Longitudinal muscle strength changes in older adults: influence of muscle mass, physical activity, and health

Age-related trajectories of muscle strength and power in individuals with cerebral palsy and the relationship to walking capacity

BACKGROUND

Cessation of walking is a consequence of aging in many individuals with Cerebral Palsy (CP). Muscle strength and power are associated with walking capacity in those with CP. However, the age-related trajectories in strength and power and how they compare to trajectories of those with typical development (TD) are unknown. Additionally, determining which measure of muscle performance (strength or power) is more closely associated with walk capacity may guide clinical assessments of muscle performance that are most meaningful to mobility in those with CP.

RESEARCH QUESTION

Do the associations between age and muscle performance differ between individuals with CP and TD? Is muscle power more strongly associated with walking capacity compared to muscle strength in those with CP?

METHODS

Age-related differences in muscle strength and power between individuals with CP (n = 66, 13.5 ± 4.8 years, GMFCS I-IV) and TD (n = 42, 16.8 ± 6.1 years) were examined with linear regression and ANCOVA. Associations between measures of walking capacity and strength and power were evaluated with Pearson's (r).

RESULTS

Linear regression between muscle strength and power with age was statistically significant in both groups. Age-related changes in strength and power were significantly greater in TD compared to CP. Linear regression between normalized strength and power with age was significant in those with TD but not in CP. All measures of walking capacity were significantly associated with both strength and power, but muscle power was more strongly correlated (p < 0.05).

SIGNIFICANCE

Although age-related changes were observed in both groups, individuals with TD demonstrated greater age-related changes in muscle power and strength than those with CP. After normalizing by body mass, no age-related changes were observed in CP, suggesting that gains in power and strength are insufficient to offset increases in body mass with age. Muscle power had a stronger relationship to walking capacity than strength.

Gender-specific sarcopenia screening in hemodialysis: insights from lower limb strength and physiological indicators

OBJECTIVE

Maintenance hemodialysis (MHD) patients often suffer from sarcopenia, affecting lower limb muscle strength and increasing the risk of falls and mortality. This study aims to develop an auxiliary screening model for sarcopenia in MHD patients based on machine learning methods, utilizing lower limb muscle strength indicators, while paying attention to the gender difference and exploring its value in sarcopenia screening.

METHODS

This cross-sectional study collected data from MHD patients at a hemodialysis center in China. Sarcopenia was assessed using the 2019 Asian Working Group for Sarcopenia update. A self-developed lower limb muscle strength testing device was used. Other physiological indicators, including basic information and lab findings, were collected. Participants were grouped into sarcopenia and control groups, with gender-specific binary classification models developed. Stratified shuffling and synthetic minority oversampling techniques were used to build screening classifiers.

RESULTS

Data from 164 MHD patients were ultimately collected, including 83 males (41 with possible sarcopenia or sarcopenia) and 81 females (53 with possible sarcopenia or sarcopenia). Gender-specific binary classification models were developed using lower limb muscle strength indicators, with the male model having an AUC of 79% and the female model an AUC of 80%, respectively. Combining lower limb muscle strength with other physiological indicators improved the female model's screening capability, achieving an AUC of 90%.

CONCLUSION

This study demonstrates that the auxiliary screening model for sarcopenia, developed using machine learning methods, highlights the significant value of lower limb muscle strength indicators in identifying sarcopenia in MHD patients. The gender-specific screening models show good discriminatory ability across different genders, providing effective tools for the early screening and management of sarcopenia in MHD patients.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR2100051111), registered on 2021-09-13.

The contribution of age and sex hormones to female neuromuscular function across the adult lifespan

Neuromuscular ageing is characterized by neural and/or skeletal muscle degeneration that decreases maximal force and power. Female neuromuscular ageing occurs earlier in life compared to males, potentially due to sex hormone changes during the menopausal transition. We quantified neuromuscular function in 88 females represented equally over each decade from 18 to 80 years of age and investigated the role of decreased ovarian hormone concentrations following menopause. Neuromuscular assessment included quadriceps maximal voluntary and evoked isometric torque and surface electromyography measurements, plus one-repetition maximum leg press. Voluntary and evoked torques and one-repetition maximum decreased non-linearly with age, with accelerated reductions starting during the fourth decade. An absence of changes in volitional recruitment of existing quadriceps motor units and Ia afferent facilitation of spinal motoneurons suggests that functional decline was largely mediated by impairment in intrinsic peripheral muscle function and/or neuromuscular transmission. Maximal muscle compound action potential amplitude decreased with increasing age for rectus femoris muscle only, indicating increased vulnerability to neuromuscular degeneration compared to vastus lateralis and medialis. In postmenopausal females, some variance was explained by inter-individual differences in quadriceps tissue composition and lifestyle factors, but changes in total or free concentrations of oestradiol, progesterone and/or testosterone were included in all correlations with age-related decreases in isometric voluntary and evoked torques. We demonstrate an accelerated onset of neuromuscular degeneration of peripheral muscular origin around menopause onset associated with changes in sex hormone concentrations. Interventions aimed at mitigating declines in ovarian hormones and their subsequent effects on neuromuscular function after menopause should be further explored. KEY POINTS: Neuromuscular deterioration with age is associated with poor physical function and quality of life in older adults, but female-specific trajectories and mechanisms remain unclear. This study is the first to map neuromuscular function across each decade of the adult lifespan in 88 females from 18 to 80 years old and to examine the potential role of hormonal changes after menopause. We show an accelerated reduction in neuromuscular function, primarily of peripheral muscular origin, that occurs during the fourth decade and coincides with menopause onset. In postmenopausal females, age-related reductions in neuromuscular function can in part be explained by quadriceps lean and intramuscular fat composition, physical activity and protein intake, and sex hormone concentrations. These findings help us better understand the factors that contribute to the loss of neuromuscular function with age in females, enabling the identification of potential therapeutic interventions to prolong female health span.

Genetic Liability to Higher Muscle Strength Associates With a Lower Risk of Cardiovascular Disease Mortality in Men Irrespective of Leisure-Time Physical Activity in Adulthood: A Longitudinal Cohort Study

BACKGROUND

Low muscle strength predicts premature mortality. We determined whether genetic liability to muscle strength is associated with mortality and whether this association is influenced by long-term leisure-time physical activity (LTPA).

METHODS AND RESULTS

We estimated the effects of a polygenic score for handgrip strength (PGS HGS) on all-cause and cardiovascular disease (CVD) mortality risk in the older Finnish Twin Cohort (N=8815, 53% women). LTPA was assessed longitudinally using validated questionnaires. During the 16.9-year median follow-up (143 723 person-years), 2896 deaths occurred, of which 1089 were attributable to CVD. We found a significant interaction between sex and PGS HGS (P=0.016) in relation to all-cause mortality. In men, 1-SD increase in the PGS HGS was associated with a decreased risk of all-cause (hazard ratio [HR], 0.93 [95% CI, 0.89-0.98]) and CVD mortality (HR, 0.88 [95% CI, 0.81-0.96]), but was not statistically significantly associated with mortality in women (HR, 1.01 [95% CI, 0.96-1.07]; and HR, 0.96 [95% CI, 0.87-1.05], respectively). In men, associations remained after adjusting for LTPA and persisted for CVD mortality (HR, 0.85 [95% CI, 0.76-0.96]), even after accounting for other lifestyle covariates. This remained statistically significant even when non-CVD death was accounted for as a competing risk event. No PGS HGS×LTPA interactions were found. The predictive area under the curve estimates for PGS HGS alone were limited (0.53-0.64) but comparable to that of several lifestyle factors.

CONCLUSIONS

Higher PGS HGS was associated with a decreased risk of CVD mortality in men. Long-term LTPA in adulthood did not potentiate this association.

Prevalence and coexistence of locomotive syndrome with reduced mobility and metabolic syndrome: a cross-sectional study of 35,059 Japanese adults

Metabolic syndrome (MetS), marked by visceral obesity, hypertension, hyperglycemia, and dyslipidemia, elevates cardiovascular risk. Locomotive syndrome (LS), characterized by age-related mobility decline, often precedes frailty and sarcopenia. We investigated the prevalence and association between MetS and LS among Japanese middle-aged and older adults. This retrospective cross-sectional study was conducted using clinical records of 35,059 Japanese adults who underwent health check-ups between April 2021 and March 2022. MetS was diagnosed using the modified National Cholesterol Education Program Adult Treatment Panel III criteria, and LS was assessed using the LS risk test, which includes the stand-up test, two-step test, and the 25-question Geriatric Locomotive Function Scale. Among the participants, 2640 (7.5%) were diagnosed with MetS, and 5265 (15.0%) were classified as LS-positive. The prevalence of LS was significantly higher in individuals with MetS. The association between MetS and LS remained significant after adjusting for age and sex. We found that LS prevalence was higher in women than in men, though the primary association between MetS and LS remained consistent across both sexes. This large-scale real-world analysis emphasizes the need for integrating LS screening into routine check-ups to detect and manage MetS, aiding in the prevention of functional decline in aging populations.

Long-term effects of s-KL treatment in wild-type mice: Enhancing longevity, physical well-being, and neurological resilience

Aging is a major risk factor for pathologies including sarcopenia, osteoporosis, and cognitive decline, which bring suffering, disability, and elevated economic and social costs. Therefore, new therapies are needed to achieve healthy aging. The protein Klotho (KL) has emerged as a promising anti-aging molecule due to its pleiotropic actions modulating insulin, insulin-like growth factor-1, and Wnt signaling pathways and reducing inflammatory and oxidative stress. Here, we explored the anti-aging potential of the secreted isoform of this protein on the non-pathological aging progression of wild-type mice. The delivery of an adeno-associated virus serotype 9 (AAV9) coding for secreted KL (s-KL) efficiently increased the concentration of s-KL in serum, resulting in a 20% increase in lifespan. Notably, KL treatment improved physical fitness, related to a reduction in muscle fibrosis and an increase in muscular regenerative capacity. KL treatment also improved bone microstructural parameters associated with osteoporosis. Finally, s-KL-treated mice exhibited increased cellular markers of adult neurogenesis and immune response, with transcriptomic analysis revealing induced phagocytosis and immune cell activity in the aged hippocampus. These results show the potential of elevating s-KL expression to simultaneously reduce the age-associated degeneration in multiple organs, increasing both life and health span.

Assessment of Age-Related Differences in Lower Leg Muscles Quality Using Radiomic Features of Magnetic Resonance Images

Sarcopenia, characterised by a decline in muscle mass and strength, affects the health of the elderly, leading to increased falls, hospitalisation, and mortality rates. Muscle quality, reflecting microscopic and macroscopic muscle changes, is a critical determinant of physical function. To utilise radiomic features extracted from magnetic resonance (MR) images to assess age-related changes in muscle quality, a dataset of 24 adults, divided into older (male/female: 6/6, 66-79 years) and younger (male/female: 6/6, 21-31 years) groups, was used to investigate the radiomics features of the dorsiflexor and plantar flexor muscles of the lower leg that are critical for mobility. MR images were processed using MaZda software for feature extraction. Dimensionality reduction was performed using principal component analysis and recursive feature elimination, followed by classification using machine learning models, such as support vector machine, extreme gradient boosting, and naïve Bayes. A leave-one-out validation test was used to train and test the classifiers, and the area under the receiver operating characteristic curve (AUC) was used to evaluate the classification performance. The analysis revealed that significant differences in radiomic feature distributions were found between age groups, with older adults showing higher complexity and variability in muscle texture. The plantar flexors showed similar or higher AUC than the dorsiflexors in all models. When the dorsiflexor muscles were combined with the plantar flexor muscles, they tended to have a higher AUC than when they were used alone. Radiomic features in lower-leg MR images reflect ageing, especially in the plantar flexor muscles. Radiomic analysis can offer a deeper understanding of age-related muscle quality than traditional muscle mass assessments.

Change in D3Cr muscle mass in oldest old men and its association with changes in grip strength and walking speed

BACKGROUND

The use of lean soft tissue (LST) mass as a surrogate measurement of skeletal muscle mass (SMM) has led to the conclusion that muscle loss is poorly related to functional decline. We hypothesized that when using a more accurate measure of SMM determined by D3-creatine dilution (D3Cr), longitudinal changes in SMM will be similar in magnitude to changes in strength and physical performance and that skeletal muscle mass will partially mediate the relationship of age with these outcomes.

METHODS

We measured change in D3Cr muscle mass (kg), handgrip strength (kg), and 6m walk speed (m/s) in 208 men from the Osteoporotic Fractures in Men Study (85.2 ± 4.3 years) over an average of 6.1 years follow-up. Mixed linear effects models adjusted for potential confounders were used to examine the relationship of changes in D3Cr muscle mass with changes in grip strength and walking speed.

RESULTS

Annual losses of D3Cr muscle mass, grip strength, and walking speed were 2.1%, 2.2%, and 2.6%, respectively (p < 0.001). Each additional kg loss in D3Cr muscle mass was associated with a 0.55 kg loss in grip strength and a 0.01 m/s loss in walking speed independent of changes in age (p < 0.001). 41.3% and 22.4% of the relationship between age and loss of grip strength and walking speed, respectively, was attributed to loss of D3Cr muscle mass (p < 0.001).

CONCLUSION

Skeletal muscle mass may have a more important role than previously considered and should not be overlooked as a potentially modifiable determinant in the loss of strength and performance in older age.

Glomerular Filtration of Creatinine: Validation of a Novel Index of Muscle Mass Among Older Adults

RATIONALE & OBJECTIVE

Low muscle mass is common among older adults and associated with poor prognosis. Quantifying muscle mass is challenging in routine clinical practice. We hypothesized that glomerular filtration of creatinine (GFcr) reflects muscle mass, and previously proposed estimated GFcr (eGFcr), as a practical index of muscle mass in older adults. This study investigated whether measured GFcr (mGFcr) and eGFcr are similarly associated with the direct measure of muscle mass, the thigh total muscle lean area (TTMLA).

STUDY DESIGN

Cross-sectional analysis of a community-based prospective cohort.

SETTING & PARTICIPANTS

A total of 794 older adults with measured glomerular filtration rate (mGFR) and TTMLA in the AGES-Reykjavik Study.

EXPOSURE

Measured GFcr, the product of serum creatinine (Scr) and mGFR obtained using plasma iohexol clearance and eGFcr, the product of Scr and estimated glomerular filtration rate using serum cystatin C (Scys).

OUTCOME

TTMLA measured using computed tomography.

ANALYTICAL APPROACH

Sex-specific Pearson's correlation and linear regression analyses using continuous and categorical mGFcr and eGFcr. Covariates included demographic, behavioral, and clinical variables, and comorbid conditions.

RESULTS

The mean age and mGFR were 80.3±4.0 (SD) years and 62.3±16.5 (SD) mL/min/1.73m2, respectively. The lowest sex-specific tertile of mGFcr, compared with the highest tertile, was associated with a 14.6 (95% CI, 11.5-17.6) cm2/1.73m2 lower TTMLA in men, and a 7.9 (95% CI, 5.5-10.2) cm2/1.73m2 lower TTMLA in women. Significant associations were observed between eGFcr and TTMLA. Correlations of eGFcr with TTMLA were generally as strong or stronger than correlations of alternative indices derived from Scr and Scys.

LIMITATIONS

Residual confounding by measured and unmeasured variables.

CONCLUSIONS

These findings support the validity of GFcr as an index of muscle mass among older adults and the use of eGFcr as a practical alternative to mGFcr in the clinical setting.

PLAIN-LANGUAGE SUMMARY

Low muscle mass is common among older adults and is associated with poor clinical outcomes. Quantifying muscle mass is challenging in routine clinical practice. We evaluated whether glomerular filtration of creatinine (GFcr) could serve as an index of muscle mass. We performed a cross-sectional study including 794 older adults who underwent computed tomography for thigh muscle lean area as a directly measured indicator of total body muscle mass. Significant positive associations between thigh muscle lean area and both measured GFcr (serum creatinine [Scr] ×measured glomerular filtration rate [GFR]) and estimated GFcr (Scr ×estimated GFR based on serum cystatin C [Scys]), a more practical index, were shown. These findings suggest the value of using eGFcr, a simply obtained novel index in the clinical setting, to assess muscle mass among older adults.

Age Difference in the Association Between Nutritional Status and Dynapenia in Older Adults

BACKGROUND

Although nutritional status plays a critical role in maintaining muscle strength, limited evidence exists regarding its association with dynapenia.

OBJECTIVES

We aimed to investigate the association between different nutritional statuses and dynapenia among Taiwanese older adults, and assessed whether age modifies this relationship.

METHODS

In this study, we enrolled individuals aged 65 years and older living in community settings through convenience sampling from 2020 to 2021, following a cross-sectional design. The Mini-Nutritional Assessment Short Form (MNA-SF) was used to assess whether the participants were at nutritional risk. Standardized assessments measured muscle strength (handgrip measurement), physical performance (6 m walking test), and muscle mass (bioelectrical impedance analysis) to confirm dynapenia classifications. The interaction terms were tested using likelihood ratio tests to examine for dynapenia between nutritional status and age. For overall sample and subgroup analyses, binary logistic regression was employed.

RESULTS

Among 211 participants (mean age: 80.7 ± 7.1 years), after adjusting for potential confounders, those at nutritional risk (OR: 3.11; 95% CI: 1.31-7.36) were positively associated with dynapenia, whereas higher MNA-SF scores (OR: 0.73; 95% CI: 0.57-0.93) were negatively associated. Interactions regarding dynapenia were observed between nutritional status and age group (p = 0.014), with nutritional risk significantly associated with dynapenia only in the old-old group (≥75 years) (OR = 4.11, 95% CI: 1.39-12.15).

CONCLUSIONS

Age is a potential moderator of nutritional status and dynapenia among older populations. Nutritional status appeared to be more profound in the old-old group in terms of the risk of dynapenia. These findings offer insights for monitoring nutritional status and implementing targeted interventions to prevent dynapenia in those aged over 75 years. Future studies using prospective designs should explore the underlying mechanisms linking nutritional status to dynapenia and assess the effectiveness of nutritional interventions in preventing muscle strength decline.

Risk factors of stroke-related sarcopenia: a systematic review and meta-analysis

Background

The presence of sarcopenia at the time of stroke may deteriorate the rehabilitation and functional outcomes. There is no consensus on the factors associated with stroke-related sarcopenia because previous studies produced inconsistent and disputed results. Therefore, we screened the possible risk factors by meta-analysis.

Methods

Studies published before March 2024 on risk factors with stroke-related sarcopenia were searched through PubMed, Embase, Web of Science, CINAHL, Cochrane Library, CNKI, Wan Fang, CBM, and VIP library databases. Two researchers independently screened the articles to extract the information and to evaluate their quality. Meta-analysis was then performed using Revman 5.4 software to determine the significant risk factors for patients with stroke-related sarcopenia.

Results

A total of 14 studies (n = 3,113) were selected to determine the following factors that were statistically significant in patients with stroke-related sarcopenia: Age (OR = 1.04; 95% CI: 1.02, 1.06; P < 0.0001), tube feeding (OR = 3.98; 95% CI: 2.12, 7.47; P < 0.0001), pre-stroke sarcopenia (OR = 1.84; 95% CI: 1.39, 2.43; P < 0.0001), atrial fibrillation (OR = 1.53; 95% CI: 1.15, 2.02; P = 0.003), NIHSS score (OR = 1.48; 95% CI: 1.21, 1.81; P = 0.0001), and osteoporosis (OR = 1.801; 95% CI: 58, 2.04; P < 0.00001). BMI (P = 0.71), FOIS (P = 0.80), time since stroke (P = 0.34), and calf circumference reduction (P = 0.48) were not identified as risk or protective factors after stroke (P < 0.05).

Conclusion

Our results identified various risk factors for stroke-related sarcopenia which should be considered and studied by healthcare organizations and professionals to improve the health of stroke patients.

Systematic Review Registration

PROSPERO, Identifier CRD42024545757.

Changes in muscle performance among older adults with myeloid malignancies engaging in a mobile health (mHealth) exercise intervention: a single arm pilot study

BACKGROUND

Older adults with cancer are vulnerable to declines in muscle performance (e.g., strength, speed, duration of muscular contraction), which are associated with worse cancer-related outcomes. Exercise-based interventions can mitigate these declines, but evidence of their effect among older adults with myeloid malignancies receiving outpatient treatment is limited. We explore change in muscle performance among patients in a single arm pilot study of a mobile health (mHealth) exercise intervention.

METHODS

Patients ≥ 60 years old with myeloid malignancies receiving outpatient chemotherapy completed a home-based resistance band and walking exercise program [EXercise for Cancer Patients (EXCAP)©®] delivered via a mobile application with symptom monitoring [(Geriatric Oncology-EXCAP (GO-EXCAP)] lasting 2 cycles of chemotherapy (approximately 8-12 weeks). Clinical exercise physiologists provided instruction and ongoing support. Upper and lower extremity peak torque (maximum force, newton-meters, Nm), total work (force over entire movement, Nm), and average power (speed of force, watts, W) were assessed using the BIODEX System 4 isokinetic dynamometer. Muscle activation (motor recruitment, millivolts, mV) was captured using the BTS FREEEMG 1000. We report descriptive statistics and within-patient differences from baseline to post-intervention using Wilcoxon signed rank tests (α = 0.10) and effect size (ES, Cohen's d, 0.20 ≤ small < 0.50, large ≥ 0.80), and explore differences by exercise level (resistance exercise, daily steps).

RESULTS

A total of 25 patients completed baseline assessments, 23 with muscle performance data at baseline, 16 at post-intervention. Of these, most were male (n = 10, 62.5%) and had acute myeloid leukemia (n = 9, 56.3%). From baseline to post-intervention there were improvements in left shoulder peak torque [mean change = 2.45 (Standard Deviation = 2.41), p = 0.004] and average power [2.29 (3.05), p = 0.033]. Muscle activation increased for left rectus femoris [0.04 (0.04), p = 0.074], right and left biceps brachii [0.03 (0.04), p = 0.012; 0.03 (0.05), p = 0.098, respectively], and left pectoralis major [0.02 (0.03), p = 0.064]. Several measures of peak torque/total work and all measures of muscle activation showed ES ≥ 0.20 for improvement. There were no statistically significant decreases from baseline to post-intervention.

CONCLUSIONS

Older adults with myeloid malignancies participating in a mHealth exercise intervention had stable to improved muscle performance. Further research is needed to establish the preliminary efficacy of this intervention for improving physical performance in this population at high risk for decline.

TRIAL REGISTRATION

clinicaltrials.gov NCT04035499 (registered July 29th, 2019).

Inflammation mediates the association between muscle mass and accelerated phenotypic aging: results from the NHANES 2011-2018

Background

Muscle mass plays a pivotal role in health maintenance, yet its connection to biological aging remains underexplored. This study investigates the association between appendicular skeletal muscle mass index (ASMI) and phenotypic age(PhenoAge), while examining the mediating role of systemic inflammation.

Methods

The analysis included 7,440 participants from the NHANES 2011-2018. Phenotypic Age Acceleration (PhenoAgeAccel) was calculated as the residuals from regressing PhenoAge on chronological age. Multivariable linear regression analyses were performed to assess the association between ASMI and PhenoAgeAccel. Mediation analysis was conducted to quantify the extent to which systemic inflammation contributes to this association.

Results

Our analysis revealed that higher ASMI is linked to slower biological aging, as evidenced by lower PhenoAgeAccel (β = -0.48, 95% CI: -0.66 to -0.29, p = 0.0001). Systemic inflammation partially mediated this effect, with a mediation proportion of 35.1%. The association varied notably across demographic and health-related subgroups, being particularly significant in females, individuals with obesity, and those with lower physical activity.

Conclusion

These findings highlight the critical importance of muscle mass in slowing biological aging, with systemic inflammation emerging as a key biological mediator. The public health implications are substantial, suggesting that targeted interventions-such as resistance training, anti-inflammatory diets, and personalized medical approaches-could play a pivotal role in decelerating biological aging and improving long-term health outcomes.

Impact of Handgrip Strength on Survival in Hemodialysis Patients

Background: Hemodialysis patients face a high mortality risk, requiring effective clinical assessments. In these patients, muscle wasting due to protein-energy wasting (PEW) leads to increased frailty, which is strongly associated with worse outcomes, including higher mortality. As muscle mass declines, so does functional capacity, making regular assessment of both muscle mass and function critical for prognostic evaluation. Handgrip strength (HGS) offers a quick and reliable measure of muscle strength and functional capacity. In this study, we focused on the impact of HGS on survival in hemodialysis patients, analyzing its relationship with muscle mass and BMI. Methods: This retrospective cohort study included 408 dialysis patients (221 males, 187 females) who underwent bioimpedance spectroscopy (BIS) and HGS assessments between March 2021 and August 2023. Data collected included BIS profiles, HGS, dialysis status, age, complete blood count, blood chemistry, mortality, and CONUT scores. Results: Cox proportional hazards regression analysis revealed that lean tissue index (LTI) (HR 3.30, 95% CI 1.75-6.19), body mass index (BMI) (HR 2.65, 95% CI 1.17-6.01), and handgrip strength (HGS) (HR 4.22, 95% CI 2.05-8.70) were significant predictors of survival in the overall dialysis patient cohort. Gender-specific analysis showed that in males, both LTI (HR 4.81, 95% CI 1.89-12.23) and HGS (HR 5.45, 95% CI 2.18-13.61) significantly predicted survival. In females, HGS (HR 6.01, 95% CI 2.42-14.94) was a significant predictor, while LTI was also significant (HR 3.22, 95% CI 1.24-8.40, p = 0.017). In the multivariate Cox proportional hazards analysis, which adjusted for age, diabetes mellitus (DM), hypertension (HTN), BMI, fat tissue index (FTI), LTI, serum albumin, C-reactive protein (CRP), and CONUT score, HGS remained a significant predictor of survival in female dialysis patients (HR 2.77, 95% CI 1.00-7.65, p = 0.049). Conclusions: HGS has been identified as an important factor for survival in dialysis patients, particularly in female patients, independent of muscle mass and BMI.

Developing a battery of physical performance tests to predict functional disability in Japanese older adults: A longitudinal study from the Kasama study

AIM

Preventing functional disability benefits the quality of life of older adults and mitigates the economic burden of an aging society. However, the most effective physical performance tests and optimal cut points for identifying older adults at risk of functional disability remain unclear, and Japan lacks physical function-based assessment tools. We aimed to identify the physical performance tests related to functional disability and to develop a predictive test battery for it.

METHODS

We included 975 older adults (mean 72.8 ± 5.2 years, 55.4% women) in Kasama City, Japan. Functional disability was defined as certification of care level 2 or above based on the long-term care insurance system. Cox proportional hazards analysis examined the association between physical performance tests and incident functional disability.

RESULTS

During a mean follow-up of 8.6 years (maximum 14 years), 236 participants (24.2%) developed functional disability. After adjusting for covariates, higher performances in grip strength, single-leg balance with eyes open (SLB), timed up-and-go (TUG), five-repetition sit-to-stand (5-STS), and 5-m habitual walk were significantly associated with a lower risk of functional disability. In a stepwise model, SLB, TUG, and 5-STS were key predictors of functional disability. Receiver operating characteristic analysis determined optimal cut points of 32.6/32.7 s for SLB, 6.5/6.6 s for TUG, and 7.8/7.9 s for 5-STS. We developed a predictive battery combining these cut points (area under the curve = 0.78).

CONCLUSIONS

The developed battery of physical performance tests predicts future functional disability and is useful for screening older adults at high risk. Geriatr Gerontol Int 2024; 24: 1343-1349.

Age-Related Influence on Static and Dynamic Balance Abilities: An Inertial Measurement Unit-Based Evaluation

Balance control, a complex sensorimotor skill, declines with age. Assessing balance is crucial for identifying fall risk and implementing interventions in the older population. This study aimed to measure age-dependent changes in static and dynamic balance using inertial measurement units in a clinical setting. This study included 82 healthy participants aged 20-85 years. For the dynamic balance test, participants stood on a horizontally swaying balance board. For the static balance test, they stood on one leg. Inertial measurement units attached to their bodies recorded kinematic data, with average absolute angular velocities assessing balance capabilities. In the dynamic test, the younger participants had smaller average absolute angular velocities in most body parts than those of the middle-aged and older groups, with no significant differences between the middle-aged and older groups. Conversely, in the single-leg stance tests, the young and middle-aged groups outperformed the older group, with no significant differences between the young and middle-aged groups. Thus, dynamic and static balance decline at different stages with age. These results highlight the complementary role of inertial measurement unit-based evaluation in understanding the effect of age on postural control mechanisms, offering valuable insights for tailoring rehabilitation protocols in clinical settings.

Severe trauma leads to sustained muscle loss, induced frailty, and distinct temporal changes in myokine and chemokine profiles of older patients

INTRODUCTION

Sarcopenia is a known risk factor for adverse outcomes across multiple disease states, including severe trauma. Factors such as age, hyperinflammation, prolonged immobilization, and critical illness may not only exacerbate progression of this disease but may also contribute to the development of induced sarcopenia, or sarcopenia secondary to hospitalization. This study seeks to (1) determine the effects of severe traumatic injury on changes in skeletal muscle mass in older adults; (2) test whether changes in skeletal muscle mass are associated with clinical frailty, physical performance, and health-related quality of life; and (3) examine trauma-induced frailty and temporal changes in myokine and chemokine profiles.

METHODS

A prospective, longitudinal cohort study of 47 critically ill, older (≥45 years) adults presenting after severe blunt trauma was conducted. Repeated measures of computed tomography-based skeletal muscle index, frailty, and quality of life were obtained in addition to selected plasma biomarkers over 6 months.

RESULTS

Severe trauma was associated with significant losses in skeletal muscle mass and increased incidence of sarcopenia from 36% at baseline to 60% at 6 months. Severe trauma also was associated with a transient worsening of induced frailty and reduced quality of life irrespective of sarcopenia status, which returned to baseline by 6 months after injury. Admission biomarker levels were not associated with skeletal muscle index at the time points studied but demonstrated distinct temporal changes across our entire cohort.

CONCLUSIONS

Severe blunt trauma in older adults is associated with increased incidence of induced sarcopenia and reversible induced frailty. Despite muscle wasting, functional decline is transient, with a return to baseline by 6 months, suggesting a need for holistic definitions of sarcopenia and further investigation into long-term functional outcomes in this population.

Muscle quality and major adverse cardiovascular events in post-acute myocardial infarction: A prospective cohort study

BACKGROUND & AIMS

Functional muscle quality, as assessed through the muscle quality index (MQI), represents a contemporary method to measure the capacity to generate force. Despite its potential, the prognostic significance of MQI remains uncertain in various clinical conditions, particularly among patients following acute myocardial infarction (AMI). In light of this, our study sought to evaluate the prognostic relevance of MQI concerning major adverse cardiovascular events (MACE) in patients following AMI.

METHODS AND RESULTS

This is a secondary analysis of a prospective cohort study that included subjects aged ≥20 years from a Cardiovascular Unit Hospital. Functional muscle quality was estimated using MQI, defined as the ratio of handgrip strength (HGS) to muscle mass (MM) derived from bioelectrical impedance analysis. The outcomes included prolonged length of hospital stay, new adverse cardiovascular events (AMI, stroke and hospital readmission for unstable angina), and cardiovascular mortality. A composite score comprising all adverse events over the 1-year follow-up was calculated and defined as MACE. This study included 163 patients, with a median age of 61 years (IQ: 54-69 years), and the majority consisted of males (76.1%). Individual components of the functional muscle quality (HGS and MM) were not associated with any of the adverse outcomes. Only MQI was associated mortality over the 1-year follow-up. For each increase in MQI, the hazard of mortality decreases: adjusted HR: 0.08 (95% CI 0.01-0.84).

CONCLUSION

Functional muscle quality assessed by the MQI may be a valuable clinical predictor of 1-year cardiovascular mortality in patients hospitalized post-AMI.

Motor function is related to the lower phase angle than to muscle mass of the lower limbs in older females with hip osteoarthritis: a cross-sectional observational study

BACKGROUND

Muscle mass and phase angle (PhA) can be measured using multi-frequency bioelectrical impedance analysis (BIA). Osteoarthritis of the hip (OAhip) causes decreased muscle mass and PhA in the deformed lower limb. However, previous studies have not accounted for the influence of sex, and thus, the relationship between muscle mass, PhA, and motor function remains unclear. This study aimed to elucidate the relationship between PhA, an index of muscle mass and quality measured using BIA, and motor function during gait and standing in female patients with OAhip.

METHODS

Muscle mass and PhA of patients with OAhip were measured using BIA. Motor function was evaluated using the Timed Up and Go test, ground reaction/weight, rate of force development/weight, and load ratio between the osteoarthritic (OA) and contralateral sides when standing up. The difference between the OA side and the contralateral lower limb was tested to clarify the characteristics of the deformed lower limb. The relationship between each motor function was determined using a partial correlation coefficient with age as a control variable and multiple regression analysis with each motor function as the dependent variable and age, OA-side muscle mass/body weight ratio, and PhA as independent variables.

RESULTS

This study involved 60 patients with OAhip (age 65.6 ± 7.6 years, height 154.2 ± 6.0 cm, weight 56.8 ± 10.5 kg) scheduled for unilateral total hip arthroplasty. Muscle mass, PhA, and lower limb load ratio were significantly decreased in the lower limbs on the OA side. Furthermore, using a partial correlation coefficient with age as a control variable, PhA showed significant correlations with motor functions related to standing up and walking, and multiple regression analysis revealed that PhA was independently related to each motor function.

CONCLUSIONS

Evaluation and interventions that consider muscle quality rather than muscle mass are important.

Functional fitness and physical independence in later years: cut-off values and validation

BACKGROUND

To establish and validate the criterion-referenced standards of functional fitness in predicting physical independence in 80 + years.

METHODS

A group of 2,749 older community dwellers (60-84 years) were recruited, and 2,050 were identified with moderate-to-high independent living ability according to the proposed minimum composite physical function score. The Senior Fitness Test battery was applied to measure functional fitness at five-year intervals. The declining rate for each fitness dimension was calculated based on the differences between any two adjacent age groups and was adjusted according to the reported degradation rate differences between the cross-sectional and longitudinal studies.

RESULTS

The age-and-sex-specific criterion-referenced standards were identified for muscle strength, cardiovascular endurance, and dynamic balance that older adults should possess at 60-79 to maintain independent living abilities. Moderate to high consistency (k = 0.622-0.650) and associations (φ = 0.641-0.694) were found between the predicted physical independence by criterion-referenced standards of functional fitness and the results from the composite physical function scale. Moreover, the predicted independent living abilities in later years from the criterion-referenced standards of functional fitness showed high test-retest reliability (Pa = 0.90-0.96).

CONCLUSION

The criterion-referenced standards for functional fitness are valid and reliable to predict independent living abilities in later years, and provide the threshold to identify the limitations in physical fitness and detect the risks of functional disabilities among older adults in an early stage.

Handgrip strength and mortality in a cohort of kidney failure patients: Comparative analysis of different normalization methods

OBJECTIVES

Reduced handgrip strength (HGS) is associated with adverse clinical outcomes. We analyzed and compared associations of HGS with mortality risk in dialysis patients, using different normalization methods of HGS.

METHODS

HGS and clinical and laboratory parameters were measured in a cohort of 446 incident dialysis patients (median age 56 y, 62% men). The area under the receiver operating characteristic curve (AUROC) was used to compare different normalization methods of HGS as predictors of mortality: absolute HGS in kilograms; HGS normalized to height, weight, or body mass index; and HGS of a reference population of sex-matched controls (percentage of the mean HGS value [HGS%]). Multivariate linear regression analysis was used to assess HGS predictors. Competing risk regression analysis was used to evaluate 5-year all-cause mortality risk. Differences in survival time between HGS% tertiles were quantitated by analyzing the restricted mean survival time.

RESULTS

The AUROC for HGS% was higher than the AUROCs for absolute or normalized HGS values. Compared with the high HGS% tertile, low HGS% (subdistribution hazard ratio [sHR] = 2.36; 95% CI, 1.19-3.70) and middle HGS% (sHR = 1.79; 95% CI, 1.12-2.74) tertiles were independently associated with higher all-cause mortality and those with high HGS% tertile survived on average 7.95 mo (95% CI, 3.61-12.28) and 18.99 mo (95% CI, 14.42-23.57) longer compared with middle and low HGS% tertile, respectively.

CONCLUSIONS

HGS% was a strong predictor of all-cause mortality risk in incident dialysis patients and a better discriminator of survival than absolute HGS or HGS normalized to body size dimensions.

Older adult driving performance assessed under simulated and on-road conditions

Simulated driving offers a convenient test of driving ability for older drivers, although the viability of using simulated driving with this population is mixed. The relative weighting of the relevant perceptual, cognitive, and physical factors may vary between simulated and on-road driving. The current study was designed to assess this possibility. We conducted simulated and on-road driving tests of 61 older adults aged 66-92 years. To ensure that the driving performance was measured similarly between the two driving modalities, we employed the Record of Driving Errors (RODE) driving assessment system during both driving tests. Correlation and random weights analysis (RWA) results indicated only modest evidence of correspondence between the simulated and on-road driving performances. The primary factors operative in both simulated and on-road driving was Useful Field of View and a measure of basic cognition. Unique factors for simulated driving included a measure of physical mobility (Time-Up-and-Go) and spatial reasoning (Line), and for on-road driving included chronological age and sensorimotor processing (Trail-Making Task A). Chronological age was correlated primarily the on-road rather than simulated test, was greatly reduced with the inclusion of additional explanatory factors, and likely reflects driving efficiency rather than driving safety. We conclude that simulated driving in healthy older drivers can be beneficial for research purposes to assess cognitive and perceptual factors that underly driving effectiveness, although it cannot serve as a clear proxy for on-road driving.

Improvement in Testosterone Production by Acorus gramineus for the Alleviation of Andropause Symptoms

Acorus gramineus has a number of beneficial effects, including protective effects against age-related disorders. In this study, the effects of A. gramineus on testosterone production and andropause symptoms were evaluated. We first treated TM3 mouse Leydig cells, responsible for testosterone production, with A. gramineus aqueous extract at different concentrations. In TM3 cells, the testosterone concentration increased in a concentration-dependent manner compared with those in the control. In addition, at 400 μg/mL extract, the mRNA expression level of the steroidogenic enzyme CYP11A1 was increased. Subsequently, 23-week-old Sprague-Dawley (SD) rats exhibiting an age-related reduction in serum testosterone (approximately 80% lower than that in 7-week-old SD rats) were administered A. gramineus aqueous extract for 8 weeks. Serum total testosterone and free testosterone levels were higher and serum estradiol, prostate-specific antigen levels, and total cholesterol levels were lower in the AG50 group (A. gramineus aqueous extract 50 mg/kg of body weight/day) than in the OLD (control group). The AG50 group also showed significant elevations in sperm count, grip strength, and mRNA expression of StAR, CYP11A1, 17β-HSD, and CYP17A1 compared with those in the OLD group. In conclusion, A. gramineus aqueous extract facilitated steroidogenesis in Leydig cells, elevated testosterone levels, lowered serum estradiol and total cholesterol levels, and increased muscle strength and sperm count, thus alleviating the symptoms of andropause. These findings suggest that A. gramineus aqueous extract is a potentially effective therapeutic agent against various symptoms associated with andropause.

Associations of muscle mass, strength, and quality with diabetes and the mediating role of inflammation in two National surveys from China and the United states

AIMS

The evidence for joint and independent associations of low muscle mass and low muscle strength with diabetes is limited and mixed. The study aimed to determine the associations of muscle parameters (muscle mass, strength, quality, and sarcopenia) and sarcopenia obesity with diabetes, and the previously unstudied mediating effect of inflammation.

MATERIALS AND METHODS

A total of 13,420 adults from the 2023 China National Health Survey (CNHS) and 5,380 adults from the 2011-2014 National Health and Nutrition Examination Survey (NHANES) were included in this study. Muscle mass was determined using bioelectrical impedance analysis (BIA) in the CNHS, and whole-body dual X-ray absorptiometry (DXA) in the NHANES. Muscle strength was assessed using digital hand dynamometer. Multivariate logistic regression models were used to evaluate the associations of muscle parameters and sarcopenia obesity with diabetes. Inflammatory status was assessed using blood cell counts and two systemic inflammation indices (platelet-to-lymphocyte ratio (PLR) and system inflammation response index (SIRI)). Mediation analysis was conducted to examine inflammation's role in these associations.

RESULTS

Low muscle mass and strength were independently related to diabetes. Low muscle quality was associated with elevated diabetes risk. Sarcopenia has a stronger association with diabetes compared to low muscle strength alone or mass alone (CNHS, odds ratio (OR) = 1.93, 95 % confidence interval (CI):1.64-2.27; NHANES, OR = 3.80, 95 %CI:2.58-5.58). Participants with sarcopenia obesity exhibit a higher risk of diabetes than those with obesity or sarcopenia alone (CNHS, OR = 2.21, 95 %CI:1.72-2.84; NHANES, OR = 6.06, 95 %CI:3.64-10.08). Associations between muscle parameters and diabetes were partially mediated by inflammation (mediation proportion: 1.99 %-36.64 %, P < 0.05).

CONCLUSION

Low muscle mass and muscle strength are independently or jointly associated with diabetes, and inflammation might be a potential mechanism underlying this association. Furthermore, the synergistic effects of sarcopenia and obesity could significantly increase diabetes risk.

Diagnostic and prognostic value of calf circumference for sarcopenia in community-dwelling older adults

BACKGROUND

An age-dependent normative values of calf circumference (CC) has been recently proposed as an accessible proxy for muscle mass. However, its usefulness to estimate sarcopenia has not been assessed. The objectives of the present study were to determine if the substitution of the classical way to assess muscle mass by these values have enough diagnostic accuracy and prognostic value among older adults living in the community.

METHODS

Data from the Toledo Study of Healthy Ageing (TSHA) were used. CC was measured using an anthropometric tape. We used two age-groups CC cut-off points: the TSHA CC median and the one proposed in the Longevity Check-up 7+ (Lookup 7+) project. Sarcopenia was defined based on the European Working Group on Sarcopenia in Older People (EWGSOP2), the Foundation for the National Institutes of Health (FNIH), and FNIH criteria standardized for our population (sFNIH). Frailty (according to the Frailty Phenotype and the Frailty Trait Scale-5) and disability (Katz index) were assessed at baseline and follow-up. Mortality and first hospitalization were also recorded. Logistic (incident frailty and worsening disability) and Cox (mortality and hospitalization) regressions were performed. Diagnostic accuracy was assessed through Kappa index, AUCs, positive and negative predictive values. Predictive ability was assessed through AUCs and integrated AUCs (IAUCs).

RESULTS

1531 participants (74.8 ± 5.8 years; 45.6% men) were included in the analysis. Prevalence rates of sarcopenia were 22.7% (sFNIH), 15.0% (FNIH), and 13.9% (EWGSOP2). Using TSHA-based cut-points of CC, the prevalence of sarcopenia was 16.8% (sFNIH), 11.0% (FNIH), and 11.5% (EWGSOP2). According to LC7+-based CC cut-off points, sarcopenia prevalence was 17.6% (sFNIH), 11.9% (FNIH), and 12.4% (EWGSOP2). CC cut-off points showed low-to-moderate agreement (Kappa Index values between 0.49 and 0.69) with appendicular lean mass for the evaluation of sarcopenia. Sarcopenia identified by Lookup 7+ and TSHA CC cut-off points was associated with the adverse events examined, with similar AUCs and IAUCs than original sarcopenia definitions, and were lost after adjustment by baseline frailty, except when the original EWGSOP2 definition was used.

CONCLUSIONS

Using normalized values of CC as a criteria of muscle mass shows moderate agreement with classical criteria for diagnosing sarcopenia and offer similar predictive value in community-dwelling older adults.

Risk of secondary sarcopenia in Europeans with fibromyalgia according to the EWGSOP2 guidelines: systematic review and meta-analysis

INTRODUCTION

Fibromyalgia is characterized by chronic widespread pain accompanied by reduced levels of physical activity and associated comorbidities such as overweight and obesity which have been associated to sarcopenia development. The aim of this systematic review is to ascertain whether Europeans with fibromyalgia show a reduction in sarcopenia determinants compared to apparently-healthy controls and to determine the risk of sarcopenia and its possible risk factors (PROSPERO: CRD42023439839).

EVIDENCE ACQUISITION

Systematic searches were conducted on six databases (Academic-Search-Ultimate, CENTRAL, PubMed, SciELO, WOS-Core Collection, and ClinicalTrials.gov last-search February-2024) looking for original studies developed in European countries which assessed any of the sarcopenia determinants proposed by the EWGSOP2-guidelines (handgrip strength, five sit-to-stand, appendicular skeletal mass [ASM], skeletal muscle index [SMI]) and included fibromyalgia and healthy-control individuals. Studies mixing fibromyalgia with other diagnoses were excluded. Random-effects meta-analyses and meta-regressions were used to analyze possible differences and associated risk factors. The risk of bias was assessed using the Cochrane-Rob tool and the Quality Assessment Tool for Observational Studies, and the certainty of the evidence using GRADE-approach.

EVIDENCE SYNTHESIS

A total of 25 studies (6393 individuals; 97% women; 20-65 years) were included. Fibromyalgia individuals showed reduced muscle strength ([handgrip] SMD: -1.16 [-1.29, -1.03]; high-certainty; [five sit-to-stand] not-assessed) and muscle quantity ([ASM] mean-difference: -0.83 kg [-1.41, -0.37]; [SMI] mean-difference: -0.26 kg/m2 [-0.41, -0.10]; both low-certainty) compared to healthy-controls. Fibromyalgia individuals had nine-times greater risk for probable sarcopenia (OR: 9.23 [6.85, 12.45]; high-certainty), but not for confirmed sarcopenia ([ASM] OR: 0.91 [0.49, 1.67]; [SMI] OR: 0.67 [0.19, 2.33]; both low-certainty) according to the EWGSOP2 cut-off points. Reduced muscle strength was strongly associated to fibromyalgia-severity (β=-0.953 [-0.069, -0.038]). Studies were rated as high-risk of bias overall because did not account for some potential confounders (physical activity, sedentary time, Body Mass Index) which could influence the estimated effect.

CONCLUSIONS

Europeans with fibromyalgia have a large reduction in muscle strength and may have a reduction in muscle quantity. The risk of probable sarcopenia according to the EWGSOP2 cut-off points was nine-times higher, but may have no difference in risk of reduced muscle quantity relative to healthy-controls. Muscle strength was strongly associated to disease severity.

Skeletal muscle dysfunction with advancing age

As a result of advances in medical treatments and associated policy over the last century, life expectancy has risen substantially and continues to increase globally. However, the disconnect between lifespan and 'health span' (the length of time spent in a healthy, disease-free state) has also increased, with skeletal muscle being a substantial contributor to this. Biological ageing is accompanied by declines in both skeletal muscle mass and function, termed sarcopenia. The mechanisms underpinning sarcopenia are multifactorial and are known to include marked alterations in muscle protein turnover and adaptations to the neural input to muscle. However, to date, the relative contribution of each factor remains largely unexplored. Specifically, muscle protein synthetic responses to key anabolic stimuli are blunted with advancing age, whilst alterations to neural components, spanning from the motor cortex and motoneuron excitability to the neuromuscular junction, may explain the greater magnitude of function losses when compared with mass. The consequences of these losses can be devastating for individuals, their support networks, and healthcare services; with clear detrimental impacts on both clinical (e.g., mortality, frailty, and post-treatment complications) and societal (e.g., independence maintenance) outcomes. Whether declines in muscle quantity and quality are an inevitable component of ageing remains to be completely understood. Nevertheless, strategies to mitigate these declines are of vital importance to improve the health span of older adults. This review aims to provide an overview of the declines in skeletal muscle mass and function with advancing age, describes the wide-ranging implications of these declines, and finally suggests strategies to mitigate them, including the merits of emerging pharmaceutical agents.

Association Between Electrical Conductivity and Global Impedance Measured by EIT with Muscle Mass Scores in Sarcopenia

Electrical impedance tomography (EIT) imaging is used for quantitative assessment of muscle mass and function in elderly with sarcopenia. However, the differences in EIT-derived parameters between patients with and without sarcopenia and the correlation between parameters and muscle function scores are unclear. Thirty-one sarcopenic and healthy subjects were recruited in this work, and maximal handgrip strength (MHG), maximal isometric voluntary contraction (MVC), and SARC-F scale of all individuals were used for muscle function scoring. The electrical conductivity and global impedance values of the gastrocnemius muscle were calculated by EIT, and then the correlation with muscle function scores was analyzed. The results showed that the mean amplitude of conductivity was ordered in the young (0.0041) > elderly (0.0034) > sarcopenia (0.0029) group, while the results for global impedance were the opposite. In addition, conductivity showed a strong positive correlation with muscle function scores (r=0.619, p<0.001), while global impedance showed a moderate negative correlation with scores (r=-0.469, p<0.05). The results demonstrate the potential of EIT imaging technology for sarcopenia diagnosis and quantitative assessment of muscle mass and function. In the future, we will expand the number of subjects, determine the independent influencing factors related to sarcopenia, and construct an accurate diagnosis and functional assessment model.

Relationship between muscle and subcutaneous adipose tissue size and density and proximal femur bone in elderly women with hip fracture

BACKGROUND

Both osteoporosis and sarcopenia are associated with aging, increasing the likelihood of falls in older adults and consequently raising the risk of hip fractures (HF).

AIMS

To explore the relationship between the size and density of muscle and subcutaneous adipose tissue (SAT) and the bone mineral density (BMD) of the proximal femur in elderly women with HF.

METHODS

Quantitative computed tomography (QCT) was conducted on the hips of 661 female participants who experienced low-energy acute HFs to measure both areal BMD (aBMD) and volume BMD (vBMD). Measurements were taken for the cross-sectional area (CSA) and density of the muscle around the hip and adjacent SAT. Multivariable linear regression models were applied to assess the relationship between these parameters.

RESULTS

Most increases in the density of the gluteus medius and minimus muscle (G.Med/MinM) were correlated with higher BMD in the femoral neck fracture (FNF) group with osteoporosis. In the FNF group, gluteus maximus muscle (G.MaxM) density was negatively associated with the BMD parameters of the proximal femur in individuals with osteoporosis, while they were positively associated with nonosteoporosis. In the intertrochanteric fracture (ITF) group without osteoporosis, both FN aBMD and FN vBMD showed significant correlations with G.Med/MinM density.

DISCUSSION

In women with HFs, bone and muscle are closely related.

CONCLUSIONS

In older women with HFs, density but not CSA of the G.Med/MinM were associated with BMD parameters of the proximal femur. Osteoporosis may influence the relationship between G.MaxM density and proximal femur BMD in elderly women with FNF.

Comparing the Impacts of Testosterone and Exercise on Lean Body Mass, Strength and Aerobic Fitness in Aging Men

BACKGROUND

Based on the largely untested premise that it is a restorative hormone that may reverse the detrimental impacts of aging, prescription of testosterone (T) has increased in recent decades despite no new clinical indications. It is apparent that middle-aged and older men with low-normal serum T levels are considering T supplementation as an anti-aging strategy. At the same time, there is evidence that physical activity (PA) is at historical lows in the Western world. In this review, we compare the impacts of T treatment aimed at achieving physiological T concentrations in middle-aged and older men, alongside the impacts of ecologically relevant forms of exercise training. The independent, and possible combined, effects of T and exercise therapy on physiological outcomes such as aerobic fitness, body composition and muscular strength are addressed.

MAIN BODY

Our findings suggest that both T treatment and exercise improve lean body mass in healthy older men. If improvement in lean body mass is the primary aim, then T treatment could be considered, and the combination of T and exercise may be more beneficial than either in isolation. In terms of muscle strength in older age, an exercise program is likely to be more beneficial than T treatment (where the dose is aimed at achieving physiological concentrations), and the addition of such T treatment does not provide further benefit beyond that of exercise alone. For aerobic fitness, T at doses aimed at achieving physiological concentrations has relatively modest impacts, particularly in comparison to exercise training, and there is limited evidence as to additive effects. Whilst higher doses of T, particularly by intramuscular injection, may have larger impacts on lean body mass and strength, this must be balanced against potential risks.

CONCLUSION

Knowing the impacts of T treatment and exercise on variables such as body composition, strength and aerobic fitness extends our understanding of the relative benefits of physiological and pharmacological interventions in aging men. Our review suggests that T has impacts on strength, body composition and aerobic fitness outcomes that are dependent upon dose, route of administration, and formulation. T treatment aimed at achieving physiological T concentrations in middle-aged and older men can improve lean body mass, whilst exercise training enhances lean body mass, aerobic fitness and strength. Men who are physically able to exercise safely should be encouraged to do so, not only in terms of building lean body mass, strength and aerobic fitness, but for the myriad health benefits that exercise training confers.

Prediction of 1-year change in knee extension strength by neuromuscular properties in older adults

Improving muscle strength and preventing muscle weakness are important for older adults. The change in strength can be effectively explained by skeletal muscle mass and neural factors. Neural factors are important for older adults because the variation of neural components is greater in older than in young adults, and any decline in strength cannot solely be explained by a decrease in skeletal muscle mass. The purpose of the present study was to investigate whether skeletal muscle mass or motor unit firing properties could explain the change in muscle strength after 1 year. Thirty-eight older adults (75.0 ± 4.7 years, 156.6 ± 7.7 cm, 55.5 ± 9.4 kg, 26 women) performed maximum voluntary knee extension and their skeletal muscle mass was measured using a bioimpedance device. During a submaximal contraction task, high-density surface electromyography was recorded and the signals were decomposed into individual motor unit firing. As an index of motor unit firing properties, the slope and y-intercept (MU intercept) were calculated from the regression line between recruitment thresholds and firing rates in each participant. After 1 year, their maximum knee extension torque was evaluated again. A stepwise multiple regression linear model with sex and age as covariates indicated that MU intercept was a significant explanation with a negative association for the 1-year change in muscle strength (β =  - 0.493, p = 0.004), but not skeletal muscle mass (p = 0.364). The results suggest that neural components might be predictors of increasing and decreasing muscle strength rather than skeletal muscle mass.

Exosomes Secreted During Myogenic Differentiation of Human Fetal Cartilage-Derived Progenitor Cells Promote Skeletal Muscle Regeneration through miR-145-5p

BACKGROUND

Currently, there is no apparent treatment for sarcopenia, which is characterized by diminished myoblast function. We aimed to manufacture exosomes that retain the myogenic differentiation capacity of human fetal cartilage-derived progenitor cells (hFCPCs) and investigate their muscle regenerative efficacy in myoblasts and a sarcopenia rat model.

METHODS

The muscle regeneration potential of exosomes (F-Exo) secreted during myogenic differentiation of hFCPCs was compared to human bone marrow mesenchymal stem cells-derived (hBMSCs) exosomes (B-Exo) in myoblasts and sarcopenia rat model. The effect of F-Exo was analyzed through known microRNAs (miRNAs) analysis. The mechanism of action of F-Exo was confirmed by measuring the expression of proteins involved in the Wnt signaling pathway.

RESULTS

F-Exo and B-Exo showed similar exosome characteristics. However, F-Exo induced the expression of muscle markers (MyoD, MyoG, and MyHC) and myotube formation in myoblasts more effectively than B-Exo. Moreover, F-Exo induced greater increases in muscle fiber cross-sectional area and muscle mass compared to B-Exo in a sarcopenia rat. The miR-145-5p, relevant to muscle regeneration, was found in high concentrations in the F-Exo, and RNase pretreatment reduced the efficacy of exosomes. The effects of F-Exo on the expression of myogenic markers in myoblasts were paralleled by the miR-145-5p mimics, while the inhibitor partially negated this effect. F-Exo was involved in the Wnt signaling pathway by enhancing the expression of Wnt5a and β-catenin.

CONCLUSION

F-Exo improved muscle regeneration by activating the Wnt signaling pathway via abundant miR-145-5p, mimicking the remarkable myogenic differentiation potential of hFCPCs.

Sex differences in skeletal muscle fiber types: A meta-analysis

Biopsies have been acquired from living men and women to determine proportions of Type I (slow-twitch) and II (fast-twitch) skeletal muscle fibers since the 1970s. Sex differences have been assumed but the literature has not been submitted to meta-analysis. Here, the aim was to generate effect sizes of sex differences in muscle fiber cross-sectional areas, distribution percentages, and area percentages. Data from 2875 men and 2452 women, who participated in 110 studies, were analyzed. Myofibrillar adenosine triphosphatase histochemistry was used in 71.8% of studies to classify fibers as Type I, II, IIA, and/or IIX; immunohistochemistry, immunofluorescence, or sodium dodecyl sulfate-polyacrylamide gel electrophoresis were used in 35.4% of studies to similarly classify myosin heavy chain (MHC) isoform content. Most studies involved biopsies from vastus lateralis (79.1%) in healthy individuals (92.7%) between 18 and 59 years old (80.9%). Men exhibited greater cross-sectional areas for all fiber types (g = 0.40-1.68); greater distribution percentages for Type II, MHC II, IIA, IIX fibers (g = 0.26-0.34); greater area percentages for Type II, IIA, MHC IIA, IIX fibers (g = 0.39-0.93); greater Type II/I and Type IIA/I fiber area ratios (g = 0.63, 0.94). Women exhibited greater Type I and MHC I distribution percentages (g = -0.13, -0.44); greater Type I and MHC I area percentages (g = -0.53, -0.69); greater Type I/II fiber area ratios (g = -1.24). These data, which represent the largest repository of comparative muscle fiber type data from living men and women, can inform discussions about biological sex and its impact on pathologies and sports performance (e.g., explaining sex differences in muscle strength and muscle endurance).

Effects of aerobic and combined aerobic-resistance exercise on motor function in sedentary older adults: A randomized clinical trial

BACKGROUND

Sedentary behavior is widespread among older adults and accelerates the decline of motor function. Nevertheless, there is insufficient evidence concerning the effectiveness of regular exercise in enhancing the same in sedentary older adults.

OBJECTIVE

To compare the effects of 24 weeks of aerobic and combined aerobic-resistance exercise on the motor function of sedentary older adults.

METHODS

Sixty healthy sedentary older (65-80 years) were randomly enrolled. Participants were randomly divided into 3 groups (1:1:1): aerobic exercise group (AEG), combined aerobic-resistance exercise group (CEG), and health education group (HEG). The training group underwent a five-day-a-week regimen, with each session lasting for 40 minutes (including 10 min warm-up and cool-down). HEG received only monthly health lectures. We assessed lower limb muscle strength (30-second sit-to-stand ability), single-dual task gait, static and dynamic balance functions at baseline and after 24 weeks of intervention using per-protocol analysis.

RESULTS

Among 60 elderly healthy who were randomized (mean age 70.59 ± 3.31 years; 28 women (46%)), 42 (70%) completed the evaluation after 24 weeks. Both the aerobic exercise and combined aerobic-resistance exercise groups exhibited improved 30-second sit-to-stand ability, static balance in closed-eye standing mode, and dynamic balance (P< 0.05). However, there were no statistically significant changes in the single-task gait parameters of stride length, stride width, and stride speed (P> 0.05). Additionally, compared to the aerobic exercise group, the combined exercise group showed an increase in dual-task gait speed and medial and lateral dynamic stability indices (P< 0.05).

CONCLUSION

Both the aerobic exercise and combined aerobic-resistance exercise programs are effective in enhancing lower limb muscle strength, dynamic balance, and static balance while standing with eyes closed in sedentary older adults. Furthermore, the combined aerobic-resistance exercise program is more effective in improving dual-task gait speed as well as medial and lateral dynamic balance.

Associations of Lower-Limb Phase Angle with Locomotion and Motor Function in Japanese Community-Dwelling Older Adults

Whole-body phase angle (PhA) is associated with motor function and geriatric diseases. However, it was unclear which parts of the upper- or lower-limb PhA were involved. This study investigated the differences in the PhA of the upper and lower extremities and their relationships with frailty, locomotive syndrome indices, and motor function in community-dwelling older adult participants. This study was a cross-sectional observational study. In 69 community-dwelling older adults, the PhA at each measurement site (whole body, upper limbs, and lower limbs), motor function, Kihon Checklist (KCL), and 25-Geriatric Locomotive Function Scale (GLFS-25) were measured. This study examined differences in each PhA and its relationship with motor function and geriatric diseases. Multiple regression analysis was performed using GLFS-25 as the dependent variable and sex and lower-limb PhA as independent variables. In this cohort (mean age: 72.3 ± 5.7 years; 18 males and 51 females), lower-limb PhA was significantly lower than upper-limb PhA. Unlike other PhAs, lower-limb PhA was related to grip strength, TUG, F/w, and GLFS-25. Multiple regression analysis showed that the lower-limb PhA was independently related to GLFS-25. Cellular health of the lower extremity is associated with gait, standing function, and indicators of locomotive syndrome.

Meta-Analysis on the Association between Echo Intensity, Muscle Strength, and Physical Function in Older Individuals

BACKGROUND

The use of ultrasonographic echo intensity (EI) to evaluate skeletal muscle quality and its effects on strength, explosive power, and physical function (PF) in older individuals remains unclear. This meta-analysis evaluated the associations among EI, muscle strength (MS), and PF in older individuals.

METHODS

We conducted a systematic search of the PubMed, Embase, Web of Science, SPORT Discus, and CINAHL databases through October 2022 to identify primary studies examining the association between EI and MS/PF. Effect sizes were computed using a random-effects model and presented using forest plots. Pearson correlation coefficient (r) and I2 statistics were used to measure heterogeneity.

RESULTS

This meta-analysis included 24 patients. EI demonstrated a negative association with maximal strength (r=-0.351; 95% confidence interval [CI], -0.411 to -0.288; p<0.001) and explosive power (r=-0.342; 95% CI, -0.517 to -0.139; p=0.001) in older individuals. Handgrip strength also showed a significant negative correlation with EI (r=-0.361; 95% CI, -0.463 to -0.249; p<0.001). However, we observed only a small and non-significant negative association between EI and gait speed (r=-0.003; 95% CI, -0.083 to -0.077; p=0.943), and a weak non-significant correlation with the chair stand test (r=0.072; 95% CI, -0.045 to 0.187; p=0.227).

CONCLUSION

Increased EI was associated with lower strength and power but not with gait speed or chair test performance in older individuals. Further large-sample studies with long-term follow-up are needed to improve frailty prediction and risk assessment in this population.

Relationship between muscle mass and muscle strength with physical performance in older adults: A systematic review

Background

Declining muscle mass is not always accompanied by declining muscle strength in older adults, challenging the notion that low muscle mass is the sole criterion for diagnosing sarcopenia.

Objective

This review aims to find out the relationships between muscle mass and muscle strength with physical performance in older adults.

Design

This article was a systematic review using Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines.

Data Sources and Methods

We do a systematic search of observational studies that are published between 2013 and August 2023 in PubMed, ScienceDirect, Sage journal, Tripdatabase, Cochrane Library, Embase, and CINAHL. Two reviewers selected and extracted data independently and an association measure was recorded from included studies.

Results

The review analyzed 17 observational studies conducted between 2013 and September 2023. The findings suggest that while declining muscle mass is often associated with sarcopenia, it may not always correspond to declining muscle strength in older individuals. The most common method used to measure muscle mass was bioelectrical impedance analysis, while handgrip strength was the predominant measure of muscle strength. Tests such as timed up and go and gait speed were used to assess physical performance.

Conclusions

Physical performance in older adults is significantly related to muscle strength, whereas the relationship between muscle mass and physical performance is either weak or negligible. Therefore, when evaluating physical performance in older individuals, focusing on muscle strength is more important than muscle mass alone.

Plasma Androstenedione Concentration Can Discriminate Frail versus Non-Frail Men with Prostate Cancer under Androgen Deprivation Therapy

BACKGROUND

Androgen deprivation therapy (ADT) is a mainstay of prostate cancer in both adjuvant and palliative settings. Since androgens are crucial for functional status and psychological functions, we evaluated whether blood testosterone, androstenedione, or DHEA concentrations were associated with functional status and psychological alterations in patients with localised (PCa) or metastatic prostate cancer (mPCa) receiving ADT with analogues of luteinising hormone-releasing hormone (LHRH).

METHODS

The five Fried criteria were considered to identify frailty syndrome. In addition, complementary evaluations were carried out to measure other variables of interest. Sleep quality was assessed using the Athens Insomnia Scale, cognitive functions were assessed using the Mini-Mental State Examination, and symptoms of depression were measured using the Yesavage Geriatric Depression Scale. Logistic regression analysis was performed to determine if the androgens level could be related to frailty syndrome, sleep impairment, depressive symptoms, and cognitive functions.

RESULTS

The results of the multivariate analyses show that high concentrations of androstenedione were significantly associated with frailty syndrome in both groups (p = 0.018; odds ratio = 4.66, 95% confidence interval [1.30-16.6]). There were significant relationships between frailty syndrome and the systemic concentration of androstenedione (p = 0.01), but not the concentration of testosterone (p = 0.60) or DHEA (p = 0.42). In addition, the results of the non-parametric tests show significant results between a decreased gait speed in the two groups (metastatic and localised) and the concentration of androstenedione (p = 0.015). High androstenedione levels were associated with a slow walking speed in the mCaP group (p = 0.016), while high testosterone levels were associated with a better walking speed in the localised CaP group (p = 0.03). For the concentration of androstenedione in plasma, the area under the curve was 0.72, with a 95% CI of 0.55-0.88 with acceptable values, and with a cut-off point of 4.51 pg/mL, a sensitivity of 82.9%, and specificity of 53.8%. No relationships between the concentration of androgens in plasma and sleep quality, cognitive functions, or symptoms of depression suggest that the changes were specific to frailty syndrome.

CONCLUSIONS

Further research into the role of androstenedione should be evaluated in follow-up studies in order to recommend its use as a suitable biomarker of frailty syndrome in prostate cancer patients.

Are sit-to-stand and isometric handgrip tests comparable assessment tools to identify dynapenia in sarcopenic people?

Sarcopenia is a neuromuscular disease characterized by the simultaneous existence of reduced muscle strength and muscle atrophy. The current recommendations for the diagnosis of sarcopenia suggest dynapenia be operationalized using either isometric handgrip strength (IHG) or sit-to-stand (STS) tests. However, specific associations between each of these assessment tools and sarcopenia-related parameters have been observed. In addition, important neuromuscular and biomechanical aspects differ between IHG and STS. This scenario has important clinical implications and calls for detailed studies to refine the current recommendations for sarcopenia identification. The present communication presents evidence to foster a constructive debate on the matter.

The association between muscle mass quantity and its quality in physically active older women

In this study, the authors aim to determine whether lower limb strength is related to lower limb lean mass and whether this relationship is affected by lower limb functionality in physically active older women. Twenty-six women underwent measures of knee muscles strength and lean mass of lower limbs. Bilateral strength of the knee flexors and extensors was measured by an isokinetic dynamometer. The concentric peak torque was measured at an angular velocity of 60°/s. Lean mass of the lower limbs was measured by bio-impedance analysis. Pearson's correlation analysis revealed significant association between the strength of the knee flexors and lean mass on non-dominant limb only (r = .427, p = .03). Researchers revealed that strategies aiming to prevent lean mass and muscle strength losses should be specifically targeted to individual muscles or muscle groups, even in physically active older women. To improve overall mobility, the strengthening of larger muscle such as hamstring is crucial.

Old muscle, new tricks: a clinician perspective on sarcopenia and where to next

PURPOSE OF REVIEW

This review offers a contemporary clinical approach to the recognition, prevention and management of sarcopenia, and discusses recent clinically relevant advances in the aetiopathogenesis of muscle ageing that may lead to future therapeutic targets.

RECENT FINDINGS

The key recent directions for sarcopenia are in the diagnosis, understanding molecular mechanisms and management. Regarding the recognition of the condition, it has become increasingly clear that different definitions hamper progress in understanding. Therefore, the Global Leadership in Sarcopenia has been established in 2022 to develop a universally accepted definition. Moreover, substantial work is occurring to understand the various roles and contribution of inflammation, oxidative stress, mitochondrial dysfunction and metabolic dysregulation on skeletal muscle function and ageing. Finally, the role of resistance-based exercise regimes has been continually emphasised. However, the role of protein supplementation and hormone replacement therapy (HRT) are still under debate, and current clinical trials are underway.

SUMMARY

With the global ageing of our population, there is increasing emphasis on maintaining good health. Maintenance of skeletal muscle strength and function are key to preventing frailty, morbidity and death.

Anabolic Resistance in the Pathogenesis of Sarcopenia in the Elderly: Role of Nutrition and Exercise in Young and Old People

The development of sarcopenia in the elderly is associated with many potential factors and/or processes that impair the renovation and maintenance of skeletal muscle mass and strength as ageing progresses. Among them, a defect by skeletal muscle to respond to anabolic stimuli is to be considered. Common anabolic stimuli/signals in skeletal muscle are hormones (insulin, growth hormones, IGF-1, androgens, and β-agonists such epinephrine), substrates (amino acids such as protein precursors on top, but also glucose and fat, as source of energy), metabolites (such as β-agonists and HMB), various biochemical/intracellular mediators), physical exercise, neurogenic and immune-modulating factors, etc. Each of them may exhibit a reduced effect upon skeletal muscle in ageing. In this article, we overview the role of anabolic signals on muscle metabolism, as well as currently available evidence of resistance, at the skeletal muscle level, to anabolic factors, from both in vitro and in vivo studies. Some indications on how to augment the effects of anabolic signals on skeletal muscle are provided.

Prevalence and risk factors of possible sarcopenia in patients with subacute stroke

Possible sarcopenia, the loss of handgrip strength in the older population, can lead to poor functional prognosis after stroke. In this retrospective study, we aimed to elucidate the clinical risk factors for possible sarcopenia at discharge in 152 hospitalized patients with subacute stroke. Univariable and multivariable logistic regression analysis was performed to determine the risk factors associated with possible sarcopenia. At the time of discharge, the prevalence of possible sarcopenia was 68.4%. After adjusting for all potential covariates, older age (odds ratio [OR], 1.10; 95% confidence interval [CI], 1.00-1.21; p = 0.04), tube-dependent feeding (OR, 6.66; 95% CI, 1.11-39.84; p = 0.04), and high National Institute of Health Stroke Scale scores (OR, 1.20; 95% CI, 1.00-1.44; p = 0.04) were associated with a higher likelihood of possible sarcopenia at discharge. Higher nonhemiplegic calf circumference (OR, 0.80; 95% CI, 0.67-0.96; p = 0.02) was associated with a lower likelihood of possible sarcopenia. We conclude that tube feeding, high stroke severity, decreased nonhemiplegic calf circumference, and older age are independent risk factors for possible sarcopenia in patients with subacute stroke.

Relationships between anthropometric and body composition characteristics and age in Polish women over 60 as affected by their socioeconomic and health status and physical activity levels

Background: Little is known about changes in anthropometric and body composition (A&BC) characteristics during the aging process. Research indicates that body composition can be linked with socioeconomic status (SES), health status (HS), and physical activity (PA) levels. Aim: The aim of this study was to evaluate age-related changes in A&BC characteristics in female seniors aged 60+ in view of their SES, HS, and PA levels. Methods: The survey was conducted in November and December 2022 on a total of 661 female seniors. A questionnaire survey was conducted to obtain information about the participants' socioeconomic status (chronic diseases, health status, marital status, membership in social organizations, financial status, place of residence, education). The respondents' PA levels were assessed with the International Physical Activity Questionnaire (IPAQ), and their A&BC characteristics were determined in a bioelectrical impedance analysis with the InBody 270 body composition analyzer. The relationships between A&BC characteristics and age were evaluated based on the values of the Pearson correlation coefficient (r). Results: The mean values of Percent Body Fat (PBF), Body Mass Index (BMI), and the waist-hip ratio (WHR) were relatively high (37.2%, 28.5 kg/m², and 0.8, respectively) and indicative of overweight and gynoid obesity. A higher number of significant negative correlations between A&BC characteristics and age were observed in seniors with lower values of SES, HS, and PA, which points to more rapid involutional changes in this group of respondents. A segmental analysis also revealed significantly lower values of fat-free mass (FFM) and body fat mass (BFM) (both indicators were calculated in percentage and kg), in particular in the upper limbs, in women with lower SES, HS, and PA levels. Conclusion: Environmental factors, including biological, physiological, environmental, psychological, behavioral, and social factors, are significantly associated with aging in women. Age-related changes in A&BC characteristics tend to proceed more rapidly in female seniors with low values of SES and HE and insufficient PA levels.

Relationship between circulating tumour DNA and skeletal muscle stores at diagnosis of pancreatic ductal adenocarcinoma: a cross-sectional study

Low skeletal muscle index (SMI) and low skeletal muscle radiodensity (SMD) are associated with reduced survival time in pancreatic ductal adenocarcinoma (PDAC). The negative prognostic impact of low SMI and low SMD is often reported as independent of cancer stage when using traditional clinical staging tools. Therefore, this study sought to explore the relationship between a novel marker of tumour burden (circulating tumour DNA) and skeletal muscle abnormalities at diagnosis of PDAC. A retrospective cross-sectional study was conducted in patients who had plasma and tumour tissue samples stored in the Victorian Pancreatic Cancer Biobank (VPCB) at diagnosis of PDAC, between 2015 and 2020. Circulating tumour DNA (ctDNA) of patients with G12 and G13 KRAS mutations was detected and quantified. Pre-treatment SMI and SMD derived from analysis of diagnostic computed tomography imaging was tested for its association to presence and concentration of ctDNA, as well as conventional staging, and demographic variables. The study included 66 patients at PDAC diagnosis; 53% female, mean age 68.7 years (SD ± 10.9). Low SMI and low SMD were present in 69.7% and 62.1% of patients, respectively. Female gender was an independent risk factor for low SMI (OR 4.38, 95% CI 1.23-15.55, p = 0.022), and older age an independent risk factor for low SMD (OR 1.066, 95% CI 1.002-1.135, p = 0.044). No association between skeletal muscle stores and concentration of ctDNA (SMI r = - 0.163, p = 0.192; SMD r = 0.097, p = 0.438) or stage of disease according to conventional clinical staging [SMI F(3, 62) = 0.886, p = 0.453; SMD F(3, 62) = 0.717, p = 0.545] was observed. These results demonstrate that low SMI and low SMD are highly prevalent at diagnosis of PDAC, and suggest they are comorbidities of cancer rather than related to the clinical stage of disease. Future studies are needed to identify the mechanisms and risk factors for low SMI and low SMD at diagnosis of PDAC to aid screening and intervention development.

The Health and Functional Benefits of Eccentric versus Concentric Exercise Training: A Systematic Review and Meta-Analysis

This review compared the effects of eccentric versus concentric exercise training in healthy people and people with metabolic disease. A systematic search on Cochrane Central Register of Controlled Trials, MEDLINE, Embase, CINAHL, SPORTDiscus, Web of Science, SCOPUS and PubMed was conducted in February 2022. Randomised controlled trials conducted on sedentary healthy adults or those with an existing metabolic disease that compared eccentric versus concentric exercise training interventions of four weeks or longer that involved multiple joints and large muscle groups (e.g., walking, whole-body resistance training) were included in the review. The primary outcome was glucose handling, measured as HbA1c, HOMA, fasting glucose or insulin. Measures of cardiovascular health, muscle strength, and functional physical fitness were secondary outcomes. Nineteen trials involving 618 people were included. Results of meta-analyses showed that eccentric exercise had no benefit to glucose handling (HbA1c level; SMD - 0.99; 95% CI, -2.96 to 0.98; n = 74; P = 0.32) but resulted in significant increases in overall muscle strength (SMD 0.70; 95% CI 0.25 to 1.15; n = 224; P = 0.003) and decreases in blood pressure (Systolic Blood Pressure; MD -6.84; 95% CI, -9.84 to -3.84; n = 47, P = 0.00001, and Diastolic Blood Pressure; MD -6.39; 95% CI -9.62 to -3.15; n = 47, P = 0.0001). Eccentric exercise is effective for improving strength and some markers of cardiovascular health compared to traditional exercise modalities. Additional high-quality studies are necessary to validate these results. (PROSPERO registration: CRD42021232167).

CT image-based biomarkers acquired by AI-based algorithms for the opportunistic prediction of falls

Objective

Evaluate whether biomarkers measured by automated artificial intelligence (AI)-based algorithms are suggestive of future fall risk.

Methods

In this retrospective age- and sex-matched case-control study, 9029 total patients underwent initial abdominal CT for a variety of indications over a 20-year interval at one institution. 3535 case patients (mean age at initial CT, 66.5 ± 9.6 years; 63.4% female) who went on to fall (mean interval to fall, 6.5 years) and 5494 controls (mean age at initial CT, 66.7 ± 9.8 years; 63.4% females; mean follow-up interval, 6.6 years) were included. Falls were identified by electronic health record review. Validated and fully automated quantitative CT algorithms for skeletal muscle, adipose tissue, and trabecular bone attenuation at the level of L1 were applied to all scans. Uni- and multivariate assessment included hazard ratios (HRs) and area under the receiver operating characteristic (AUROC) curve.

Results

Fall HRs (with 95% CI) for low muscle Hounsfield unit, high total adipose area, and low bone Hounsfield unit were 1.82 (1.65-2.00), 1.31 (1.19-1.44) and 1.91 (1.74-2.11), respectively, and the 10-year AUROC values for predicting falls were 0.619, 0.556, and 0.639, respectively. Combining all these CT biomarkers further improved the predictive value, including 10-year AUROC of 0.657.

Conclusion

Automated abdominal CT-based opportunistic measures of muscle, fat, and bone offer a novel approach to risk stratification for future falls, potentially by identifying patients with osteosarcopenic obesity.

Advances in knowledge

There are few well-established clinical tools to predict falls. We use novel AI-based body composition algorithms to leverage incidental CT data to help determine a patient's future fall risk.

Sympathetic modulation of hindlimb muscle contractility is altered in aged rats

It has recently been demonstrated that reflex excitation of muscle sympathetic nerves triggered by muscle contraction contributes to the maintenance of tetanic force (TF) in rat hindlimb muscles. We hypothesized that this feedback mechanism between the contraction of hindlimb muscles and the lumbar sympathetic nerves declines during aging. In this study, we examined the contribution of sympathetic nerves on skeletal muscle contractility in young adult (4-9 months old, n = 11) and aged (32-36 months old, n = 11) male and female rats. The tibial nerve was electrically stimulated to measure the TF of the triceps surae muscles resulting from motor nerve activation before and after cutting or stimulating (at 5-20 Hz) the lumbar sympathetic trunk (LST). The TF amplitude decreased by cutting the LST in the young and aged groups; however, the magnitude of the decrease in TF following transection of the LST in the aged rats (6.2%) was significantly (P = 0.02) smaller compared with that in the young rats (12.9%). The TF amplitude was increased by LST stimulation at ≥ 5 Hz in the young and ≥ 10 Hz in the aged groups. The overall TF response to LST stimulation was not significantly different between the two groups; however, an increase in muscle tonus resulting from LST stimulation, independent of motor nerve stimulation, was significantly (P = 0.03) greater in aged compared with young rats. The sympathetic contribution to support motor nerve-induced muscle contraction declined, whereas sympathetic-mediated muscle tonus, independent of motor nerve activity, was augmented in aged rats. These changes in sympathetic modulation of hindlimb muscle contractility may underlie the reduction of skeletal muscle strength during voluntary contraction and rigidity of motion during senescence.

The Eccentric:Concentric Strength Ratio of Human Skeletal Muscle In Vivo: Meta-analysis of the Influences of Sex, Age, Joint Action, and Velocity

For decades, researchers have observed that eccentric (ECC) muscle strength is greater than concentric (CON) muscle strength. However, knowledge of the ECC:CON strength ratio is incomplete and might inform resistance exercise prescriptions. Our purposes were to determine the magnitude of the ECC:CON ratio of human skeletal muscle in vivo and explore if sex, age, joint actions/exercises, and movement velocity impact it. A total of 340 studies were identified through searches. It was possible to analyse 1516 ECC:CON ratios, aggregated from 12,546 individuals who made up 564 groups in 335 of the identified studies. Approximately 98% of measurements occurred on isokinetic machines. Bayesian meta-analyses were performed using log-ratios as response variables then exponentiated back to raw ratios. The overall main model estimate for the ECC:CON ratio was 1.41 (95% credible interval [CI] 1.38-1.44). The ECC:CON ratio was slightly less in men (1.38 [CI 1.34-1.41]) than women (1.47 [CI 1.43-1.51]), and greater in older adults (1.62 [CI 1.57-1.68]) than younger adults (1.39 [CI 1.36-1.42]). The ratio was similar between grouped upper-body (1.42 [CI 1.38-1.46]) and lower-body joint actions/exercises (1.40 [CI 1.37-1.44]). However, heterogeneity in the ratio existed across joint actions/exercises, with point estimates ranging from 1.32 to 2.61. The ECC:CON ratio was most greatly impacted by movement velocity, with a 0.20% increase in the ratio for every 1°/s increase in velocity. The results show that ECC muscle strength is ~ 40% greater than CON muscle strength. However, the ECC:CON ratio is greatly affected by movement velocity and to lesser extents age and sex. Differences between joint actions/exercises likely exist, but more data are needed to provide more precise estimates.

Skeletal muscle aging and sarcopenia: Perspectives from mechanical studies of single permeabilized muscle fibers

The decline in muscle mass and strength with age is well documented and associated with weakness, decreased flexibility, vulnerability to diseases and/or injuries, and impaired functional restoration. The term sarcopenia has been used to refer to the loss of muscle mass, strength and impaired physical performance with advanced adult age and recently has become a major clinical entity in a super-aged society. To understand the pathophysiology and clinical manifestations of sarcopenia, it is essential to explore the age-related changes in the intrinsic properties of muscle fibers. Mechanical experiments with single muscle fibers have been conducted during the last 80 years and applied to human muscle research in the last 45 years as an in-vitro muscle function test. Fundamental active and passive mechanical properties of skeletal muscle can be evaluated using the isolated permeabilized (chemically skinned) single muscle fiber preparation. Changes in the intrinsic properties of older human single muscle fibers can be useful biomarkers of aging and sarcopenia. In this review, we summarize the historical development of single muscle fiber mechanical studies, the definition and diagnosis of muscle aging and sarcopenia, and age-related change of active and passive mechanical properties in single muscle fibers and discuss how these changes can be used to assess muscle aging and sarcopenia.