, lower back absolute strength, and static and dynamic balance. The physical health improvements that caddying offers is likely contributed to by increased PA volume and intensity through walking on the golf course. Therefore, caddying may represent a feasible model for increasing PA volume and intensity and achieve physical health-related benefits.

Association of Muscle Fat Content and Muscle Mass With Impaired Lung Function in Young Adults With Obesity: Evaluation With MRI

RATIONALE AND OBJECTIVES

Although low muscle mass is associated with decreased lung function, studies exploring the relationship between muscle fat content and lung function impairment are scarce. This study aimed to evaluate the association of muscle mass and fatty infiltration with lung function in young adults with obesity.

MATERIALS AND METHODS

We performed a retrospective cross-sectional study of patients aged 18-45 years with obesity who had impaired pulmonary function (case group, n = 66) and those with normal pulmonary function (control group, n = 198) by matching age, sex, body mass index (BMI), and height to assess whether muscle characteristics differed. Muscle mass and muscle fat content were assessed by MRI using a chemical shift-encoded sequence (IDEAL-IQ).

RESULTS

A total of 264 patients were enrolled (124 females; mean age 32.0 years). The case group had lower muscle mass than the control group (p = 0.012), and there was an association between low muscle mass and lung function impairment (odds ratio (OR), 3.74; 95% confidence interval (CI), 1.57-8.93). Furthermore, muscle fat content was significantly higher in cases compared to controls (7.4 (2.7) % vs. 6.2 (2.5) %, p = 0.001). Multiple logistic regression analysis showed that muscle fat content was associated with a higher risk of impaired lung function (OR, 2.10; 95% CI, 1.65-2.66), regardless of adiposity and muscle mass.

CONCLUSION

Both muscle fat content and muscle mass are associated with impaired lung function in young adults with obesity.

A machine learning approach to identify important variables for distinguishing between fallers and non-fallers in older women

Falls are a significant ongoing public health concern for older adults. At present, few studies have concurrently explored the influence of multiple measures when seeking to determine which variables are most predictive of fall risks. As such, this cross-sectional study aimed to identify those functional variables (i.e. balance, gait and clinical measures) and physical characteristics (i.e. strength and body composition) that could best distinguish between older female fallers and non-fallers, using a machine learning approach. Overall, 60 community-dwelling older women (≥65 years), retrospectively classified as fallers (n = 21) or non-fallers (n = 39), attended three data collection sessions. Data (281 variables) collected from tests in five separate domains (balance, gait, clinical measures, strength and body composition) were analysed using random forest (RF) and leave-one-variable-out partial least squares correlation analysis (LOVO PLSCA) to assess variable importance. The strongest discriminators from each domain were then aggregated into a multi-domain dataset, and RF, LOVO PLSCA, and logistic regression models were constructed to identify the important variables in distinguishing between fallers and non-fallers. These models were used to classify participants as either fallers or non-fallers, with their performance evaluated using receiver operating characteristic (ROC) analysis. The study found that it is possible to classify fallers and non-fallers with a high degree of accuracy (e.g. logistic regression: sensitivity = 90%; specificity = 87%; AUC = 0.92; leave-one-out cross-validation accuracy = 63%) using a combination of 18 variables from four domains, with the gait and strength domains being particularly informative for screening programmes aimed at assessing falls risk.

Frailty but not low muscle quality nor sarcopenia is independently associated with mortality among previously hospitalized older adults: A prospective study

AIM

There are few studies comparing the effects of geriatric syndromes and abnormalities in nutritional status and body composition on outcomes among older individuals who have been previously hospitalized. Our study aimed to evaluate the frequency and diagnosis of geriatric syndromes, low muscle quality, and nutritional status in hospitalized older individuals, and to examine their impact on both short- and long-term outcomes.

METHODS

This was a prospective study involving older adults (≥60 years). We assessed nutritional status, muscle quality, sarcopenia, and frailty. The outcomes were functional dependence, length of hospital stay, transfer to the Intensive Care Unit, number of readmissions, and mortality. Multivariate analysis was conducted to identify independent risk factors.

RESULTS

Even after adjustment for age and sex, increased risk of death was associated with possible undernourishment, sarcopenia, low muscle quality, and frailty (P < 0.05), but not the length of hospital stay (P > 0.05). Our multivariate analysis showed that frailty was independently associated with mortality and functional dependence. Low muscle quality was independently associated with functional dependence.

CONCLUSIONS

Geriatric syndromes, abnormalities in body composition, and the overall nutritional status of older patients are important risk factors for adverse outcomes, including functional dependence and mortality. These findings emphasize the need for interventions to improve muscle quality, prevent and treat malnutrition and sarcopenia, and address frailty in hospitalized patients. Geriatr Gerontol Int 2023; 23: 736-743.

Muscle performance in octogenarians: Factors affecting dynapenia

BACKGROUND

The muscle performance is associated with several health outcomes in adults, however modifiable and non-modifiable risk factors in octogenarians have not yet been fully investigated. The aim of this study was to analyze the potential risk factors that negatively affect muscle strength in octogenarians.

METHODS

This observational, descriptive, cross-sectional study included 87 older adult participants (56 women and 31 men) attending a geriatric clinic. General anthropometrics, health history, and body composition data were collected. Muscle strength was assessed by handgrip strength (HGS), appendicular skeletal muscle mass (ASMM) and the percentage of body fat were identified by Dual Energy X-ray Absorptiometry, and muscle quality index (MQI) was defined as the ratio of HGS by upper limbs ASMM. Multiple linear regression was conducted to determine predictive factors of the muscle strength.

RESULTS

Females had lower HGS (1.39 kg) than male participants (p = 0.034). An increase of one unit MQI was associated with an increase of 3.38 kg in the HGS (p = 0.001). Each additional year of age was associated with a decrease of 0.12 kg in the HGS (p = 0.047). Regarding ASMM, an increase of one unit was associated with an increase of 0.98 kg in the HGS (p = 0.001). There was no association between dynapenia, body fat percentage, diseases and polypharmacy (p > 0.05).

CONCLUSION

The gender, age, MQI, and ASMM influenced muscle strength of octogenarians. These intrinsic and extrinsic factors are relevant to improve our understanding of age-related complications and outline treatment guidance by healthcare professionals.

Exploring the impact of exercise and essential amino acid plus cholecalciferol supplementation on physical fitness and body composition in multiple sclerosis: A case study

Key Clinical Message

In MS patients, especially those frail or malnourished, combining home-based exercise twice weekly with essential amino acids and vitamin D may improve body composition, strength, and physical performance, enabling long-term functional improvements.

Abstract

Multiple sclerosis (MS) is associated with reduced bone and muscle strength and function. We aimed to investigate the effectiveness of a 24-week intervention in a 57-year-old frail female with MS. The participant completed a 2×/week exercise intervention and ingested 2×/day a supplement containing 7.5 g essential amino acids and 500 IU cholecalciferol. Body composition, 6-m gait speed (GS), handgrip strength (HGS), 30-sec arm-curl test (30ACT), 6-min walking test (6MWT), 30-sec chair-stand test (30CST), and plasma concentrations of 25-hydroxyvitamin D₃ [25(OH)D₃], insulin-like growth factor 1 (IGF-1), and amino acids were assessed at baseline, and at Weeks 12 and 24. Plasma 25(OH)D₃ increased from 23.2 to 41.3 ng/mL and IGF-1 from 131.6 to 140.7 ng/mL from baseline to post-intervention. BMI, total lean tissue mass (LTM), fat mass, bone mineral content, and the sum of 17 amino acids increased by 3.8, 1.0, 3.5, 0.2, and 19%, respectively, at Week 24. There were clinically significant increases in regional LTM (6.9% arms and 6.3% legs) and large increases in GS (67.3%), dominant HGS (31.5%), non-dominant HGS (11.8%), dominant 30ACT (100%), non-dominant 30ACT (116.7%), 6MWT (125.6%), and 30CST (44.4%). The current intervention was effective in improving components of physical fitness and body composition in a female with MS.

Effects of muscle mass and muscle quality estimated by phase angle on functional outcomes in older patients undergoing rehabilitation: A prospective cohort study

BACKGROUND

Both skeletal muscle mass and muscle quality are important predictors of poor prognosis in older patients. However, the effects of muscle mass and muscle quality estimated by the phase angle (PhA) on functional outcomes in older patients undergoing rehabilitation have yet to be reported. This study aimed to investigate whether appendicular skeletal muscle index (SMI) and muscle quality estimated by PhA were independently associated with activities of daily living (ADL) and physical function in older patients undergoing rehabilitation.

METHODS

This prospective cohort study included older patients in a subacute rehabilitation hospital (n = 443). Baseline SMI and PhA were measured using bioelectrical impedance analysis, and low SMI or low PhA were determined using each cutoff value. The primary outcomes were ADL abilities measured using the functional independence measure for motor function (FIM-M) score and physical function measured using the short physical performance battery (SPPB) score at hospital discharge. Association between low SMI and low PhA and FIM-M or SPPB scores at discharge were determined using multiple regression analysis adjusted for confounding factors.

RESULTS

There were significant differences between the normal- and low-PhA groups in the FIM-M and SPPB scores at discharge (P < 0.001). In multiple regression analysis, low PhA was independently associated with FIM-M (β = -0.109, P = 0.013) and SPPB scores (β = 0.535, P < 0.001) at discharge; however, low SMI was not independently associated with these functional outcomes.

CONCLUSION

Decreased muscle quality estimated by the PhA was independently associated with poor ADL abilities and poor physical function in older patients undergoing rehabilitation.

Adiponectin receptors activation performs dual effects on regulating myogenesis and adipogenesis of young and aged muscle satellite cells

OBJECTIVES

Skeletal muscle mass and function deteriorate with ageing. Adiponectin receptors (APNrs), mainly activated by adiponectin, participate in various physiological activities and have varying signalling pathways at different ages. This study aimed to explore whether discrepant performance exists in APNr activation regulating young and aged muscle satellite cells (MUSCs) and whether age-related muscle dysfunction could be alleviated upon APNr activation.

METHODS

The gastrocnemius muscle phenotype was observed in male mice aged 2 and 18 months. An APNr agonist (AdipoRon) was used in vitro and in vivo to investigate the changes in cell biological behaviours and whether muscle dysfunction could be retarded after APNr activation.

RESULTS

Aged mice exhibited decreased muscle mass and increased fat infiltration. APNr activation inhibited C2C12 cells and young MUSCs (YMUSCs) proliferation but showed no obvious effect on aged MUSCs (AMUSCs). Moreover, APNr activation inhibited the migration of both YMUSCs and AMUSCs. Interestingly, APNr activation hampered the myogenic differentiation but advanced the adipogenic differentiation of YMUSCs, yet exact opposite results were presented in AMUSCs. It was demonstrated that Wnt and PI3K signalling pathways may mediate the phenotypic differences. Furthermore, in vivo experiments verified that APNr activation ameliorated age-related muscle atrophy and excessive fat infiltration.

CONCLUSIONS

APNr activation exerted dual effects on the regulation of myogenesis and adipogenesis of YMUSCs and AMUSCs and rescued age-related skeletal muscle dysfunction.

Esports players, got muscle? Competitive video game players' physical activity, body fat, bone mineral content, and muscle mass in comparison to matched controls

BACKGROUND

Esports players, like traditional athletes, practice for long hours and, thus, are vulnerable to the negative health effects of prolonged sitting. There is a lack of research on the physical activity and the health ramifications of prolonged sitting by competitive players. The purpose of this study was to investigate activity levels, body mass index (BMI), and body composition in collegiate esports players as compared to age-matched controls.

METHODS

Twenty-four male collegiate esports players and non-esports players between 18 and 25 years of age signed a written consent to participate. Physical activity was examined using daily activity (step count) with a wrist-worn activity tracker. A questionnaire assessing physical activity was also administered. Secondary outcomes included body-fat percentage, lean-body mass, BMI, and bone mineral content measured using dual X-ray absorptiometry.

RESULTS

The step count in the esports players was significantly lower than the age-matched controls (6040.2 ± 3028.6 vs. 12843.8 ± 5661.1; p = 0.004). Esports players exhibited greater body-fat percentage (p = 0.05), less lean body mass (p = 0.003), and less bone mineral content (p = 0.03), despite no difference in BMI between the esports and non-esports players.

CONCLUSION

As compared to non-esports players, collegiate esports players were significantly less active and had a higher body-fat percentage, with lower lean body mass and bone mineral content. The BMIs showed no difference between the 2 groups. Esports athletes displayed significantly less activity and poor body composition, which are all correlated with potential health issues and risk of injury. BMI did not capture this difference and should not be considered as an accurate measure of health in competitive esports players.

Muscle Quality and Functional and Conventional Ratios of Trunk Strength in Young Healthy Subjects: A Pilot Study

BACKGROUND

The trunk strength conventional ratio (CR) has been evaluated. However, the functional ratio and the ratio of strength to body weight (BW) or muscle mass (MM) have been poorly explored. Relative strength is a measure of muscle quality.

OBJECTIVES

To analyze the trunk strength ratio normalized by BW and MM and compare the trunk's conventional and functional ratios collected in isokinetic and isometric conditions.

METHODS

Twenty-seven healthy males (21.48 ± 2.08 years, 70.22 ± 7.65 kg) were evaluated for trunk isometric and isokinetic strength using a functional electromechanical dynamometer.

RESULTS

The extensor's strength was greater than the flexors, with a CR of 0.41 ± 0.10 to 0.44 ± 0.10. Muscle quality was higher in eccentric contraction and high velocity for flexors and extensors. The functional flexor ratio (FFR) ranged between 0.41 ± 0.09 and 0.92 ± 0.27. The functional extensor ratio (FER) ranged between 2.53 ± 0.65 and 4.92 ± 1.26. The FFR and FER showed significant differences between velocities when considering the peak strength (p = 0.001) and mean strength (p = 0.001).

CONCLUSIONS

Trunk extensors were stronger than the flexors; thus, the CR was less than one. Muscle quality was higher at a high velocity. Unlike CR, FFR and FER behaved differently at distinct velocities. This finding highlights the need to explore the behavior of the functional ratio in different populations.

Lean Mass, Muscle Strength, and Muscle Quality in Retired Rugby Players: The UK Rugby Health Project

Although athletes from sports such as rugby have greater lean mass and strength during their playing careers, little is known about these characteristics post-retirement. Therefore, this study investigated lean mass, strength, and muscle quality in retired elite and amateur rugby players and non-contact athletes. Retired elite male rugby players (n=42, 43.9±10.3 y; 101.1±13.4 kg; 1.82±0.09 m), amateur rugby players (n=46, 48.0±10.5 y; 98.9±16.6 kg; 1.79±0.07 m) and non-contact athletes (n=30, 51.3±12.5 y; 91.3±13.4 kg; 1.79±0.07 m) received one total body dual-energy X-ray absorptiometry assessment of appendicular lean mass (ALM) and ALM index (ALMI). Grip strength was measured, and muscle quality (grip strength/unit of arm lean mass) was calculated. Sarcopenia was identified as ALMI<7.23 kg/m² and handgrip strength<37.2 kg. Total lean mass, ALM and grip strength were greater in the elite rugby compared to amateur rugby and non-contact groups (p<0.01). There were no significant differences in muscle quality or sarcopenia prevalence. Retired elite rugby players had greater lean mass and grip strength than amateur rugby and non-contact athletes, although muscle quality was similar. The greater lean mass and strength might reflect genetic influences or previous participation in a highly physical sport.

Muscle fat infiltration but not muscle cross-sectional area is independently associated with bone mineral density at the lumbar spine

OBJECTIVE

Although sarcopenia and osteoporosis are inter-related conditions that are common with advancing age, few studies have explored relationships between muscle quality and bone mineral density (BMD). We investigated age- and sex-specific paraspinal muscle fat infiltration (MFI), muscle cross-sectional area (CSA), and spine volumetric BMD (vBMD) in healthy Chinese adults.

METHODS

605 healthy adults aged 20-59 years (340 women, mean age 39.2 years; 265 men, mean age 38.8 years) had axial T2WI MRI imaging of the lumbar spine and CSA (cm2) and MFI (%) were measured in the psoas and multifidus and erector spinae (MF-ES) muscles (L3-L4). MFI measurements were calibrated against a region of interest in an adjacent area of subcutaneous pure fat. L2-L4 vBMD was measured by quantitative CT. Age- and sex-specific subgroups were compared using the Mann-Whitney test. Multiple regression was used to test independent associations of MFI and CSA with vBMD.

RESULTS

Females had lower CSA and higher MFI than males in both the psoas and MF-ES muscles (p < 0.001). In females and males, MF-ES MFI increased with age (p < 0.001) and in females age-related increases were observed for the psoas muscles (p < 0.05). Greater fat infiltration of the MS-ES muscle unit was associated with lower vBMD in both sexes (p < 0.001) but not with CSA. Following adjustment for demographic variables and CSA, MS-ES MFI remained predictive of vBMD (β = -0.408 to -0.157, p < 0.001).

CONCLUSION

We have demonstrated that, independent of CSA and demographic variables, MFI of the MF-ES muscles is predictive of lower lumbar spine vBMD in both sexes.

ADVANCES IN KNOWLEDGE

This is the first study to demonstrate that, independent of muscle size and demographic variables, MFI of the paraspinal MF-ES muscles is predictive of lower lumbar spine vBMD in both sexes.

A combined index of waist circumference and muscle quality is associated with cardiovascular disease risk factor accumulation in Japanese obese patients: a cross-sectional study

PURPOSE

To identify obese patients at high risk of cardiovascular disease (CVD) using a combined index of obesity and sarcopenia.

METHODS

In this cross-sectional study, we firstly conducted analysis of covariance to select each index most associated with the CVD risk score, the number of concomitant CVD risk factors, among obesity- (body mass index, percentage body fat, or waist circumference [WC]) and sarcopenia-evaluated indices (skeletal muscle mass index, handgrip strength, or muscle quality [MQ]), respectively in 188 Japanese obese patients (BMI ≥ 25 kg/m², 73 men and 115 women). Next, we conducted multivariate logistic regression analysis to compare the four groups (Group A-D) classified by medians of the selected indices.

RESULTS

WC and MQ were selected as the indices most associated with the CVD risk scores, respectively. The CVD risk score was significantly higher in Group B (low WC and low MQ) and Group D (high WC and low MQ) with higher prevalence of diabetes as compared with Group A (low WC and high MQ). Adjusted for sex and age, odds ratios for CVD risk scores = 2 were significantly higher in Group B, Group C (high WC and high MQ), and Group D compared with Group A. Furthermore, odds ratios for CVD risk scores = 3 were significantly higher only in Group D compared with Group A (4.29 [95% confidence interval: 1.49-12.33], p = 0.007).

CONCLUSION

Combined index of WC and MQ was useful in Japanese obese patients at high risk of CVD, regardless sex and age.

Associations Between Muscle Quality and Cognitive Function in Older Men: Cross-Sectional Data From the Geelong Osteoporosis Study

Sarcopenia-related declines appear to be adversely associated with cognition in the elderly. Poor muscle quality is a marker for sarcopenia, yet little research has examined the concurrence of poor muscle quality and poor cognition. The aim of this study was to investigate the association between muscle quality and cognitive function, overall and in specific domains, in older men. This study involved 342 men from the Geelong Osteoporosis Study (ages 60-96 years). Handgrip strength (HGS, kg) was measured by dynamometry (Vernier, LoggerPro3), and lean mass of arms (kg) and appendicular lean mass (ALM, kg) by dual-energy X-ray absorptiometry (Lunar). Muscle quality was expressed as HGS/(arm lean mass) (kg/kg) as well as HGS/ALM (kg/kg). Cognitive function was assessed in 4 domains: visual attention, psychomotor function, working memory and visual learning. Overall cognitive function scores were calculated. Higher scores represent poorer cognitive performance in attention, psychomotor function and working memory, but better performance for visual memory/learning and overall cognitive function. Additionally, cognitive impairment was determined by the mini-mental state exam (score ≤ 24). Linear regression analyses and logistic regression were performed. There were age-related declines observed for all measures relating to muscle and cognition. Muscle quality (HGS/arm lean mass) was associated with all cognition assessments before and after adjusting for age, except for age-adjusted working memory. Muscle quality (HGS/arm lean mass) was associated with psychomotor function (B -0.01, 95% CI -0.02, -0.005) and overall cognitive function (b + 0.07, 95% CI 0.03, 0.11) after adjusting for age and education. Greater muscle quality was also associated with the likelihood of cognitive impairment OR 0.64 (95%CI 0.46-0.88) after adjusting for age; associations with attention and visual memory/learning were attenuated after further adjustment for confounders. Similar patterns were observed when muscle quality was determined as HGS/ALM. Our data support an association between muscle quality and cognitive function. Further research is needed to examine temporal changes between the Two.

Adiponectin receptor agonist AdipoRon improves skeletal muscle function in aged mice

The loss of skeletal muscle function with age, known as sarcopenia, significantly reduces independence and quality of life and can have significant metabolic consequences. Although exercise is effective in treating sarcopenia it is not always a viable option clinically, and currently, there are no pharmacological therapeutic interventions for sarcopenia. Here, we show that chronic treatment with pan-adiponectin receptor agonist AdipoRon improved muscle function in male mice by a mechanism linked to skeletal muscle metabolism and tissue remodeling. In aged mice, 6 weeks of AdipoRon treatment improved skeletal muscle functional measures in vivo and ex vivo. Improvements were linked to changes in fiber type, including an enrichment of oxidative fibers, and an increase in mitochondrial activity. In young mice, 6 weeks of AdipoRon treatment improved contractile force and activated the energy-sensing kinase AMPK and the mitochondrial regulator PGC-1a (peroxisome proliferator-activated receptor gamma coactivator one alpha). In cultured cells, the AdipoRon induced stimulation of AMPK and PGC-1a was associated with increased mitochondrial membrane potential, reorganization of mitochondrial architecture, increased respiration, and increased ATP production. Furthermore, the ability of AdipoRon to stimulate AMPK and PGC1a was conserved in nonhuman primate cultured cells. These data show that AdipoRon is an effective agent for the prevention of sarcopenia in mice and indicate that its effects translate to primates, suggesting it may also be a suitable therapeutic for sarcopenia in clinical application.

Phase angle from bioelectrical impedance analysis is a useful indicator of muscle quality

BACKGROUND

Methods that facilitate muscle quality measurement may improve the diagnosis of sarcopenia. Current research has focused on the phase angle (PhA) obtained through bioelectrical impedance analysis (BIA) as an indicator of cellular health, particularly cell membrane integrity and cell function. The current study therefore aimed to evaluate the relationship between the PhA and muscle quality and muscle-related parameters and to determine factors associated with the PhA. Moreover, we attempted to determine the cut-off value of PhA for predicting sarcopenia.

METHODS

First-year university students (830 male students, 18.5 ± 0.6 years old; 422 female students, 18.3 ± 0.5 years old) and community-dwelling elderly individuals (70 male individuals, 74.4 ± 5.5 years old; 97 female individuals, 73.1 ± 6.4 years old) were included. PhA and other body composition data were measured using BIA, while muscle quality was calculated by dividing handgrip strength by upper limbs muscle mass. The relationship between PhA and the aforementioned parameters were then analysed, after which the cut-off value of PhA for predicting sarcopenia was examined.

RESULTS

Multiple linear regression analysis revealed that age, skeletal muscle mass index (SMI), and muscle quality were independently associated with PhA in both sexes [male (age: standardized regression coefficient (β) = -0.43, P < 0.001, SMI: β = 0.61, P < 0.001, muscle quality: β = 0.13, P < 0.001) and female (age: β = -0.56, P < 0.001, SMI: β = 0.52, P < 0.001, muscle quality: β = 0.09, P = 0.007)]. Participants with sarcopenia had a significantly lower PhA compared with those without it (sarcopenia vs. non-sarcopenia: young male participants, 5.51 ± 0.41° vs. 6.25 ± 0.50°, P < 0.001; young female participants, 4.88 ± 0.16° vs. 5.37 ± 0.44°, P = 0.005; elderly female participants: 4.14 ± 0.29° vs. 4.63 ± 0.42°, P = 0.009). Although no significant findings were observed in elderly male participants, the same tendency was noted. Receiver operating characteristic (ROC) curve analysis indicated that PhA had good predictive ability for sarcopenia in young male, elderly male, young female, and elderly female participants (area under the ROC curve of 0.882, 0.838, 0.865, and 0.850, with cut-off PhA values of 5.95°, 5.04°, 5.02°, and 4.20° for predicting sarcopenia, respectively).

CONCLUSIONS

The PhA reflected muscle quality and exhibited good accuracy in detecting sarcopenia, suggesting its utility as an index for easily measuring muscle quality, which could improve the diagnosis of sarcopenia.

Aerobic capacity and skeletal muscle characteristics in glycogen storage disease IIIa: an observational study

Background

Individuals with glycogen storage disease IIIa (GSD IIIa) (OMIM #232400) experience muscle weakness and exercise limitation that worsen through adulthood. However, normative data for markers of physical capacity, such as strength and cardiovascular fitness, are limited. Furthermore, the impact of the disease on muscle size and quality is unstudied in weight bearing skeletal muscle, a key predictor of physical function. We aim to produce normative reference values of aerobic capacity and strength in individuals with GSD IIIa, and to investigate the role of muscle size and quality on exercise impairment.

Results

Peak oxygen uptake (V̇O₂peak) was lower in the individuals with GSD IIIa than predicted based on demographic data (17.0 (9.0) ml/kg/min, 53 (24)% of predicted, p = 0.001). Knee extension maximum voluntary contraction (MVC) was also substantially lower than age matched predicted values (MVC: 146 (116) Nm, 57% predicted, p = 0.045), though no difference was found in MVC relative to body mass (1.88 (2.74) Nm/kg, 61% of predicted, p = 0.263). There was a strong association between aerobic capacity and maximal leg strength (r = 0.920; p = 0.003). Substantial inter-individual variation was present, with a high physical capacity group that had normal leg strength (MVC), and relatively high V̇O₂peak, and a low physical capacity that display impaired strength and substantially lower V̇O₂peak. The higher physical capacity sub-group were younger, had larger Vastus Lateralis (VL) muscles, greater muscle quality, undertook more physical activity (PA), and reported higher health-related quality of life.

Conclusions

V̇O₂peak and knee extension strength are lower in individuals with GSD IIIa than predicted based on their demographic data. Patients with higher physical capacity have superior muscle size and structure characteristics and higher health-related quality of life, than those with lower physical capacity. This study provides normative values of these important markers of physical capacity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02184-1.

Association of the gut microbiota and fecal short-chain fatty acids with skeletal muscle mass and strength in children

We aimed to investigate whether the gut microbiota and fecal short-chain fatty acids (SCFAs) are associated with skeletal muscle mass and strength in healthy Chinese children aged 6-9 years. In this study, 412 children were enrolled. 16S rRNA gene sequencing was used to characterize the gut microbiota compositions. Fecal SCFAs were quantified using high-performance liquid chromatography. Dual X-ray absorptiometry was used to measure the total body lean soft tissue mass (TSM), total body fat mass (TBF), appendicular skeletal muscle mass (ASM), and appendicular fat mass (AFM). TSM/height² (TSMI), ASM/height² (ASMI), TSM/weight (TSMR), ASM/weight (ASMR), and the ratio of TSM/TBF and ASM/AFM were calculated. Handgrip strength (HGS) was measured using the Jamar® Plus+ Hand Dynamometer. A multiple regression analysis after adjustment for covariates and multiple test correction showed some operational taxonomic units in partial least squares models identified by Multivariate methods with Unbiased Variable selection analysis such as genera of Faecalibacterium, Lachnospira, Lachnospiraceae_ND3007_group, and Lachnospiraceae_UCG-004 were positively correlated with at least one measure of TSM, TSMI, ASM, ASMI, and ASMI Z-score (β: 0.103-0.143, p_FDR : .008-.032) but negatively correlated with at least one measure of TSMR, TSM/TBF, ASMR, ASM/AFM, and ASMR Z-score (β: -0.185 to 0.124, p_FDR  = .008-.045). Children with higher fecal butyric acid, acetic acid, and total SCFA levels exhibited higher TSM, ASM, TSMI, ASMI, and ASMI Z-score and lower TSM/TBF, ASM/AFM, TSMR, ASMR, and ASMR Z-score. However, after additional adjustment for TBF or body mass index, only the associations for Faecalitalea and Pyramidobacter still existed. Mediation analysis suggested that total body fat significantly mediated 66.3%-95.3% of the estimated association of microbiota and SCFAs with TSM, ASM, and ASMI Z-score. Our results suggest that the associations of gut microbiota and SCFAs with skeletal muscle quality in children may largely depend upon on total body fat content.

Comparison of methods to identify individuals with obesity at increased risk of functional impairment among a population of home-dwelling older adults

Obesity is associated with increased muscle mass and muscle strength. Methods taking into account the total body mass to reveal obese older individuals at increased risk of functional impairment are needed. Therefore, we aimed to detect methods to identify obese older adults at increased risk of functional impairment. Home-dwelling older adults (n 417, ≥ 70 years of age) were included in this cross-sectional study. Sex-specific cut-off points for two obesity phenotypes (waist circumference (WC) and body fat mass (FM %)) were used to divide women and men into obese and non-obese groups, and within-sex comparisons were performed. Obese women and men, classified by both phenotypes, had similar absolute handgrip strength (HGS) but lower relative HGS (HGS/total body mass) (P < 0·001) than non-obese women and men, respectively. Women with increased WC and FM %, and men with increased WC had higher appendicular skeletal muscle mass (P < 0·001), lower muscle quality (HGS/upper appendicular muscle mass) (P < 0·001), and spent longer time on the stair climb test and the repeated sit-to-stand test (P < 0·05) than non-obese women and men, respectively. Absolute muscle strength was not able to discriminate between obese and non-obese older adults. However, relative muscle strength in particular, but also muscle quality and physical performance tests, where the total body mass was taken into account or served as an extra load, identified obese older adults at increased risk of functional impairment. Prospective studies are needed to determine clinically relevant cut-off points for relative HGS in particular.

Soft tissue radiodensity parameters mediate the relationship between self-reported physical activity and lower extremity function in AGES-Reykjavík participants

Although previous studies have highlighted the association between physical activity and lower extremity function (LEF) in elderly individuals, the mechanisms underlying this relationship remain debated. Our recent work has recognized the utility of nonlinear trimodal regression analysis (NTRA) parameters in characterizing changes in soft tissue radiodensity as a quantitative construct for sarcopenia in the longitudinal, population-based cohort of the AGES-Reykjavík study. For the present work, we assembled a series of prospective multivariate regression models to interrogate whether NTRA parameters mediate the 5-year longitudinal relationship between physical activity and LEF in AGES-Reykjavík participants. Healthy elderly volunteers from the AGES-Reykjavík cohort underwent mid-thigh X-ray CT scans along with a four-part battery of LEF tasks: normal gait speed, fastest-comfortable gait speed, isometric leg strength, and timed up-and-go. These data were recorded at two study timepoints which were separated by approximately 5 years: AGES-I (n = 3157) and AGES-II (n = 3098). Participants in AGES-I were likewise administered a survey to approximate their weekly frequency of engaging in moderate-to-vigorous physical activity (PAAGES-I). Using a multivariate mediation analysis framework, linear regression models were assembled to test whether NTRA parameters mediated the longitudinal relationship between PAAGES-I and LEFAGES-II; all models were covariate-adjusted for age, sex, BMI, and baseline LEF, and results were corrected for multiple statistical comparisons. Our first series of models confirmed that all four LEF tasks were significantly related to PAAGES-I; next, modelling the relationship between PAAGES-I and NTRAAGES-II identified muscle amplitude (Nm) and location (μm) as potential mediators of LEF to test. Finally, adding these two parameters into our PAAGES-I → LEFAGES-II models attenuated the prior effect of PAAGES-I; bootstrapping confirmed Nm and μm as significant partial mediators of the PAAGES-I → LEFAGES-II relationship, with the strongest effect found in isometric leg strength. This work describes a novel approach toward clarifying the mechanisms that underly the relationship between physical activity and LEF in aging individuals. Identifying Nm and μm as significant partial mediators of this relationship provides strong evidence that physical activity protects aging mobility through the preservation of both lean tissue quantity and quality.

Dietary Protein Intake Is Positively Associated with Appendicular Lean Mass and Handgrip Strength among Middle-Aged US Adults

BACKGROUND

Sarcopenia, a progressive loss of skeletal muscle mass and strength, can begin in the 4th decade of life. Protein intake predicts skeletal muscle mass and strength among older adults, but knowledge of similar associations among middle-aged adults is lacking.

OBJECTIVES

We aimed to assess associations between protein intake and skeletal muscle mass, characterized by appendicular lean mass adjusted for BMI [in kg/m2 (ALMBMI)], and muscle strength, represented by handgrip strength adjusted for BMI (GSMAXBMI), among middle-aged adults.

METHODS

We analyzed cross-sectional data from 1209 men and 1208 women aged 40-59 y in the 2011-2014 NHANES. Protein intake per kilogram actual body weight (BW), assessed by two 24-h recalls, was examined as continuous and categorical parameters [low (<RDA, 0.8 g/kg BW), moderate (≥RDA, <1.2 g/kg BW), and high (≥1.2 g/kg BW)]. ALM was measured using DXA, and GSMAX was measured using handgrip dynamometer. "Low lean mass" and "weakness" were defined using NIH criteria for ALMBMI and GSMAXBMI, respectively. Linear and logistic regression models were performed.

RESULTS

Among middle-aged adults, 15.6% of men and 13.4% of women had low lean mass and 3.5% of men and 2.3% of women exhibited weakness. Protein intakes per kilogram BW were positively associated with ALMBMI and GSMAXBMI among men and women after adjustment for age, race/Hispanic origin, physical activity, and self-rated health. Compared with the moderate protein group, the high protein group had a higher GSMAXBMI and the low protein group had a lower GSMAXBMI among men and women. The low protein group had a lower ALMBMI (women) and had a higher OR for low lean mass (men) compared with the moderate protein group.

CONCLUSIONS

Higher protein intakes were associated with greater ALMBMI and GSMAXBMI in this representative sample of US middle-aged adults. Our findings highlight the need for further research on dietary protein as a potential modifying factor of sarcopenia risk in middle age.

Overcoming protein-energy malnutrition in older adults in the residential care setting: A narrative review of causes and interventions

Malnutrition, in particular protein-energy malnutrition, is a highly prevalent condition in older adults, and is associated with low muscle mass and function, and increased prevalence of physical frailty. Malnutrition is often exacerbated in the residential care setting due to factors including lack of dentition and appetite, and increased prevalence of dementia and dysphagia. This review aims to provide an overview of the available literature in older adults in the residential care setting regarding the following: links between sarcopenia, frailty, and malnutrition (in particular, protein-energy malnutrition (PEM)), recognition and diagnosis of malnutrition, factors contributing to PEM, and the effectiveness of different forms of protein supplementation (in particular, oral nutritional supplementation (ONS) and protein-fortified foods (PFF)) to target PEM. This review found a lack of consensus on effective malnutrition diagnostic tools and lack of universal requirement for malnutrition screening in the residential care setting, making identifying and treating malnutrition in this population a challenge. When assessing the use of protein supplementation in the residential care setting, the two primary forms of supplementation were ONS and PFF. There is evidence that ONS and PFF increase protein and energy intakes in residential care setting, yet compliance with supplementation and their impact on functional status is unclear and conflicting. Further research comparing the use of ONS and PFF is needed to fully determine feasibility and efficacy of protein supplementation in the residential care setting.

A Case Study of an 87-Year-Old Male Bodybuilder with Complex Health Conditions

This exploratory clinical case report presents an 87-year-old man who began bodybuilding at the age of 76 years and was officially recognised as the world’s oldest competitive bodybuilder, competing until age 83. He has a background of complex health conditions including polio, strokes, cardiac arrest, atrial fibrillation, prostate disease, osteoarthritis, depression, bowel obstruction, reflux, and bladder cancer. Assessments of body composition, bone density, muscle performance, and diet-related practices were performed. The bodybuilder had superior fat-free mass, lower fat mass, and generally greater muscle performance compared to untrained healthy males of a similar age. Commencement of bodybuilding in older age appears to be possible, even with ongoing complex health conditions, and the potential benefits of this practice require systematic investigation in the future.

Lung function and respiratory muscle strength and their relationship with weightlifting strength and body composition in non-athletic males

The aim of this study was to examine whether lung function and respiratory muscle strength are associated with weightlifting strength and body composition in non-athletic males. A total 51 males with resistance training experience participated. One-repetition maximum tests were performed for the bench press, squat and deadlift and body composition was assessed. Lung function was evaluated with a pulmonary testing system and respiratory muscle strength was assessed with a handheld mouth-pressure manometer. Moderate to strong positive relationships were found between all weightlifting strength variables and maximal expiratory pressure (r = 0.36-0.54, p = ≤0.01). Small to strong positive correlations were found between fat-free mass, appendicular lean mass and most lung function variables (r = 0.29-0.54, p ≤ 0.039). However, fat-free mass and appendicular lean mass indexes were only related with respiratory muscle strength and not lung function. Expiratory muscle strength appears to influence weightlifting performance. Special exercises targeting the expiratory muscles may assist with improving weightlifting performance, especially for squats and deadlifts.

Prevalence of Sarcopenia Employing Population-Specific Cut-Points: Cross-Sectional Data from the Geelong Osteoporosis Study, Australia

Background: Prevalence estimates for sarcopenia vary depending on the ascertainment criteria and thresholds applied. We aimed to estimate the prevalence of sarcopenia using two international definitions but employing Australian population-specific cut-points. Methods: Participants (n = 665; 323 women) aged 60–96 years old were from the Geelong Osteoporosis Study. Handgrip strength (HGS) was measured by dynamometers and appendicular lean mass (ALM) by whole-body dual-energy X-ray absorptiometry. Physical performance was assessed using gait speed (GS, men only) and/or the timed up-and-go (TUG) test. Using cut-points equivalent to two standard deviations (SDs) below the mean young reference range from the same population and recommendations from the European Working Group on Sarcopenia in Older People (EWGSOP), sarcopenia was identified by low ALM/height² (<5.30 kg for women; <6.94 kg for men) + low HGS (<16 kg women; <31 kg men); low ALM/height² + slow TUG (>9.3 s); low ALM/height² + slow GS (<0.8 m/s). For the Foundation for the National Institutes of Health (FNIH) equivalent, sarcopenia was identified as low ALM/BMI (<0.512 m² women, <0.827 m² men) + low HGS (<16 kg women, <31 kg men). Receiver Operating Characteristic curves were also applied to determine optimal cut-points for ALM/BMI (<0.579 m² women, <0.913 m² men) that discriminated poor physical performance. Prevalence estimates were standardized to the Australian population and compared to estimates using international thresholds. Results: Using population-specific cut-points and low ALM/height² + HGS, point-estimates for sarcopenia prevalence were 0.9% for women and 2.9% for men. Using ALM/height² + TUG, prevalence was 2.5% for women and 4.1% for men, and using ALM/height² + GS, sarcopenia was identified for 1.6% of men. Using ALM/BMI + HGS, prevalence estimates were 5.5–10.4% for women and 11.6–18.4% for men. Conclusions: This study highlights the range of prevalence estimates that result from employing different criteria for sarcopenia. While population-specific criteria could be pertinent for some populations, a consensus is needed to identify which deficits in skeletal muscle health are important for establishing an operational definition for sarcopenia.

Functional tests associated with sarcopenia in moderate chronic obstructive pulmonary disease

Objectives: To evaluate the association of physical and functional measures with sarcopenia in moderate chronic obstructive pulmonary disease (COPD) and to establish cutoff points for sarcopenia screening.Methods: The study included COPD with and without sarcopenia, of both sexes who were over 50 years old. Participants were assessed for lung function, body composition, grip strength, Short Physical Performance Battery (SPPB), 5-repetition, 10-repetition and 30-s sit-to-stand tests (5STS, 10STS, and 30STS, respectively). In addition, 6-min walking test, respiratory muscular strength, and physical activity level were tested.Results: The study had 35 participants, 24 men (68.6%) and moderate COPD (51.4%). COPD-sarcopenia showed lower values in lean mass, body fat and body mass alongside lower performance in 10 and 30 STS tests, SPPB and gait speed compared to non-sarcopenic group. The cutoff points with better sensitivity and specificity to identify sarcopenia were 10.88 and 34.14 s, 15 repetitions, and 10 points in the 5STS, 10STS, 30STS, and SPPB, respectively. The comparison of the receiver operating curves evidenced no differences between the functional tests. Only 30STS and SPPB showed acceptable discriminatory power.Conclusion: Functional tests, especially 30STS and SPPB, are simple and affordable tools for screening sarcopenia in COPD with moderate obstruction.

New insights on how and where to measure muscle mass

PURPOSE OF REVIEW

This article will discuss different muscle mass assessment methods and emphasize their highlights.

RECENT FINDINGS

Several measurement techniques can be used to evaluate muscle mass, recognized as important prognostic markers for adverse functional and clinical outcomes. Choosing the best method depends on the knowledge regarding their theoretical and practical limitations and the purpose of the assessment. Image techniques are considered the gold standards, with good accuracy and precision, but not always available in clinical settings. A new biological technique, the D3-creatinine dilution, can provide not only direct information about muscle mass but also shows a strong association with physical function. With the advancement of the use of the computed tomography (CT) images to assess skeletal muscle mass, mainly in patients with cancer, the assessment of skeletal muscle radiodensity (SMD), as a marker of muscle quality, may provide additional information regarding the association between muscle composition, muscle function and prognosis. Additional muscle function assessment can improve the risk prediction in several clinical situations.

SUMMARY

The use of the best tool for the muscle mass assessment should be performed carefully among the various methodologies, according to their characteristics and clinical situation.

Novel Essential Amino Acid Supplements Following Resistance Exercise Induce Aminoacidemia and Enhance Anabolic Signaling Irrespective of Age: A Proof-of-Concept Trial

We investigated the effects of ingesting a leucine-enriched essential amino acid (EAA) gel alone or combined with resistance exercise (RE) versus RE alone (control) on plasma aminoacidemia and intramyocellular anabolic signaling in healthy younger (28 ± 4 years) and older (71 ± 3 years) adults. Blood samples were obtained throughout the three trials, while muscle biopsies were collected in the postabsorptive state and 2 h following RE, following the consumption of two 50 mL EAA gels (40% leucine, 15 g total EAA), and following RE with EAA (combination (COM)). Protein content and the phosphorylation status of key anabolic signaling proteins were determined via immunoblotting. Irrespective of age, during EAA and COM peak leucinemia (younger: 454 ± 32 µM and 537 ± 111 µM; older: 417 ± 99 µM and 553 ± 136 µM) occurred ~60–120 min post-ingestion (younger: 66 ± 6 min and 120 ± 60 min; older: 90 ± 13 min and 78 ± 12 min). In the pooled sample, the area under the curve for plasma leucine and the sum of branched-chain amino acids was significantly greater in EAA and COM compared with RE. For intramyocellular signaling, significant main effects were found for condition (mTOR (Ser2481), rpS6 (Ser235/236)) and age (S6K1 (Thr421/Ser424), 4E-BP1 (Thr37/46)) in age group analyses. The phosphorylation of rpS6 was of similar magnitude (~8-fold) in pooled and age group data 2 h following COM. Our findings suggest that a gel-based, leucine-enriched EAA supplement is associated with aminoacidemia and a muscle anabolic signaling response, thus representing an effective means of stimulating muscle protein anabolism in younger and older adults following EAA and COM.

Handgrip strength and muscle quality in Australian women: cross-sectional data from the Geelong Osteoporosis Study

BACKGROUND

Low handgrip strength (HGS) is a measure of poor skeletal muscle performance and a marker of ill health and frailty. Muscle quality (MQ) is a measure of muscle strength relative to muscle mass. We aimed to develop normative data for HGS and MQ, report age-related prevalence of low HGS and MQ, and determine the relationship with age, anthropometry, and body composition for women in Australia.

METHODS

This cross-sectional analysis included data from 792 women (ages 28-95 years) assessed by the Geelong Osteoporosis Study. Duplicate measures of HGS were performed for each hand with a dynamometer (Jamar) and the mean of maximum values used for analyses. Dual energy X-ray absorptiometry-derived lean mass for the arms was used to calculate MQ as HGS/lean mass (kg/kg). Body mass index (BMI) was categorized as normal (BMI < 25.0 kg/m2 ), overweight (25.0-29.9 kg/m2 ), and obese (>30.0 kg/m2 ). Fat mass index (FMI) was calculated as whole body fat/height2 (kg/m2 ) and appendicular lean mass index (ALMI) as lean mass of arms and legs/height2 (kg/m2 ).

RESULTS

Mean (±SD) of HGS values for normal BMI, overweight, and obese groups were 25 (±7), 24 (±7), and 24 (±7) kg, P = 0.09, and for MQ, 12 (±3), 11 (±3), and 10 (±3) kg/kg, P < 0.001. Our data indicated a quadratic relationship between age and HGS or MQ. Mean HGS and MQ remained stable until the fifth age decade then declined steadily with increasing age; therefore, we used data for women (n = 283) aged 28-49 years as the young adult reference group, with mean (SD) values for HGS 28 (±6) kg and MQ 12 (±3) kg/kg. The prevalence of low (T-score < -2) HGS and MQ for women 80 years and older was 52.2% and 39.6%, respectively. In multivariable models, age-adjusted HGS was associated with FMI (B = -0.13, P = 0.004) and ALMI (1.03, <0.001) while age-adjusted MQ was associated with BMI (-0.15, <0.001) but not with FMI. In a sensitivity analysis, the same pattern remained after the removal of 129 women who reported hand and/or arm pain.

CONCLUSIONS

Mean HGS and MQ declined with advancing age in older women. Our data suggest that while mean HGS increased with appendicular lean mass and decreased with body fat mass, there was no association with BMI. By contrast, MQ decreased with increasing BMI, but not with increasing adiposity.

Effects of Changes in Ankle Joint Angle on the Relation Between Plantarflexion Torque and EMG Magnitude in Major Plantar Flexors of Male Chronic Stroke Survivors

The slope of the EMG-torque relation is potentially useful as a parameter related to muscular contraction efficiency, as a greater EMG-torque slope has often been reported in stroke-impaired muscles, compared to intact muscles. One major barrier limiting the use of this parameter on a routine basis is that we do not know how the EMG-torque slope is affected by changing joint angles. Thus, the primary purpose of this study is to characterize the EMG-torque relations of triceps surae muscles at different ankle joint angles in both paretic and non-paretic limbs of chronic hemispheric stroke survivors. Nine male chronic stroke survivors were asked to perform isometric plantarflexion contractions at different contraction intensities and at five different ankle joint angles, ranging from maximum plantarflexion to maximum dorsiflexion. Our results showed that the greater slope of the EMG-torque relations was found on the paretic side compared to the non-paretic side at comparable ankle joint angles. The EMG-torque slope increased as the ankle became plantarflexed on both sides, but an increment of the EMG-torque slope (i.e., the coefficient a) was significantly greater on the paretic side. Moreover, the relative (non-paretic/paretic) coefficient a was also strongly correlated with the relative (paretic/non-paretic) maximum ankle plantarflexion torque and with shear wave speed in the medial gastrocnemius muscle. Conversely, the relative coefficient a was not well-correlated with the relative muscle thickness. Our findings suggest that muscular contraction efficiency is affected by hemispheric stroke, but in an angle-dependent and non-uniform manner. These findings may allow us to explore the relative contributions of neural factors and muscular changes to voluntary force generating-capacity after stroke.

Moderate Increase in Protein Intake Promotes a Small Additional Improvement in Functional Capacity, But Not in Muscle Strength and Lean Mass Quality, in Postmenopausal Women Following Resistance Exercise: A Randomized Clinical Trial

The aim of this study was to evaluate the effect of a moderate increase in protein intake on muscle strength, functional capacity and lean mass quality improvements in postmenopausal women following resistance exercise. Forty-seven postmenopausal women were randomized in two groups: Normal protein (NP, n = 25), who received a dietary plan containing ~0.8 g protein·kg^-1·d^-1 (recommended dietary allowance-RDA recommendations); and higher protein (HP, n = 22), which a moderate increase in protein intake was recommended (~1.2 g protein·kg^-1·d^-1). Resistance training was performed for 10 weeks, three times/week. Muscle strength (handgrip strength and one repetition maximum test-1-RM), functional capacity and lean mass (LM) quality (muscle strength to lean mass ratio) were evaluated. Dietary intake was assessed by nine 24 h food recalls. After intervention, both groups increased similarly the leg extension 1-RM and handgrip strength. Regarding functional capacity tests, both groups increased the balance test score (SPPB) and 10 m walk test speed, with no differences between the groups. In addition, an increase in speed to perform the 6 min and 400 m walk tests was observed over the time, with an additional improvement in the HP group (time × group interaction; p = 0.007 and p = 0.004, respectively). About LM quality, leg extension 1-RM/leg LM improved over the time in both groups (p = 0.050), with no time × group interaction. All these significant changes had a low effect size. In conclusion, a moderate increase in protein intake promoted a small additional improvement in functional capacity, but it did not induce a greater increase in strength and LM quality after 10 weeks of resistance exercise in postmenopausal women. This trial was registered at ClinicalTrials.gov as NCT03024125.