Role of the nervous system in sarcopenia and muscle atrophy with aging: strength training as a countermeasure

Home-based strength and balance exercises for fall prevention among older individuals of advanced age: a randomized controlled single-blind study

OBJECTIVE

This research was to explore the effectiveness, safety, and adherence of home-based strength and balance exercises for fall prevention among the self-reliant individuals of advanced age and analyzed the beneficial components.

METHOD

This randomized controlled single-blind study included 124 individuals aged 80 years and over(mean age 84.4±3.2 years). The test group (n=63) performed strength and balance exercises facilitated by sports video training (≥ 3 sessions a week, ≥ 30 minutes per session), while the control group (n=61) maintained their daily routines. We conducted a comprehensive geriatric assessment (self-care ability, muscle strength, mobility, cognition, and psychological status) at baseline and 12 months later and dynamic posture mapping for balance and gait.

RESULTS

The test group had a decreased risk of falls compared to the control group (25.4%vs.44.3%, respectively; RR = 0.747; 95% CI: 0.551-0.975; p = 0.027). There was no statistically significant difference in the fall rate between the two groups (0.48 falls per person-year vs. 0.67 falls per person-year, respectively; IRR: 0.708; 95% CI: 0.394-1.275; p = 0.251). The composite equilibrium score (SOTcom) for vestibular and integrated balance on the Sensory Organization Test (SOT) increased in the test group, while SOTcom decreased in the control group. In the test group, there was a significant improvement in the indexes pertaining to response time, movement speed, directional control, and endpoint offset in some directions. Adherence was better in the test group, with 54.0% exercised ≥ 3 times per week and 28.6% exercised 1-2 times per week on average.

CONCLUSION

Home-based strength and balance exercises improved balance and reduced the risk of falls among the individuals of advanced age. The video-guided, remotely monitored regimen demonstrated effectiveness, safety, and compliance, although scope for improvement remains.

Rate of force development in ankle extensors correlates with performance on functional tests that demand speed and power in older women

PURPOSE

Despite the background of decreased ankle extensor muscle strength with aging, there is still debate regarding whether the rate of force development has any relationship with musculoskeletal and functional characteristics. Therefore, we investigated the correlation between the rate of force development (RFD) in ankle extensors during heel rise (HR) and musculoskeletal characteristics and performance in functional tests in community-dwelling older women. Additionally, determine the correlation by decades of age (60-90 years).

METHODS

Correlational cross-sectional design analyzed 61 older women (72.8 ± 6.9 years, 29.4 ± 4.9 kg/m2). HR was evaluated on a force platform. In addition, anthropometric, musculoskeletal characteristics, and functional tests were measured. RFD was defined in three-time intervals (0-50 ms, 0-100 ms, and 0-peak). Peak force (Fpeak) and time to peak were also determined. Relative power-STS (STS-power), calf circumference, and skeletal muscle mass were considered musculoskeletal characteristics. Functional tests were timed up-and-go (TUG), walk speed (WS), grip strength, five sit-and-stand (5-STS), sit-and-reach, and single-leg stance.

RESULTS

The RFD and the STS-power were correlated, and the Fpeak with the musculoskeletal characteristics except with the skeletal muscle mass. RFD was correlated with the TUG, WS, and 5-STS, particularly with early RFD (0-50 ms). Oldest old women (80-90 years) only showed correlations between early RFD and the two walk-related tests (TUG and WS), compared to younger old women.

CONCLUSION

RFD during HR correlates with functional tasks involving ankle extensor's speed and power demands. Impaired RFD of ankle extensors would expose older women to more significant risks of functional loss, especially at older ages.

Association Between Reactive Strength Index and Metabolic Cost of Running in Male Master Athletes

PURPOSE

To examine the association between reactive strength index (RSI) and metabolic cost of running (MCr) in master athletes. We hypothesized that individuals with a higher RSI would exhibit a lower MCr, that both variables would be associated, and that age would moderate this relationship.

METHODS

Forty-five male master athletes participated to this study. A median split was performed to constitute 2 age groups (group 1, 47.7 [1.7] y old; group 2, 56.3 [4.6] y old). Participants underwent a single 45-minute session during which RSI was assessed with drop jumps, and MCr, during a continuous exercise of submaximal intensity performed on a treadmill.

RESULTS

A small negative association was found between net MCr and RSI in the overall sample (RSI mean r = -.38, P < .05; RSI max r = -.38, P < .05). Group 1 exhibited a lower net MCr (P < .01, d = -0.84) and higher RSI (P < .01, d > 0.82) than group 2. However, the association between the 2 measures was verified specifically in group 2 (RSI from a 20-cm drop jump, r = -.53, P < .01; RSI mean, r = -.50, P < .05; RSI maximum, r = -.57, P < .01).

CONCLUSIONS

RSI is associated with net MCR in master athletes, particularly in older participants. Additional intervention studies are now required to further explore this association.

Heavy Strength Training in Older Adults: Implications for Health, Disease and Physical Performance

Older adults typically exhibit reductions in skeletal muscle maximal strength and the ability to produce force rapidly. These reductions are often augmented by concomitant acute and chronic diseases, resulting in attenuated physical performance and higher propensity of falls and injuries. With the proportion of older adults in the population increasing, there is an alarming need for cost-effective strategies to improve physical performance and combat a multitude of age-related diseases. Surprisingly, despite convincing evidence emerging over three decades that strength training can substantially improve maximal strength (1RM), rate of force development (RFD) and power, contributing to improved health, physical performance and fall prevention, it appears that it has not fully arrived at the older adults' doorsteps. The aim of the current narrative review is to accentuate the convincing benefits of strength training in healthy and diseased older adults. As intensity appears to play a key role for improvements in 1RM, RFD and power, this review will emphasize training performed with heavy (80%-84% of 1RM) and very heavy loads (≥ 85% of 1RM), where the latter is often referred to as maximal strength training (MST). MST uses loads of ~90% of 1RM, which can only be performed a maximum of 3-5 times, 3-5 sets and maximal intentional concentric velocity. Strength training performed with loads in the heavy to very heavy domain of the spectrum may, because of the large increases in muscle strength, focuses on neural adaptations and relatively low risk, provides additional benefits for older adults and contrasts current guidelines which recommend low-to-moderate intensity (60%-70% of 1RM) and slow-moderate concentric velocity. This review also provides information on practical application of MST aimed at practitioners who are involved with preventive and/or rehabilitative health care for older adults.

Quercetin ingestion alters motor unit behavior and enhances improvement in muscle strength following resistance training in older adults: a randomized, double-blind, controlled trial

BACKGROUND

During resistance training, quercetin ingestion can enhance motor unit (MU) with a higher recruitment threshold in older adults.

OBJECTIVE

We investigated the effects of daily quercetin glucoside ingestion on chronic adaptations in muscle strength and MU behavior following resistance training in healthy older adults.

METHODS

Twenty-six older adults were randomly allocated to two groups that completed 6-week resistance training intervention with the ingestion of either placebo (PLA) or quercetin glycosides (QUE) at 200 mg/day. Maximal voluntary force (MVF) during isometric knee extension, muscle mass, and MU firing behavior during ramp task at 70%MVF were measured before (PRE) and after (POST) intervention.

RESULTS

In both groups, knee extensor MVF was significantly increased (both p < 0.001), and the improvement in QUE (115.1 ± 11.0%) was greater than in PLA (105.3 ± 4.8%) (p < 0.001) by the Mann-Whitney test. Muscle mass was not changed from PRE to POST in PLA or QUE (p > 0.050). At POST, firing rates of Mus with relatively moderate (recruited between 20 and 40%MVF) or higher (recruited between 20 and 40%MVF) recruitment thresholds were higher in QUE than PLA (p < 0.050). There was a significant correlation between %change in MVF and %change in firing rates of MUs with a relatively higher recruitment threshold from PRE to POST (p = 0.018, r = 0.642).

CONCLUSIONS

These results suggest that the adaptations of MUs with higher recruitment thresholds explain the greater improvement in muscle strength associated with QUE ingestion.

CLINICAL TRIAL REGISTRY

UMIN000053019 ( https://rctportal.niph.go.jp/detail/um?trial_id=UMIN000053019 ).

Age-related differences across the adult lifespan: a comparison of six field assessments of physical function

BACKGROUND

Age-related declines in physical capabilities often result from decreased lower-limb muscle strength and power, which are measurable through field tests. Various tests can detect functional declines in older adults, but their responsiveness to age-related differences is less understood in those without substantial impairments. Therefore, this study evaluated and compared the ability of field tests to detect age-related changes in physical and muscle function across adulthood.

METHODS

304 participants (52% female; 19-85 years) completed six field tests: handgrip strength (HGS), maximal gait speed (MGS) over a 10-m course, 5-repetition sit-to-stand power (STSP), timed up and go (TUG), countermovement jump (CMJ), and stair climbing power (SCP). Segmented regression analysis determined the relationship between age and field test performance, and identified the age at which the rate of decline increased. A multilevel linear mixed model compared decline rates between tests.

RESULTS

Before 60 years, SCP and CMJ were responsive to age-related differences (-0.70 to -0.81%/year, p < 0.05), whereas TUG and STSP (lower age-related decline, -0.18% to -0.52%/year, p < 0.05) and HGS and MGS (no significant age-related decline) exhibited lower responsiveness. After 60, most tests (except the STSP) demonstrated increased responsiveness to age-related differences, although these differences remain most pronounced in SCP and CMJ (-1.61 to -1.75%/year, p < 0.05).

CONCLUSIONS

These findings imply that most field tests are responsive to age-related declines in physical and/or muscle function after 60. In younger age groups, field tests that evaluate lower-limb power and have minimal ceiling effects, such as SCP and CMJ, should be prioritized.

Resistance exercise to reduce risk of falls in people with Alzheimer's disease: a randomised clinical trial

OBJECTIVES

To evaluate the impact of resistance exercise on the risk of falls, fear of falling, muscle strength, neuropsychiatric symptoms and ability to perform activities of daily living in people with Alzheimer's disease (AD).

DESIGN

Single-blinded randomised controlled trial.

SETTING

Five aged care centres specialising in AD, located in Andalucía, Spain.

PARTICIPANTS

Sixty people diagnosed with AD were assigned at random to either the intervention group (n = 30) or the control group (n = 30).

INTERVENTIONS

The intervention group completed three weekly resistance exercise sessions for 12 weeks, in addition to cognitive training, until completion of the study. The control group undertook cognitive training alone.

MAIN OUTCOME MEASURE

Main outcome measure: risk of falls (Short Physical Performance Battery).

SECONDARY OUTCOMES

muscle strength (hand dynamometry), neuropsychiatric symptoms (Neuropsychiatric Inventory Questionnaire), fear of falling (Activities-Specific Balance Confidence Scale) and ability to perform activities of daily living (Lawton Instrumental Activities of Daily Living Scale).

RESULTS

The analysis demonstrated differences in favour of the intervention group, in both the short and medium term, for risk of falls [post-treatment: mean difference (MD) 1.5, 95% CI of the difference 0.9 to 2.0; 3-month follow up: MD 1.1, 95% CI of the difference 0.6 to 1.6]; fear of falling (post-treatment: MD 1.5, 95% CI of the difference 4.0 to 7.7; 3-month follow up: MD 6.3, 95% CI of the difference 4.3 to 8.2); activities of daily living (post-treatment: MD 0.2, 95% CI of the difference -0.01 to 0.4; 3-month follow up: MD 0.3, 95% CI of the difference 0.01 to 0.5); neuropsychiatric symptoms (post-treatment: MD -2.2, 95% CI of the difference -3.3 to -1.0; 3-month follow up: MD -2.4, 95% CI of the difference -3.7 to -1.2); and dynamometry (post-treatment: MD 3.1, 95% CI of the difference 2.5 to 3.7; 3-month follow up: MD 2.6, 95% CI of the difference 1.9 to 3.3).

CONCLUSION

Resistance exercise effectively reduces the risk of falls, fear of falling and neuropsychiatric symptoms, and improves muscle strength in people with AD in both the short and medium term. CONTRIBUTION OF THE PAPER.

A wearable approach for Sarcopenia diagnosis using stimulated muscle contraction signal

Sarcopenia is a rapidly rising health concern in the fast-aging countries, but its demanding diagnostic process is a hurdle for making timely responses and devising active strategies. To address this, our study developed and evaluated a novel sarcopenia diagnosis system using Stimulated Muscle Contraction Signals (SMCS), aiming to facilitate rapid and accessible diagnosis in community settings. We recruited 199 adults from Wonju Severance Christian Hospital between July 2022 and October 2023. SMCS data were collected using surface electromyography sensors with the wearable device exoPill. Their skeletal muscle mass index, handgrip strength, and gait speed were also measured as the reference. Binary classification models were trained to classify each criterion for diagnosing sarcopenia based on the AWGS cutoffs. The binary classification models achieved high discriminative abilities with an AUC score near 0.9 in each criterion. When combining these criteria evaluations, the proposed sarcopenia diagnosis system performance achieved an accuracy of 89.4% in males and 92.4% in females, sensitivities of 81.3% and 87.5%, and specificities of 91.0% and 93.8%, respectively. This system significantly enhances sarcopenia diagnostics by providing a quick, reliable, and non-invasive method, suitable for broad community use. The promising result indicates that SMCS contains extensive information about the neuromuscular system, which could be crucial for understanding and managing muscle health more effectively. The potential of SMCS in remote patient care and personal health management is significant, opening new avenues for non-invasive health monitoring and proactive management of sarcopenia and potentially other neuromuscular disorders.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13534-025-00461-z.

The effects of normobaric hypoxic resistance training on muscle strength in healthy adults

Normobaric hypoxic resistance training (NHRT) has emerged as a novel approach to enhancing muscle strength, potentially offering advantages over conventional resistance training. However, its efficacy in healthy adults remains uncertain. This systematic review and meta-analysis aimed to evaluate the effects of NHRT on muscle strength indicators, including one-repetition maximum (1RM), isometric strength, and isokinetic strength, in healthy adults.

METHODS

Following PRISMA 2020 guidelines, four databases (PubMed, Web of Science, SportDiscus, and CNKI) were searched from inception to October 25, 2024, for randomized controlled trials. Study quality was assessed using the Cochrane Risk of Bias tool. Effect sizes were calculated using Review Manager 5.4.

RESULTS

A total of 22 RCTs involving 487 healthy adults were included. The meta-analysis revealed a significant small-to-moderate improvement in 1RM (SMD = 0.22, 95% CI [0.06, 0.38]) but no statistically significant effects on isometric strength (SMD = 0.32, 95% CI [-0.05, 0.70]) and isokinetic strength (SMD = 0.25, 95% CI [-0.11, 0.62]). Subgroup analyses indicated that oxygen concentrations of 14-16% and training loads of 60-80% 1RM produced the most substantial gains, particularly among untrained participants.

CONCLUSIONS

NHRT is a promising strategy for enhancing 1RM in healthy adults, with its effectiveness influenced by hypoxic levels, training load, and baseline training status. Optimal outcomes were observed at oxygen concentrations of 14-16% and moderate training loads (60-80% 1RM), particularly in untrained individuals. Further high-quality studies are warranted to confirm these outcomes and explore the underlying mechanisms.Registration number on PROSPEROCRD42024547100.

Association between sensory impairment and sarcopenia in older Chinese adults: a 4-Year longitudinal study

OBJECTIVES

Sarcopenia is a common geriatric syndrome that significantly increases the risk of falls, fractures, disability, and death in older adults. Sensory impairments are also prevalent among the elderly and may exacerbate the decline in physical function, even affecting muscle health. Understanding whether sensory impairments are risk factors affecting sarcopenia in older adults is crucial for developing effective public health policies and intervention strategies. Therefore, this study aims to explore the association between sensory impairments and sarcopenia and its components.

METHODS

This study, based on the Chinese Health and Retirement Longitudinal Study (CHARLS), included 4,195 participants aged 60 and above. The assessment of sensory impairment was based on self-reported visual and hearing capabilities. The diagnosis of sarcopenia followed the consensus of the Asian Working Group on Sarcopenia (AWGS) from 2019. Data analysis was conducted using an ordered logistic regression model, and the results report the odds ratios (ORs) and their 95% confidence intervals (CI).

RESULTS

Single sensory impairments at baseline showed no significant correlation with sarcopenia four years later, while dual sensory impairments (DSI) at baseline were significantly associated with sarcopenia (ORs: 1.308, 95% CI: 1.126-1.519). In the analysis of trends over time, transitions from no sensory impairments (NSI) to DSI (ORs: 1.372, 95% CI: 1.028-1.830), from hearing impairments (HI) to DSI (ORs: 1.334, 95% CI: 1.002-1.778), and persistent DSI (ORs: 1.470, 95% CI: 1.159-1.864) were all significantly associated with sarcopenia. Additionally, we found DSI is associated with poor physical performance and muscle mass but not muscle strength.

CONCLUSIONS

Our study indicates that DSI have a more severe impact on sarcopenia compared to single sensory impairments. Our findings offer a new perspective for prevention and intervention strategies, suggesting the inclusion of sensory impairment assessments in the clinical evaluation of sarcopenia risk. For elderly individuals with DSI, comprehensive intervention measures should be provided, such as sensory rehabilitation, nutritional support, and guidance on physical activities. For those with only a single sensory impairment, proactive preventive measures should be taken to prevent the progression to DSI.

Altered relaxation and Mitochondria-Endoplasmic Reticulum Contacts Precede Major (Mal)adaptations in Aging Skeletal Muscle and are Prevented by Exercise

Sarcopenia, or age-related muscle dysfunction, contributes to morbidity and mortality. Besides decreases in muscle force, sarcopenia is associated with atrophy and fast-to-slow fiber type switching, which is typically secondary to denervation in humans and rodents. However, very little is known about cellular changes preceding these important (mal)adaptations. To this matter, mitochondria and the sarcoplasmic reticulum are critical for tension generation in myofibers. They physically interact at the boundaries of sarcomeres forming subcellular hubs called mitochondria-endo/sarcoplasmic reticulum contacts (MERCs). Yet, whether changes at MERCs ultrastructure and proteome occur early in aging is unknown. Here, studying young adult and older mice we reveal that aging slows muscle relaxation leading to longer excitation-contraction-relaxation (ECR) cycles before maximal force decreases and fast-to-slow fiber switching takes place. We reveal that muscle MERC ultrastructure and mitochondria-associated ER membrane (MAM) protein composition are also affected early in aging and are closely associated with rate of muscle relaxation. Additionally, we demonstrate that regular exercise preserves muscle relaxation rate and MERC ultrastructure in early aging. Finally, we profile a set of muscle MAM proteins involved in energy metabolism, protein quality control, Ca2+ homeostasis, cytoskeleton integrity and redox balance that are inversely regulated early in aging and by exercise. These may represent new targets to preserve muscle function in aging individuals.

Physiological mechanisms of neuromuscular impairment in diabetes-related complications: Can physical exercise help prevent it?

Diabetes mellitus is a chronic disorder that progressively induces complications, compromising daily independence. Among these, diabetic neuropathy is particularly prevalent and contributes to substantial neuromuscular impairments in both types 1 and 2 diabetes. This condition leads to structural damage affecting both the central and peripheral nervous systems, resulting in a significant decline in sensorimotor functions. Alongside neuropathy, diabetic myopathy also contributes to muscle impairment and reduced motor performance, intensifying the neuromuscular decline. Diabetic neuropathy typically implicates neurogenic muscle atrophy, motoneuron loss and clustering of muscle fibres as a result of aberrant denervation-reinervation processes. These complications are associated with compromised neuromuscular junctions, where alterations occur in pre-synaptic vesicles, mitochondrial content and post-synaptic signalling. Neural damage is intensified by chronic hyperglycaemia and oxidative stress, exacerbating vascular dysfunction and reducing oxygen delivery. These complications imply a severe decline in neuromuscular performance, evidenced by reductions in maximal force and power output, rate of force development and muscle endurance. Furthermore, diabetes-related complications are compounded by age-related degenerative changes in long-term patients. Aerobic and resistance training offer promising approaches for managing blood glucose levels and neuromuscular function. Aerobic exercise promotes mitochondrial biogenesis and angiogenesis, supporting metabolic and cardiovascular health. Resistance training primarily enhances neural plasticity, muscle strength and hypertrophy, which are crucial factors for mitigating sarcopenia and preserving functional independence. This topical review examines current evidence on the physiological mechanisms underlying diabetic neuropathy and the potential impact of physical activity in counteracting this decline.

Alterations in neuromuscular junction morphology with ageing and endurance training modulate neuromuscular transmission and myofibre composition

Both ageing and exercise training affect the neuromuscular junction (NMJ) structure. Morphological alterations in the NMJ have been considered to influence neuromuscular transmission and myofibre properties, but the direct link between the morphology and function has yet to be established. We measured the neuromuscular transmission, myofibre composition and NMJ structure of 5-month-old (young) and 24-month-old untrained (aged control) and trained (aged trained) mice. Aged trained mice were subjected to 2 months of endurance training before the measurement. Neuromuscular transmission was evaluated in vivo as the ratio of ankle plantar flexion torque evoked by the sciatic nerve stimulation to that by direct muscle stimulation. The torque ratio was significantly lower in aged mice than in young and aged trained mice at high-frequency stimulations, showing a significant positive correlation with voluntary grip strength. The degree of pre- to post-synaptic overlap of the NMJ was also significantly lower in aged mice and positively correlated with the torque ratio. We also found that the proportion of fast-twitch fibres in the soleus muscle decreased with age, and that age-related denervation occurred preferentially in fast-twitch fibres. Age-related denervation and a shift in myofibre composition were partially prevented by endurance training. These results suggest that age-related deterioration of the NMJ structure impairs neuromuscular transmission and alters myofibre composition, but these alterations can be prevented by structural amelioration of NMJ with endurance training. Our findings highlight the importance of the NMJ as a major determinant of age-related deterioration of skeletal muscles and the clinical significance of endurance training as a countermeasure. KEY POINTS: The neuromuscular junction (NMJ) plays an essential role in neuromuscular transmission and the maintenance of myofibre properties. We show that neuromuscular transmission is impaired with ageing but recovered by endurance training, which contributes to alterations in voluntary strength. Neuromuscular transmission is associated with the degree of pre- to post-synaptic overlap of the NMJ. Age-related denervation of fast-twitch fibres and a shift in myofibre composition toward a slower phenotype are partially prevented by endurance training. Our study provides substantial evidence that age-related and exercise-induced alterations in neuromuscular transmission and myofibre properties are associated with morphological changes in the NMJ.

Age-related decline of motor unit firing rate in community-dwelling healthy older adults and daily ingestion of fish protein of Alaska pollack: a randomised trial

Neuromuscular properties decline with ageing and low-level physical activities. Alaska pollack protein (APP) is reportedly effective for improving skeletal muscular functions, even if the amount is small and exercise is not conducted. However, it is unclear whether APP intake without an exercise program affects neuromuscular dysfunction in community-dwelling adults conducting normal, everyday activities. This study aimed to investigate changes in motor unit firing properties by adding APP to daily meals in community-dwelling older adults. They were divided into an APP group or a placebo control (CON) group for randomised, double-blind treatment. Participants in APP (n = 15) and CON (n = 17) groups ingested 4.5 g/d APP and whey protein, respectively, added to daily meals for 3 months without a specific exercise intervention. High-density surface electromyography of the vastus lateralis to assess the individual motor unit firing rate during 70% of maximum voluntary ramp-up contraction (MVC), maximum knee extensor strength, muscle thickness, echo intensity, and a physical function test were evaluated at the baseline, as well as 1.5 and 3 months after the intervention. While muscle strength, muscle thickness, and motor function were not changed, the motor unit firing rate at 50%-70% of MVC showed a significant decline at 1.5 and 3 months in the CON group, but this decline was not observed in the APP group. These findings suggest that neuromuscular properties show a detectable decline on performing daily activities without a specific exercise intervention, but such a decline was not observed in the APP intake group.

Physical Inactivity and Sedentariness in Older Hearing Loss patients: Restoration With Hearing Aids

OBJECTIVES

Hearing loss causes numerous functional deficits. However, few studies have been conducted to assess the association between hearing loss and physical inactivity. This study aimed to evaluate the physical activity and sedentary behavior of hearing loss patients and their relation with the use of hearing aids.

MATERIALS AND METHODS

We extracted participants over 60 years of age with information on hearing status and physical activities from the eighth Korea National Health and Nutritional Examination Survey conducted from 2019 to 2020. We classified them into four groups: a normal hearing group (≤25 dB), a mild hearing loss group (>25 dB and ≤40 dB), a moderate hearing loss group (>40 dB and ≤50 dB), and a non-serviceable hearing group (>50 dB). Additionally, we extracted hearing aid users with hearing levels exceeding 50 dB.

RESULTS

After adjusting other factors, the non-serviceable hearing group walked less frequently than the moderate (p = 0.004) and mild hearing loss group (p < 0.001) and walked less and sat more than the normal hearing group (walking frequency: p < 0.001; walking time: p = 0.020; and sitting time: p = 0.034). Also, the hearing aid users walked more frequently (p = 0.003) and for longer (p = 0.045) than the non-serviceable hearing group.

CONCLUSION

Hearing loss is associated with reduced walking and a sedentary lifestyle. The use of hearing aids is associated with improved physical activity. Appropriate interventions, including hearing aids, should be provided to hearing loss patients.

LEVEL OF EVIDENCE

3 (individual cross-sectional study) Laryngoscope, 134:5109-5115, 2024.

Indoor air pollution by solid fuel usages for cooking is longitudinally associated with possible sarcopenia in middle-aged Chinese population

Objectives

The Asia Working Group of Sarcopenia (AWGS) 2019 consensus proposed a new concept named "possible sarcopenia". The present study was to estimate the association between indoor air pollution by solid fuel usages for cooking and possible sarcopenia among middle-aged and older Chinese population.

Methods

A longitudinal cohort analysis was carried out using nationally representative data from the China Health and Retirement Longitudinal Study (CHARLS). A total of 17,708 participants were recruited and followed up in the CHARLS. Cox proportional hazards models were used to estimate the effects of cooking fuel usages on the new onset of possible sarcopenia. Stratified analyses were performed according to gender and age, and sensitivity analyses were performed using the complete dataset.

Results

A total of 4,653 participants were included in the final cohort analysis. During the follow-up of 4 years (2011-2015), a total of 1,532 (32.92%) participants developed new-onset possible sarcopenia. Compared with clean fuel usages for cooking, solid fuel usages were associated with a higher risk of possible sarcopenia (HR = 1.37, 95% CI = 1.23-1.52, p-value < 0.001). After adjusting for potential confounders, there was a trend for association between solid fuel usages and an increased risk of possible sarcopenia. Stratified analyses by gender and age demonstrated a stronger association of the solid fuel usages with possible sarcopenia in the middle-aged female participants (Model 1: HR = 1.83, 95% CI = 1.24-2.69, p-value = 0.002; Model 2: HR = 1.65, 95% CI = 1.10-2.47, p-value = 0.016). Sensitivity analyses indicated that the results were robust.

Conclusion

Indoor air pollution from solid fuel usages for cooking was a modifiable risk factor for sarcopenia, especially in middle-aged female population. These findings provide a new prevention strategy to reduce the growing burden of sarcopenia, especially for middle-aged female individuals using solid fuels for cooking.

Mechanism-Driven Strategies for Reducing Fall Risk in the Elderly: A Multidisciplinary Review of Exercise Interventions

Falls among older adults present a major public health challenge, causing significant physical, psychological, and economic consequences. Exercise interventions are a proven strategy to reduce fall risk by targeting biomechanical, physiological, and psychological factors. This review examines evidence from 155 studies published between 2004 and 2024, including systematic reviews, meta-analyses, randomized controlled trials, and cohort studies. Data were rigorously screened and extracted using predefined criteria, with studies sourced from PubMed, MEDLINE, EBSCO (EDS), and additional gray literature identified via Google Scholar. Key findings show that balance and strength training improves postural control, gait stability, and neuromuscular coordination, while resistance training mitigates sarcopenia and enhances joint mobility. Cognitive exercises enhance attention, spatial awareness, decision-making, and psychological benefits like reduced fear of falling and greater social engagement. Multidisciplinary approaches integrating physical, cognitive, and social components deliver the most significant impact. This review underscores the value of evidence-based exercise programs in promoting active aging and enhancing the quality of life for older adults.

Muscular strength, endothelial function and cognitive disorders: state of the art

In recent years, the ageing population has increasingly grown. This process carries a range of pathophysiological changes involving alterations in the skeletal muscle, vascular endothelium and brain function, becoming an important risk factor for developing cognitive disorders and cardiovascular diseases. With ageing, there is a decrease in muscle mass and muscle strength, and a relationship between muscle strength decrease and cognitive decline has been shown. Lower handgrip strength has been linked to memory impairment, lower global cognitive function, decreased attention and reduced visuospatial abilities in the elderly, but understanding of the underlying mechanisms that explain the link between altered skeletal muscle function and structure, endothelial dysfunction, and the role of endothelial dysfunction in the onset of cognitive disorders has been scarcely explored. This review aims to detail the cellular and molecular mechanisms by which the progressive changes associated with ageing can alter healthy skeletal muscle and endothelial function, creating an environment of oxidative stress, inflammation and mitochondrial dysfunction. These changes can lead to reduced muscle strength, and the secretion of detrimental endothelial factors, resulting in endothelial dysfunction, blood-brain barrier disruption, and damage to neurons and microglia, ultimately accelerating the onset of cognitive disorders in the elderly. In addition, we aimed to describe the mechanisms that potentially explain how preserving muscular function with resistance training could prevent brain function deterioration, including the production of different factors that allow an improved endothelial function, haemodynamic parameters and brain plasticity, ultimately delaying the onset of cognitive impairment and chronic diseases.

Predicting sarcopenia in community-dwelling older adults through comprehensive physical fitness tests

BACKGROUND

Sarcopenia is typically assessed through hand grip strength, walking speed, and chair stand tests. However, it has been inadequately examined in terms of other physical fitness (PF) components in community-dwelling older adults. Thus, in this study, we explored factors influencing the risk of sarcopenia in community-dwelling older adults. In addition, we analyzed the clinicodemographic characteristics of older adults with or without sarcopenia and investigated the effect of sex on their PF.

METHODS

This cross-sectional study included 745 older adults from a community health promotion program in Taiwan. Their clinicodemographic characteristics were recorded. PF was assessed through various tests, such as hand grip strength evaluation, 8-foot up-and-go test (8-UGT), 2-min step test, and 6-m walk test. PF and factors influencing sarcopenia risk were compared between older adults with sarcopenia (sarcopenia group) and those without it (nonsarcopenia group). A logistic regression model was performed to identify key factors associated with sarcopenia. Its predictive performance was evaluated by calculating the area under the receiver operating characteristic curve (ROC) curve.

RESULTS

Regardless of sex, the sarcopenia group performed worse in almost all components of PF-for example, upper and lower limb muscular strength and endurance, cardiopulmonary fitness, and balance-than did the nonsarcopenia group. However, for men, no significant between-group difference was observed in flexibility. The logistic regression model indicated age (odds ratio [OR]: 1.107), sex (OR: 2.881), Mini Nutritional Assessment-Short Form scores (OR: 0.690), and performance in 8-UGT (OR: 1.346) as factors influencing the risk of sarcopenia. The model exhibited excellent discriminative ability in predicting sarcopenia, as indicated by an area under the curve value of 0.867 (95% confidence interval: 0.827-0.906; p < 0.05).

CONCLUSION

Older adults without sarcopenia tend to outperform those with sarcopenia in almost all PF measures, regardless of sex. Older age, male sex, low Mini Nutritional Assessment-Short Form scores, and poor performance in 8-UGT are associated with a high risk of sarcopenia.

Handgrip strength and respiratory disease mortality: Longitudinal analyses from SHARE

BACKGROUND

While the association between handgrip strength and all-cause mortality is more deeply explored, no previous studies have been specifically focused on handgrip strength and respiratory disease mortality. The purpose of the study was to investigate the association between handgrip strength and respiratory disease mortality in a large representative sample.

METHODS

Individuals aged 50 or over from 27 European countries and Israel participated in this longitudinal study. Data on handgrip strength and all-cause and respiratory disease mortality were retrieved from the Survey of Health, Ageing and Retirement in Europe (SHARE) waves 1, 2, 4, 5, 6 and 7. We estimated the sub hazard ratios (SHRs) for respiratory disease mortality using a Fine-Gray sub-distribution method with both time-varying exposure and covariates and mortality due to other causes as competing risk. Furthermore, we assessed dose-response associations of handgrip strength (modelled as a continuous exposure) with respiratory disease mortality using restricted cubic splines and estimated hazard ratios (HRs).

RESULTS

We included 60,883 men and 74,904 women with a mean age of 63.6 (SD 9.7) years at study entry. During a median (interquartile range) of 7.4 years of follow-up 565 (0.4%) participants died due to respiratory diseases. The increase of 1 single kg of handgrip strength showed a 6% incidence reduction on respiratory disease mortality (SHR, 0.94; 95%CI, 0.92-0.96) after adjusting for potential confounders. Furthermore, each kg increase of handgrip strength reduced respiratory disease mortality risk in a dose-response fashion and a significant threshold for values of 41 kg (HR, 0.49; 95%CI, 0.26-0.92) and higher was identified.

CONCLUSIONS

Higher handgrip strength is associated with lower mortality due to respiratory disease. Intervention studies are needed to determine whether strength training in respiratory disease patients can prevent premature mortality.

Exploring neuronal mechanisms of osteosarcopenia in older adults

Until recently, research on the pathogenesis and treatment of osteoporosis and sarcopenia has primarily focused on local and systemic humoral mechanisms, often overlooking neuronal mechanisms. However, there is a growing body of literature on the neuronal regulation of bone and skeletal muscle structure and function, which may provide insights into the pathogenesis of osteosarcopenia. This review aims to integrate these neuronal regulatory mechanisms to form a comprehensive understanding and inspire future research that could uncover novel strategies for preventing and treating osteosarcopenia. Specifically, the review explores the functional adaptation of weight-bearing bone to mechanical loading throughout evolutionary development, from Wolff's law and Frost's mechanostat theory to the mosaic hypothesis, which emphasizes neuronal regulation. The recently introduced bone osteoregulation reflex points to the importance of the osteocytic mechanoreceptive network as a receptor in this neuronal regulation mechanism. Finally, the review focuses on the bone myoregulation reflex, which is known as a mechanism by which bone loading regulates muscle functions neuronally. Considering the ageing-related regressive changes in the nerve fibres that provide both structural and functional regulation in bone and skeletal muscle tissue and the bone and muscle tissues they innervate, it is suggested that neuronal mechanisms might play a central role in explaining osteosarcopenia in older adults.

Resistance exercise effects on hippocampus subfield volumes and biomarkers of neuroplasticity and neuroinflammation in older adults with low and high risk of mild cognitive impairment: a randomized controlled trial

Physical exercise is suggested to promote hippocampal neuroplasticity by increasing circulating neurotrophic and anti-inflammatory factors. Our aim was to explore the interplay between the effect of progressive resistance exercise on blood biomarker levels, hippocampal neurometabolite levels and hippocampal volume in older adults with a low compared to a high risk of mild cognitive impairment (MCI). Seventy apparently healthy male/female older adults (aged 60-85 years old) were randomly allocated to a 12 week lower limb progressive resistance or no intervention, stratified for low (< 26/30) or high (≥ 26/30) Montreal Cognitive Assessment (MoCA) score, indicating MCI risk. Outcome measures were blood levels of insulin-like growth factor-1 (IGF-1), interleukin-6 (IL-6) or kynurenine (KYN); hippocampal total and subfield volumes of the cornu ammonis 1 (CA1) and 4 (CA4), subiculum, presubiculum, and dentate gyrus measured with magnetic resonance imaging (MRI); and hippocampus neurometabolites including total N-acetylaspartate (NAA), myo-inositol (mIns), and total creatine (Cr) measured with proton magnetic resonance spectroscopy (1H-MRS). We evaluated the intervention effect, cognitive status effect, their interaction and the bivariate relationship between exercise-induced changes between the outcome measures. Higher kynurenine levels (p = 0.015) and lower subiculum volumes (p = 0.043) were found in older adults with high MCI risk compared to older adults with low MCI risk. Exercise-induced CA1 volume changes were negatively correlated with hippocampal tNAA/mIns level changes (r = -0.605, p = 0.006). This study provides valuable insight in the multifactorial processes related to resistance training in older adults with low or high MCI risk.

Everyday function in schizophrenia: The impact of aerobic endurance and skeletal muscle strength

BACKGROUND

Patients with schizophrenia suffer from physical health conditions, culminating in reduced physical functioning with enormous costs for patients and society. Although aerobic endurance and skeletal muscle strength, typically reduced in this population, relate to cognition and function, no study has explored their respective contributions to performance of functional skills and everyday tasks.

METHODS

In a cross-sectional study, 48 outpatients (28/20 men/women; 35 ± 11(SD) years) with schizophrenia spectrum disorders (ICD-10; F20-25) were administered the UCSD Performance-based Skills Assessment-Brief (UPSA-B; functional skills), Specific Level of Functioning (SLOF; functional performance) and the Positive and Negative Syndrome (PANSS) scale. Peak oxygen uptake (V̇O2peak) was assessed along with leg press maximal muscle strength (1RM) and mechanical power.

RESULTS

UPSA-B performance was associated with V̇O2peak (r = 0.28,p < 0.05), accounting for 8 % (p < 0.05) of shared variance, but was unrelated to 1RM and mechanical power. The SLOF physical functioning domain was associated with V̇O2peak (r = 0.30,p < 0.05) and 1RM (r = 0.24,p < 0.05), while SLOF personal care (r = 0.27,p < 0.05) and activities (r = 0.30,p < 0.05) were related only to V̇O2peak. Hierarchical regression analyses revealed that while V̇O2peak and age combined to account for 20 % (p < 0.05) of the variance in physical functioning, the contribution of 1RM was eliminated after adjusting for age. V̇O2peak and negative symptoms combined predicted 24 % and 35 % of the variance in personal care and activities, respectively. UPSA-B scores did not add to the prediction of SLOF scores.

CONCLUSIONS

Although V̇O2peak and 1RM both relate to functional outcomes, the combination of V̇O2peak, age, and negative symptoms exert the greatest detrimental influence on functional performance beyond skills deficits.

One-week quercetin intervention modifies motor unit recruitment patterns before and during resistance exercise in older adults: A randomized controlled trial

We investigated the effects of one-week quercetin ingestion on motor unit (MU) behavior and muscle contractile properties before, during, and after a single session of resistance exercise in older adults. Twenty-four older adults were divided into two groups: those receiving quercetin glycosides (QUE) or placebo (PLA), and they performed a single session of resistance exercise. MU behavior before and during resistance exercise and electrically elicited contraction before and after resistance exercise were measured (Day 1), and the same measurements were conducted again after 7 days of placebo or quercetin glycoside ingestion (Day 8). The MU recruitment threshold (RT) was decreased (p < 0.001, 25.6 ± 10.1 to 23.6 ± 9.5 %MVC) and the exerted force normalized by the MU firing rate (FR) was increased (p = 0.003, 1.13 ± 0.24 to 1.18 ± 0.22 %MVC/pps) from Days 1 to 8, respectively, in QUE but not PLA (p = 0.263, 22.6 ± 11.9 to 21.9 ± 11.6 %MVC; p = 0.713, 1.09 ± 0.20 to 1.10 ± 0.19 %MVC/pps, respectively). On Day 1, a significant correlation between MURT and%change in MUFR from the first to last contractions during the resistance exercise was observed in both groups (QUE: p = 0.009, rs = 0.308; PLA: p < 0.001, rs = 0.403). On Day 8 %change in MUFR was negatively correlated with MURT in QUE (p = 0.044, rs = -0.251), but there was no significant correlation in PLA (p = 0.844). There was no difference in electrically elicited contraction before and after the resistance exercise between QUE and PLA (p < 0.05). These results suggest that one-week quercetin ingestion in older adults lowered MURT and led to greater fatigue in MU with higher RT than with lower RT during resistance training.

One Year of Heavy Resistance Training Modifies Muscle Fiber Characteristics in the Elderly

Physical function declines with age, accelerating during the 6th decade of life, primarily due to loss in muscle mass and strength. The present study aimed to investigate the effect of one year of heavy resistance training in older adults (62-70 years) on muscle mass and strength. Further, we investigated muscle characteristics after the intervention by obtaining muscle biopsies from the vastus lateralis to compare muscle fiber characteristics between the heavy resistance training (HRT) (n=10) and the sedentary control group (CON) (n=10). We found that one year of resistance training increased isometric muscle strength (p<0.0001, ES: 2.43 (Hedges' g)) and lean body mass (p<0.05, ES: 0.96), whereas cross-sectional area of the vastus lateralis and lean leg mass were unaltered. At year 1, the percentage of type IIX muscle fibers was lower in HRT compared to CON (p<0.05, ES: 0.99), whereas the muscle fiber size did not differ between groups for the major fiber types (I and II). In conclusion, one year of resistance training in elderly improved muscle strength and lean body mass but not cross-sectional area and lean leg mass. This indicates that the increase in muscle strength may be caused by neuromuscular adaptations rather than morphological muscle tissue changes per se.

Feasibility of Sarcopenia Diagnosis Using Stimulated Muscle Contraction Signal in Hemiplegic Stroke Patients

Sarcopenia, a condition characterized by muscle weakness and mass loss, poses significant risks of accidents and complications. Traditional diagnostic methods often rely on physical function measurements like handgrip strength which can be challenging for affected patients, including those with stroke. To address these challenges, we propose a novel sarcopenia diagnosis model utilizing stimulated muscle contraction signals captured via wearable devices. Our approach achieved impressive results, with an accuracy of 93% and 100% in sarcopenia classification for male and female stroke patients, respectively. These findings underscore the significance of our method in diagnosing sarcopenia among stroke patients, offering a non-invasive and accessible solution.

What are the temporal and physical characteristics of locally applied vibration that modulate balance in older adults? - A systematic review of the literature

BACKGROUND

Compromised balance is known to contribute to falls, which are associated with increased morbidity and mortality for older adults. Evidence suggests that the application of local vibration to the lower limbs of older adults has the potential to modulate balance.

RESEARCH QUESTION

To identify the temporal and mechanical parameters of vibration applied locally to the lower limbs of older adults that modulate measures of balance, and to define the short- and long-term effects of vibration on balance in this population.

METHODS

The PRISMA 2020 guidelines were used to conduct a systematic search including the PUBMED, EMBASE, and Scopus databases to identify peer-reviewed literature where vibration was applied to the lower limbs of older adults to modulate balance. Data was extracted using a study-specific data extraction form and risk of bias assessed. Where possible, effect sizes were calculated.

RESULTS

Of 7777 records screened, ten randomised controlled trials and 43 prospective laboratory-based studies met the inclusion criteria. Vibration frequencies ranged from 1 to 272 Hz, most studies (n=41) used ≤100 Hz. Amplitude ranged from 0.2 to 3.0 mm, most studies (n=28) used ≤1 mm. Effects of short-term vibration (applied for seconds to hours) were measured during and/or immediately after application. Short-term suprathreshold perceived muscle/tendon vibration had a 'large' destabilising effect size on balance in healthy older adults, but little or no effect on older fallers. Short-term subthreshold vibration to the soles of the feet had a 'small' stabilising effect size. Suprathreshold muscle, tendon or sole vibration applied for 10-30 min over days to weeks improved balance measures, but most (8 of 10) had increased risk of bias.

SIGNIFICANCE

The heterogeneity of methodology, populations, and vibration and balance parameters precluded conclusions about the relative effects of lower limb vibration in older adults. However, these results suggest that the application of local vibration to the lower limbs of older adults can modulate balance in the short- and long-term.

Quadriceps femoris muscle ultrasound in sarcoidosis: an observational case-control study

BACKGROUND

Although loss of muscle mass may be associated with general weakness, intolerance to physical activity and fatigue, it is underestimated and poorly understood in patients with sarcoidosis.

AIM

To compare the quadriceps femoris muscle (QFM) thickness measured by ultrasonography (US) between the female patients with sarcoidosis and controls, secondly to assess the correlation between the muscle strength, fatigue and QFM thickness.

DESIGN

Observational, case-control study.

SETTING

Physical Medicine and Rehabilitation Department of a University Hospital.

POPULATION

Thirty-one women with sarcoidosis and 27 healthy volunteers were included in the study.

METHODS

The participants were evaluated for the following outcomes: 1) handgrip strength; 2) QFM thickness measured using US; and 3) sonographic thigh adjustment ratio (STAR). The sarcoidosis group was also evaluated with the 30-second chair stand test (30s-CST) and Fatigue Severity Scale (FSS).

RESULTS

The QFM thickness and STAR values of the patients with sarcoidosis were significantly lower than those of the controls (P=0.0001). However, no statistically significant difference was observed between the handgrip strengths of the groups (P=0.581). There was no statistically significant correlation between the STAR values and handgrip strength in the sarcoidosis group; however, there was a significant positive correlation between the STAR values and 30s-CST (r=0.467, P=0.008).

CONCLUSIONS

Loss of muscle mass is one of the musculoskeletal conditions in patients with sarcoidosis that may be associated with nonspecific symptoms, such as general debility, intolerance to physical activity, and fatigue. In the present study, no difference was observed in hand grip strength between the groups, while we found that QFM thickness was affected in patients with sarcoidosis when compared to the controls. The ultrasonographic QFM evaluation seems to be an innovative tool which may be used at all stages of sarcoidosis patient follow-up.

CLINICAL REHABILITATION IMPACT

The grip strength is a commonly used test to detect muscle weakness, but onset of a decrease in muscle mass in the lower extremities may occur earlier. Considering the increased burden of musculoskeletal problems in this population, performing 30s-CST and sonographic QFM thickness is practical methods to identify risky patients.

Wearable EMG Measurement Device Using Polyurethane Foam for Motion Artifact Suppression

We propose the use of a specially designed polyurethane foam with a plateau region in its mechanical characteristics-where stress remains nearly constant during deformation-between the electromyography (EMG) electrode and clothing to suppress motion artifacts in EMG measurement. Wearable EMG devices are receiving attention for monitoring muscle weakening due to aging. However, daily EMG measurement has been challenging due to motion artifacts caused by changes in the contact pressure between the bioelectrode and the skin. Therefore, this study aims to measure EMG signals in daily movement environments by controlling the contact pressure using polyurethane foam between the bioelectrode on the clothing and the skin. Through mechanical calculations and finite element method simulations of the polyurethane foam's effect, we clarified that the characteristics of the polyurethane foam significantly influence contact pressure control and that the contact pressure is adjustable through the polyurethane foam thickness. The optimization of the design successfully controlled the contact pressure between the bioelectrode and skin from 1.0 kPa to 2.0 kPa, effectively suppressing the motion artifact in EMG measurement.

In-hospital rehabilitation with the Geriatric Activation Program Pellenberg improves functional performance in a heterogeneous geriatric population

BACKGROUND

Regaining independent living can be challenging in patients undergoing inpatient geriatric rehabilitation. Given the paucity of evidence-based physiotherapy programs for this particular heterogeneous group, the Geriatric Activation Program Pellenberg (GAPP) was developed.

PURPOSE

Investigate the evolution of functional performance, and predict detectable changes throughout 4 weeks of GAPP. Methods: Participants in this observational study (2017-2019) followed GAPP as part of their rehabilitation program. Functional balance (Berg balance scale (BBS)) and independence (Katz scale) were the primary outcomes, with gait speed, elbow and knee extension strength, cognitive processing speed, and mood as secondary outcomes. All outcomes were assessed at baseline, 2 weeks and 4 weeks later. Prediction analysis was conducted using logistic regression modeling. Previously reported minimal detectable change with 95% confidence interval (MDC95) was used as detectable change.

RESULTS

We recruited 111 participants, with 83 completing 4 weeks of GAPP and all assessments. Over 4 weeks, all outcome measures showed a significant improvement (p ≤ .007). Detectable change was found for BBS (mean improvement of 12.8 points (95% CI: 10.9-14.8), MDC95 = 6.6) and gait speed (mean improvement of 0.24 m/s (95% CI: 0.19-0.29), MDC95 = 0.1 m/s). We found that baseline scores lower than 26 on the BBS (75% sensitivity, 65% specificity) and gait speed lower than 0.34 m/s (53% sensitivity, 81% specificity) were associated with participants achieving detectable change at 4 weeks on BBS and gait speed, respectively.

CONCLUSION

Functional performance of a heterogeneous group of geriatric inpatients improved notably after 4 weeks of GAPP. Baseline scores on BBS and gait speed can partially predict detectable changes in functional performance.

Sonographic Measurements of Rectus Femoris Muscle Thickness Strongly Predict Neutropenia in Cancer Patients Receiving Chemotherapy

The objective of this study was to explore the possible association between low skeletal muscle mass (SMM)-assessed by computed tomography (CT) and ultrasound (US)-and hematologic toxicity in cancer patients. A prospective cohort study was conducted in cancer patients who received anthracycline-based chemotherapy between 2018 and 2020 and who had baseline abdominal CT including L3 level for measuring SMM. Regional muscle measurements were carried out using US. A total of 65 patients (14 males, 51 females) were included. ROC (receiver operating characteristic) analysis identified threshold values of 18.0 mm [AUC (area under the curve) = 0.765] for females and 20.0 mm (AUC = 0.813) for males, predicting severe neutropenia. Using these cut-offs, females with low rectus femoris (RF) thickness (<18.0 mm) had a significantly higher incidence of grade ≥3 neutropenia (50.0% vs. 10.8%, p = 0.005), and males with low RF values (<20.0 mm) had a higher incidence (80.0% vs. 22.2%, p = 0.063). A regression analysis, irrespective of age, gender, and body mass index, revealed that only low RF muscle thickness increased the risk of grade 3-4 neutropenia by 9.210 times (95% CI = 2.401-35.326, p = 0.001). Utilizing US to measure RF muscle thickness aids in identifying cancer patients at an elevated risk of developing neutropenia. Needless to say, US can serve as a convenient and easily accessible tool for assessing low SMM, providing repeat point-of-care evaluations in clinical practice.

Effect of advanced glycation end-products in a wide range of medical problems including COVID-19

Glycation is a physiological process that determines the aging of the organism, while in states of metabolic disorders it is significantly intensified. High concentrations of compounds such as reducing sugars or reactive aldehydes derived from lipid oxidation, occurring for example in diabetes, atherosclerosis, dyslipidemia, obesity or metabolic syndrome, lead to increased glycation of proteins, lipids and nucleic acids. The level of advanced glycation end-products (AGEs) in the body depends on rapidity of their production and the rate of their removal by the urinary system. AGEs, accumulated in the extracellular matrix of the blood vessels and other organs, cause irreversible changes in the biochemical and biomechanical properties of tissues. As a consequence, micro- and macroangiopathies appear in the system, and may contribute to the organ failure, like kidneys and heart. Elevated levels of AGEs also increase the risk of Alzheimer's disease and various cancers. In this paper, we propose a new classification due to modified amino acid residues: arginyl-AGEs, monolysyl-AGEs and lysyl-arginyl-AGEs and dilysyl-AGEs. Furthermore, we describe in detail the effect of AGEs on the pathogenesis of metabolic and old age diseases, such as diabetic complications, atherosclerosis and neurodegenerative diseases. We summarize the currently available data on the diagnostic value of AGEs and present the AGEs as a therapeutic goal in a wide range of medical problems, including SARS-CoV-2 infection and so-called long COVID.

Association between urinary glyphosate levels and hand grip strength in a representative sample of US adults: NHANES 2013-2014

Introduction

Glyphosate, a widely utilized herbicide globally, has been linked to various health issues, including cancer, birth abnormalities, and reproductive issues. Additionally, there is growing experimental support indicating potential harm to skeletal muscles. Despite this, the impact of glyphosate on human muscle health remains unclear.

Methods

We examined information gathered from the 2013-2014 National Health and Nutrition Examination Survey (NHANES), which included 1466 adults aged 18 or older. Our primary aim was to investigate the relationship between glyphosate exposure and hand grip strength, as well as its influence on lean muscle mass.

Results and discussion

Our investigation uncovered a detrimental correlation between glyphosate exposure and all measures of grip strength, except for the second test of the first hand. Specifically, we observed a statistically significant adverse association between glyphosate exposure and combined grip strength, which is calculated as the sum of the highest readings from both hands (ß coefficient of -2.000, S.E. = 0.891, p = 0.040). We did not observe a significant correlation between glyphosate levels, lean muscle mass, and the likelihood of reaching maximum grip strength meeting sarcopenia criteria. Additionally, we observed an interaction between age and glyphosate, as well as between body mass index (BMI) and glyphosate, concerning the association with combined grip strength. In this comprehensive analysis of NHANES data, our study reveals a potential association between glyphosate exposure and hand grip strength in the adult population. Our findings suggest the need for deeper exploration into the health effects of glyphosate exposure and its impact on muscle strength, shedding light on possible public health concerns.

The Effect of Web-Based Culinary Medicine to Enhance Protein Intake on Muscle Quality in Older Adults: Randomized Controlled Trial

BACKGROUND

The most common age-related musculoskeletal disorder is sarcopenia. Sarcopenia is the progressive and generalized loss of muscle mass, strength, and function. The causes of sarcopenia can include insufficient nutritional status, which may be due to protein-energy malnutrition, anorexia, limited food access and eating ability, or malabsorption. In the United States, 15.51% of older adults have been diagnosed with sarcopenia. Culinary medicine (CM) is a novel evidence-based medical field that combines the science of medicine with food and cooking to prevent and treat potential chronic diseases. CM helps individuals learn and practice culinary skills while tasting new recipes. Therefore, this program could successfully reduce barriers to protein intake, enabling older adults to enhance their diet and muscle quality.

OBJECTIVE

This study aimed to examine how a web-based CM intervention, emphasizing convenient ways to increase lean red meat intake, could improve protein intake with the promotion of physical activity to see how this intervention could affect older adults' muscle strength and mass.

METHODS

A 16-week, single-center, parallel-group, randomized controlled trial was conducted to compare a web-based CM intervention group (CMG) with a control group (CG) while monitoring each group's muscle strength, muscle mass, and physical activity for muscle quality. The CMG received weekly web-based cooking demonstrations and biweekly nutrition education videos about enhancing protein intake, whereas the CG just received the recipe handout. Anthropometrics, muscle mass, muscle strength, dietary habits, physical activity, and cooking effectiveness were established at baseline and measured after the intervention. The final number of participants for the data analysis was 24 in the CMG and 23 in the CG.

RESULTS

No between-group difference in muscle mass (P=.88) and strength (dominant P=.92 and nondominant P=.72) change from the prestudy visit was detected. No statistically significant difference in protein intake was seen between the groups (P=.50). A nonsignificant time-by-intervention interaction was observed for daily protein intake (P=.08). However, a statistically significant time effect was observed (P≤.001). Post hoc testing showed that daily protein intake was significantly higher at weeks 1 to 16 versus week 0 (P<.05). At week 16, the intake was 16.9 (95% CI 5.77-27.97) g higher than that at the prestudy visit.

CONCLUSIONS

This study did not affect protein intake and muscle quality. Insufficient consistent protein intake, low physical activity, intervention adherence, and questionnaire accuracy could explain the results. These studies could include an interdisciplinary staff, different recruitment strategies, and different muscle mass measurements. Future research is needed to determine if this intervention is sustainable in the long term and should incorporate a follow-up to determine program efficacy on several long-term behavioral and health outcomes, including if the participants can sustain their heightened protein intake and how their cooking skills have changed.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05593978; https://clinicaltrials.gov/ct2/show/NCT05593978.

Resistance exercise snacks improve muscle mass in female university employees: a prospective, controlled, intervention pilot-study

Background

Although resistance training (RT) is essential to preserve musculoskeletal fitness and maintain a healthy, independent life into old age, few women perform RT. We investigated whether resistance exercise snacking (RES) could be an efficient training approach for the workplace health promotion (WHP) to minimize barriers for participation and facilitate RT in women in order to improve musculoskeletal fitness.

Methods

This pilot-study followed a prospective, controlled intervention design. Female employees with sedentary occupations doing RT on less than 2 days/week before study participation were included. Participants self-selected for either intervention (IG) or control group (CG). While the IG [N = 15, mean age 42.1 (SD = 11.1) years] did 10 min of RES on working days for 12 weeks, the CG [N = 15, mean age 49.9 (SD = 9.7) years] was instructed to maintain their habitual physical activity. Primary endpoint was change in muscle mass. Secondary endpoint was change in maximum isometric strength. Balance, cardiovascular fitness, perceived health, and general life satisfaction was assessed for exploratory purpose. Measurements were taken before and after the intervention.

Results

12 participants of IG and 14 of CG completed the study. Muscle mass improved significantly more in the IG [+0.42 (SD = 0.54) kg] compared to the CG [-0.16 (SD = 0.51) kg] (p = 0.01, ƞ2p = 0.24). Strength did not change significantly between groups. Nevertheless, there was a trend for greater improvements in the IG compared to the CG for trunk extension, trunk flexion, and upper body push but not upper body pull. Regarding exploratory endpoints, no significant between-group changes were found. Despite their poor fitness, both groups perceived their health as good and had high life satisfaction before and after the intervention.

Conclusion

RES could be an effective approach for the WHP to promote RT in inactive women with sedentary occupations and improve their muscle mass.

The effects of 12 weeks resistance training and vitamin D administration on neuromuscular joint, muscle strength and power in postmenopausal women

BACKGROUND

This study aimed to examine the effects of 12 weeks of resistance training (RT) and vitamin D (VitD) supplementation on muscle strength and C-terminal agrin fragment (CAF) and Neurotrophin-3 (NT-3) concentrations as potential biomarkers in postmenopausal women.

METHODS

This was a randomized double-blind placebo-controlled study. Forty-four healthy postmenopausal women (55.84 ± 4.70 years and 29.61 ± 4.26 kg/m2) were randomly assigned into four groups: (1) Resistance training + placebo (RT + PLA), (2) Vitamin D supplementation (VitD), (3) Resistance training + vitamin D (RT + VitD), and (4) Placebo (PLA). VitD was supplemented as an oral capsule containing 50000 IU of cholecalciferol every two weeks. RT involved leg press, chest press, leg extension, leg curl, and shoulder press exercises, performed with 3-4 sets at 70-85 % of 1RM, three times a week.

RESULTS

Circulating levels of CAF and NT-3 did not significantly change following the intervention period in the study groups (p > 0.05). There were significant increases in upper and lower body muscle strength and power for RT + VitD and RT + PLA ( < 0.05), but not for VitD or PLA (p > 0.05). The muscle function gains for RT + VitD and RT + PLA were higher than those for VitD and PLA but did not differ between them.

CONCLUSION

12-week of RT interventions resulted in significant increases in muscle strength and power in postmenopausal women. However, VitD supplementation did not result in any additional benefits. The positive changes in muscle function promoted by RT do not seem to be associated with changes in the neuromuscular joint via the CAF or NT-3 as potential biomarkers.

Age-related changes and sex differences in ankle plantarflexion velocity

Ankle plantar flexors play a vital role in the mobility of older adults. The strength and velocity of plantarflexion are critical factors in determining walking speed. Despite reports on how age and sex affect plantarflexion strength, basic information regarding plantarflexion velocity is still lacking. This cross-sectional observational study investigated age-related changes and sex differences in plantarflexion velocity by comparing them with plantarflexion strength. A total of 550 healthy adults were classified into four age groups for each sex: Young (< 40 years old), Middle-aged (40-64 years old), Young-old (65-74 years old), and Older-old (≧ 75 years old). We measured plantarflexion velocity and strength in the long-sitting position using a gyroscope and a hand-held dynamometer, respectively. Two-way analysis of variance revealed no interaction between age and sex for either plantarflexion velocity or strength. Plantarflexion velocity exhibited a significant decline with aging, as did the plantarflexion strength. We found no significant sex differences in plantarflexion velocity in contrast to plantarflexion strength. The results indicated a significant decrease with age and no difference in plantarflexion velocity between males and females characteristic plantarflexion velocity. Understanding the characteristics of plantarflexion velocity could contribute to preventing a decline in mobility in older adults.

Effects of short-term multicomponent exercise intervention on muscle power in hospitalized older patients: A secondary analysis of a randomized clinical trial

BACKGROUND

Bed rest during hospitalization can negatively impact functional independence and clinical status of older individuals. Strategies focused on maintaining and improving muscle function may help reverse these losses. This study investigated the effects of a short-term multicomponent exercise intervention on maximal strength and muscle power in hospitalized older patients.

METHODS

This secondary analysis of a randomized clinical trial was conducted in an acute care unit in a tertiary public hospital. Ninety (39 women) older patients (mean age 87.7 ± 4.8 years) undergoing acute-care hospitalization [median (IQR) duration 8 (1.75) and 8 (3) days for intervention and control groups, respectively]) were randomly assigned to an exercise intervention group (n = 44) or a control group (n = 46). The control group received standard care hospital including physical rehabilitation as needed. The multicomponent exercise intervention was performed for 3 consecutive days during the hospitalization, consisting of individualized power training, balance, and walking exercises. Outcomes assessed at baseline and discharge were maximal strength through 1 repetition maximum test (1RM) in the leg press and bench press exercises, and muscle power output at different loads (≤30% of 1RM and between 45% and 55% of 1RM) in the leg press exercise. Mean peak power during 10 repetitions was assessed at loads between 45% and 55% of 1RM.

RESULTS

At discharge, intervention group increased 19.2 kg (Mean Δ% = 40.4%) in leg press 1RM [95% confidence interval (CI): 12.1, 26.2 kg; P < 0.001] and 2.9 kg (Mean Δ% = 19.7%) in bench press 1RM (95% CI: 0.6, 5.2 kg; P < 0.001). The intervention group also increased peak power by 18.8 W (Mean Δ% = 69.2%) (95% CI: 8.4, 29.1 W; P < 0.001) and mean propulsive power by 9.3 (Mean Δ% = 26.8%) W (95% CI: 2.5, 16.1 W; P = 0.002) at loads ≤30% of 1RM. The intervention group also increased peak power by 39.1 W (Mean Δ% = 60.0%) (95% CI: 19.2, 59.0 W; P < 0.001) and mean propulsive power by 22.9 W (Mean Δ% = 64.1%) (95% CI: 11.7, 34.1 W; P < 0.001) at loads between 45% and 55% of 1RM. Mean peak power during the 10 repetitions improved by 20.8 W (Mean Δ% = 36.4%) (95% CI: 3.0, 38.6 W; P = 0.011). No significant changes were observed in the control group for any endpoint.

CONCLUSIONS

An individualized multicomponent exercise program including progressive power training performed over 3 days markedly improved muscle strength and power in acutely hospitalized older patients.

The impact of life-long strength versus endurance training on muscle fiber morphology and phenotype composition in older men

Aging is typically associated with decreased muscle strength and rate of force development (RFD), partly explained by motor unit remodeling due to denervation, and subsequent loss of fast-twitch type II myofibers. Exercise is commonly advocated to counteract this detrimental loss. However, it is unclear how life-long strength versus endurance training may differentially affect markers of denervation and reinnervation of skeletal myofibers and, in turn, affect the proportion and morphology of fast-twitch type II musculature. Thus, we compared fiber type distribution, fiber type grouping, and the prevalence of atrophic myofibers (≤1,494 µm2) in strength-trained (OS) versus endurance-trained (OE) master athletes and compared the results to recreationally active older adults (all >70 yr, OC) and young habitually active references (<30 yr, YC). Immunofluorescent stainings were performed on biopsy samples from vastus lateralis, along with leg press maximal strength and RFD measurements. OS demonstrated similar type II fiber distribution (OS: 52.0 ± 16.4%; YC: 51.1 ± 14.4%), fiber type grouping, maximal strength (OS: 170.0 ± 18.9 kg, YC: 151.0 ± 24.4 kg), and RFD (OS: 3,993 ± 894 N·s-1, YC: 3,470 ± 1,394 N·s-1) as young, and absence of atrophic myofibers (OS: 0.2 ± 0.7%; YC: 0.1 ± 0.4%). In contrast, OE and OC exhibited more atrophic fibers (OE: 1.2 ± 1.0%; OC: 1.1 ± 1.4%), more grouped fibers, and smaller proportion of type II fibers (OE: 39.3 ± 11.9%; OC: 35.0 ± 12.4%) than OS and YC (all P < 0.05). In conclusion, strength-trained master athletes were characterized by similar muscle morphology as young, which was not the case for recreationally active or endurance-trained old. These results indicate that strength training may preserve type II fibers with advancing age in older men, likely as a result of chronic use of high contractile force generation.NEW & NOTEWORTHY Aging is associated with loss of fast-twitch type II myofibers, motor unit remodeling, and grouping of myofibers. This study reveals, for the first time, that strength training preserves neural innervation of type II fibers, resulting in similar myofiber type distribution and grouping in life-long strength-trained master athletes as young moderately active adults. In contrast, life-long endurance-trained master athletes and recreationally active old adults demonstrated higher proportion of type I fibers accompanied by more marked grouping of type I myofibers, and more atrophic fibers compared with strength-trained master athletes and young individuals. Thus, strength training should be utilized as a training modality for preservation of fast-twitch musculature, maximal muscle strength, and rapid force capacity (RFD) with advancing age.

Hallmarks of ageing in human skeletal muscle and implications for understanding the pathophysiology of sarcopenia in women and men

Ageing is a complex biological process associated with increased morbidity and mortality. Nine classic, interdependent hallmarks of ageing have been proposed involving genetic and biochemical pathways that collectively influence ageing trajectories and susceptibility to pathology in humans. Ageing skeletal muscle undergoes profound morphological and physiological changes associated with loss of strength, mass, and function, a condition known as sarcopenia. The aetiology of sarcopenia is complex and whilst research in this area is growing rapidly, there is a relative paucity of human studies, particularly in older women. Here, we evaluate how the nine classic hallmarks of ageing: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication contribute to skeletal muscle ageing and the pathophysiology of sarcopenia. We also highlight five novel hallmarks of particular significance to skeletal muscle ageing: inflammation, neural dysfunction, extracellular matrix dysfunction, reduced vascular perfusion, and ionic dyshomeostasis, and discuss how the classic and novel hallmarks are interconnected. Their clinical relevance and translational potential are also considered.

Disuse-induced muscle fibrosis, cellular senescence, and senescence-associated secretory phenotype in older adults are alleviated during re-ambulation with metformin pre-treatment

Muscle inflammation and fibrosis underlie disuse-related complications and may contribute to impaired muscle recovery in aging. Cellular senescence is an emerging link between inflammation, extracellular matrix (ECM) remodeling and poor muscle recovery after disuse. In rodents, metformin has been shown to prevent cellular senescence/senescent associated secretory phenotype (SASP), inflammation, and fibrosis making it a potentially practical therapeutic solution. Thus, the purpose of this study was to determine in older adults if metformin monotherapy during bed rest could reduce muscle fibrosis and cellular senescence/SASP during the re-ambulation period. A two-arm controlled trial was utilized in healthy male and female older adults (n = 20; BMI: <30, age: 60 years+) randomized into either placebo or metformin treatment during a two-week run-in and 5 days of bedrest followed by metformin withdrawal during 7 days of recovery. We found that metformin-treated individuals had less type-I myofiber atrophy during disuse, reduced pro-inflammatory transcriptional profiles, and lower muscle collagen deposition during recovery. Collagen content and myofiber size corresponded to reduced whole muscle cellular senescence and SASP markers. Moreover, metformin treatment reduced primary muscle resident fibro-adipogenic progenitors (FAPs) senescent markers and promoted a shift in fibroblast fate to be less myofibroblast-like. Together, these results suggest that metformin pre-treatment improved ECM remodeling after disuse in older adults by possibly altering cellular senescence and SASP in skeletal muscle and in FAPs.

Hormonal, immune, and oxidative stress responses to blood flow-restricted exercise

INTRODUCTION

Heavy-load free-flow resistance exercise (HL-FFRE) is a widely used training modality. Recently, low-load blood-flow restricted resistance exercise (LL-BFRRE) has gained attention in both athletic and clinical settings as an alternative when conventional HL-FFRE is contraindicated or not tolerated. LL-BFRRE has been shown to result in physiological adaptations in muscle and connective tissue that are comparable to those induced by HL-FFRE. The underlying mechanisms remain unclear; however, evidence suggests that LL-BFRRE involves elevated metabolic stress compared to conventional free-flow resistance exercise (FFRE).

AIM

The aim was to evaluate the initial (<10 min post-exercise), intermediate (10-20 min), and late (>30 min) hormonal, immune, and oxidative stress responses observed following acute sessions of LL-BFRRE compared to FFRE in healthy adults.

METHODS

A systematic literature search of randomized and non-randomized studies was conducted in PubMed, Embase, Cochrane Central, CINAHL, and SPORTDiscus. The Cochrane Risk of Bias (RoB2, ROBINS-1) and TESTEX were used to evaluate risk of bias and study quality. Data extractions were based on mean change within groups.

RESULTS

A total of 12525 hits were identified, of which 29 articles were included. LL-BFRRE demonstrated greater acute increases in growth hormone responses when compared to overall FFRE at intermediate (SMD 2.04; 95% CI 0.87, 3.22) and late (SMD 2.64; 95% CI 1.13, 4.16) post-exercise phases. LL-BFRRE also demonstrated greater increase in testosterone responses compared to late LL-FFRE.

CONCLUSION

These results indicate that LL-BFRRE can induce increased or similar hormone and immune responses compared to LL-FFRE and HL-FFRE along with attenuated oxidative stress responses compared to HL-FFRE.

Association between the 110-kDa C-terminal agrin fragment and skeletal muscle decline among community-dwelling older women

BACKGROUND

C-terminal agrin fragment (CAF) is a biomarker for neuromuscular junction degradation. This study aimed to investigate whether 110-kDa CAF (CAF110) was associated with the presence and incidence of low muscle mass and strength.

METHODS

This cross-sectional retrospective cohort study comprised women aged ≥65 years. We measured muscle mass using a dual-energy X-ray absorptiometry scanner, hand-grip strength, and blood sampling between 2011 and 2012. A follow-up study with the same measurements was conducted between 2015 and 2017. Low muscle mass and strength were defined as an appendicular skeletal muscle mass index <5.4 kg/m2 and hand-grip strength <18 kg, respectively. The CAF110 level was measured using enzyme-linked immunosorbent assay kits.

RESULTS

In total, 515 women (74.3 ± 6.3 years) were included in this cross-sectional analysis. Of these, 101 (19.6%) and 128 (24.9%) women presented with low muscle mass and strength, respectively. For low muscle mass, the odds ratios (ORs) of the middle and highest CAF110 tertile groups, compared with the lowest group, were 1.93 (95% confidence interval: 1.09-3.43; P = 0.024) and 2.15 (1.22-3.80; P = 0.008), respectively. After adjusting for age, the ORs remained significant: 1.98 (1.11-3.52; P = 0.020) and 2.27 (1.28-4.03; P = 0.005), respectively. Low muscle strength ORs of all the CAF110 tertile groups were not significant. In the longitudinal analysis, 292 and 289 women were assessed for incidents of low muscle mass and strength, respectively. Of those, 34 (11.6%) and 20 (6.9%) women exhibited low muscle mass and strength, respectively. For incident low muscle mass, the crude OR of the CAF110 ≥ the median value group was marginally higher than that of the CAF110 < median value group (median [interquartile range]: 1.98 [0.94-4.17] (P = 0.072). After adjusting for age and baseline muscle mass, the OR was 2.22 [0.97-5.06] (P = 0.058). All low muscle strength ORs of the median categories of CAF110 were not significant.

CONCLUSIONS

CAF110 was not associated with low muscle strength. However, CAF110 may be a potential marker for the incidence of low muscle mass.

Elevated biomarkers of neural injury in older adults following head-down bed rest: links to cardio-postural deconditioning with spaceflight and aging

Introduction

Prolonged physical inactivity with bed rest or spaceflight is associated with cardiovascular and neuromuscular deconditioning; however, its impact on neural integrity of cardio-postural reflexes and possible mitigation with exercise has not been examined. We assessed the association between the physiological deconditioning of bed rest immobilization with neural injury markers and the effects of 60-75 min of daily exercise.

Methods

Data were collected as part of a randomized clinical trial (clinicaltrials.gov identifier: NCT04964999) at the McGill University Medical Centre. Twenty-two 55- to 65-year-old healthy volunteers gave informed consent and took part. Within sex, participants were randomly assigned to exercise (60- to 75-min daily) or control (inactive) groups and spent 14 days in continuous 6° head-down tilt. Neural injury [neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), total tau (t-Tau), myelin basic protein (MBP), brain-derived neurotrophic factor (BDNF), ubiquitin carboxy-terminal hydrolase L1 (UCH-L1)], as well as interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and insulin-like growth factor 1 (IGF-1) biomarkers were measured before, during, and after bed rest. The false discovery rate with Huber M-estimation was used to correlate changes in biomarkers with cardiovascular and muscular function changes over bed rest.

Results

Bed rest elevated NfL, GFAP, TNF-α, and IL-6 in all participants and reduced IGF-1 in females only. With standing, changes in heart rate, blood pressure, and lower limb muscle motoneuron activity correlated with changes in TNF-α and BDNF. Baroreflex control, leg muscle maximal voluntary contraction, and postural sway are correlated with GFAP and NfL. Exercise participants had fewer interactions than control participants, but significant correlations still existed, with both groups exhibiting similar reductions in orthostatic tolerance.

Discussion

An hour of daily exercise in older persons otherwise immobilized for 2 weeks did not abate bed rest-induced increases in serum signatures of neural injury or pro-inflammatory markers. Exercise reduced the number of physiological interactions of biomarkers, but significant cardio-postural correlations remained with no protection against post-bed rest orthostatic intolerance. The identification of associations of inflammatory and neural injury biomarkers with changes in cardio-postural physiology and exercise points to biotherapeutic opportunities and improved exercise interventions for astronauts and individuals in bed rest.

Clinical trial registration

https://www.clinicaltrials.gov/search?cond=NCT04964999, identifier: NCT04964999.

Emergence and Progression of Behavioral Motor Deficits and Skeletal Muscle Atrophy across the Adult Lifespan of the Rat

The facultative loss of muscle mass and function during aging (sarcopenia) poses a serious threat to our independence and health. When activities of daily living are impaired (clinical phase), it appears that the processes leading to sarcopenia have been ongoing in humans for decades (preclinical phase). Here, we examined the natural history of sarcopenia in male outbred rats to compare the occurrence of motor behavioral deficits with the degree of muscle wasting and to explore the muscle-associated processes of the preclinical and clinical phases, respectively. Selected metrics were validated in female rats. We used the soleus muscle because of its long duty cycles and its importance in postural control. Results show that gait and coordination remain intact through middle age (40-60% of median lifespan) when muscle mass is largely preserved relative to body weight. However, the muscle shows numerous signs of remodeling with a shift in myofiber-type composition toward type I. As fiber-type prevalence shifted, fiber-type clustering also increased. The number of hybrid fibers, myofibers with central nuclei, and fibers expressing embryonic myosin increased from being barely detectable to a significant number (5-10%) at late middle age. In parallel, TGFβ1, Smad3, FBXO32, and MuRF1 mRNAs increased. In early (25-month-old) and advanced (30-month-old) aging, gait and coordination deteriorate with the progressive loss of muscle mass. In late middle age and early aging due to type II atrophy (>50%) followed by type I atrophy (>50%), the number of myofibers did not correlate with this process. In advanced age, atrophy is accompanied by a decrease in SCs and βCatenin mRNA, whereas several previously upregulated transcripts were downregulated. The re-expression of embryonic myosin in myofibers and the upregulation of mRNAs encoding the γ-subunit of the nicotinic acetylcholine receptor, the neuronal cell adhesion molecule, and myogenin that begins in late middle age suggest that one mechanism driving sarcopenia is the disruption of neuromuscular connectivity. We conclude that sarcopenia in rats, as in humans, has a long preclinical phase in which muscle undergoes extensive remodeling to maintain muscle mass and function. At later time points, these adaptive mechanisms fail, and sarcopenia becomes clinically manifest.

Study protocol of a cluster-randomised controlled trial assessing a multimodal machine-based exercise training programme in senior care facilities over 6 months - the bestform study (best function of range of motion)

BACKGROUND

Physical functioning is a crucial factor for independence and quality of life in old age. The aim of the "bestform-Best function of range of motion" trial is to investigate the effects of a 6 months multimodal machine-based strength, coordination and endurance training on physical function, risk of falls and health parameters in older adults.

METHODS

Bestform is a cluster-randomised trial including older adults  ≥ 65 years living in senior care facilities in Southern Germany. Senior care facilities are randomly allocated to the control group with usual care (n ≥ 10 care facilities) and to the intervention group (n ≥ 10 care facilities), overall including  ≥ 400 seniors. Residents belonging to the intervention group are offered a supervised machine-based exercise training programme twice weekly over 45-60 min over six months in small groups, while those in the usual care facilities will not receive active intervention. The primary outcome is the change in Short Physical Performance Battery over six months between groups. Secondary outcomes are change in risk of falling, fear of falling, number of falls and fall-related injuries, physical exercise capacity, handgrip strength, body composition, cardiac function, blood parameters, quality of life, risk of sarcopenia, activities of daily living, and cognition over three and six months.

DISCUSSION

The bestform study investigates the change in physical function between seniors performing exercise intervention versus usual care over six months. The results of the study will contribute to the development of effective physical activity concepts in senior care facilities.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT04207307. Registered December 2019.

Effects of exercise therapy on disability, mobility, and quality of life in the elderly with chronic low back pain: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Exercise is an effective treatment in chronic low back pain (CLBP), but there are few studies on CLBP in the elderly, and the intervention effect is controversial. We aimed to compare the efficacy of different exercises therapy on CLBP, dysfunction, quality of life, and mobility in the elderly.

METHODS

We searched Web of Science, MEDLINE, Cochrane Library, Chinese National Knowledge Infrastructure, EMBASE, and PubMed from the database inception till December 31, 2022. The publication languages were Chinese and English. Randomized controlled trials (RCTs) of exercise intervention in the elderly (≥ 60 years) with CLBP were included. Two reviewers independently extracted the data and evaluated them using the Revised Cochrane Risk of Bias Tool for Randomized Trials 2 (RoB2). The pooled effect sizes on different aspects of outcome measures were calculated.

RESULTS

Sixteen articles (18 RCTs) were included, comprising a total of 989 participants. The quality of included studies was relatively high. Meta-analysis results indicated that exercise therapy could improve visual analog scale (VAS) (WMD = - 1.75, 95% CI - 2.59, - 0.92, p < 0.05), Oswestry disability index (ODI) (WMD = - 9.42, 95% CI - 15.04, - 3.79, p < 0,005), short-form 36-item health survey physical composite summary (SF-36PCS) (WMD = 7.07, 95% CI 1.01, 13.14, p < 0.05), short-form 36-item health survey mental composite summary (SF-36MCS) (WMD = 7.88, 95% CI 0.09, 15.67, p < 0.05), and timed up and go test (TUG) (WMD = - 0.92, 95% CI - 2.22, 0.38, p < 0.005).

CONCLUSION

Exercise therapy effectively improved VAS, ODI, and SF-36 indexes in the elderly. Based on the subgroup, when designing the exercise therapy regimen, aerobics, strength, and mind-body exercise (≥ 12 weeks, ≥ 3 times/week, ≥ 60 min) should be considered carefully, to ensure the safety and effectiveness for the rehabilitation of CLBP patients. More high-quality trials are needed in future to confirm the effect of exercise on SF-36 and TUG indexes.

Age-related gene expression signatures from limb skeletal muscles and the diaphragm in mice and rats reveal common and species-specific changes

BACKGROUND

As a result of aging, skeletal muscle undergoes atrophy and a decrease in function. This age-related skeletal muscle weakness is known as "sarcopenia". Sarcopenia is part of the frailty observed in humans. In order to discover treatments for sarcopenia, it is necessary to determine appropriate preclinical models and the genes and signaling pathways that change with age in these models.

METHODS AND RESULTS

To understand the changes in gene expression that occur as a result of aging in skeletal muscles, we generated a multi-time-point gene expression signature throughout the lifespan of mice and rats, as these are the most commonly used species in preclinical research and intervention testing. Gastrocnemius, tibialis anterior, soleus, and diaphragm muscles from male and female C57Bl/6J mice and male Sprague Dawley rats were analyzed at ages 6, 12, 18, 21, 24, and 27 months, plus an additional 9-month group was used for rats. More age-related genes were identified in rat skeletal muscles compared with mice; this was consistent with the finding that rat muscles undergo more robust age-related decline in mass. In both species, pathways associated with innate immunity and inflammation linearly increased with age. Pathways linked with extracellular matrix remodeling were also universally downregulated. Interestingly, late downregulated pathways were exclusively found in the rat limb muscles and these were linked to metabolism and mitochondrial respiration; this was not seen in the mouse.

CONCLUSIONS

This extensive, side-by-side transcriptomic profiling shows that the skeletal muscle in rats is impacted more by aging compared with mice, and the pattern of decline in the rat may be more representative of the human. The observed changes point to potential therapeutic interventions to avoid age-related decline in skeletal muscle function.

Unraveling age-related impairment of the neuromuscular system: exploring biomechanical and neurophysiological perspectives

With extended life expectancy, the quality of life of elders is a priority. Loss of mobility, increased morbidity and risks of falls have dramatic individual and societal impacts. Here we consider the age-related modifications of gait, from a biomechanical and neurophysiological perspective. Among the many factors of frailty involved (e.g., metabolic, hormonal, immunological), loss of muscle strength and neurodegenerative changes inducing slower muscle contraction may play a key role. We highlight that the impact of the multifactorial age-related changes in the neuromuscular systems results in common features of gait in the immature gait of infants and older adults. Besides, we also consider the reversibility of age-related neuromuscular deterioration by, on the one hand, exercise training, and the other hand, novel techniques such as direct spinal stimulation (tsDCS).

A Narrative Review of Non-Pharmacological Strategies for Managing Sarcopenia in Older Adults with Cardiovascular and Metabolic Diseases

This narrative review examines the mechanisms underlying the development of cardiovascular disease (CVD) and metabolic diseases (MDs), along with their association with sarcopenia. Furthermore, non-pharmacological interventions to address sarcopenia in patients with these conditions are suggested. The significance of combined training in managing metabolic disease and secondary sarcopenia in type II diabetes mellitus is emphasized. Additionally, the potential benefits of resistance and aerobic training are explored. This review emphasises the role of nutrition in addressing sarcopenia in patients with CVD or MDs, focusing on strategies such as optimising protein intake, promoting plant-based protein sources, incorporating antioxidant-rich foods and omega-3 fatty acids and ensuring sufficient vitamin D levels. Moreover, the potential benefits of targeting gut microbiota through probiotics and prebiotic fibres in sarcopenic individuals are considered. Multidisciplinary approaches that integrate behavioural science are explored to enhance the uptake and sustainability of behaviour-based sarcopenia interventions. Future research should prioritise high-quality randomized controlled trials to refine exercise and nutritional interventions and investigate the incorporation of behavioural science into routine practices. Ultimately, a comprehensive and multifaceted approach is essential to improve health outcomes, well-being and quality of life in older adults with sarcopenia and coexisting cardiovascular and metabolic diseases.