Skeletal muscle performance and ageing

Higher dietary fibre intake is associated with increased skeletal muscle mass and strength in adults aged 40 years and older

BACKGROUND

Skeletal muscle mass begins to decline from 40 years of age. Limited data suggest that dietary fibre may modify lean body mass (BM), of which skeletal muscle is the largest and most malleable component. We investigated the relationship between dietary fibre intake, skeletal muscle mass and associated metabolic and functional parameters in adults aged 40 years and older.

METHODS

We analysed cross-sectional data from the US National Health and Nutrition Examination Survey between 2011 and 2018 from adults aged 40 years and older. Covariate-adjusted multiple linear regression analyses were used to evaluate the association between dietary fibre intake and BM components (BM, body mass index [BMI], total lean mass, appendicular lean mass, bone mineral content, total fat, trunk fat; n = 6454), glucose homeostasis (fasting glucose, fasting insulin, HOMA2-IR; n = 5032) and skeletal muscle strength (combined grip strength; n = 5326). BM components and skeletal muscle strength were expressed relative to BM (per kg of BM).

RESULTS

Higher intakes of dietary fibre were significantly associated with increased relative total lean mass (β: 0.69 g/kg BM; 95% CI, 0.48-0.89 g/kg BM; P < 0.001), relative appendicular lean mass (β: 0.34 g/kg BM; 95% CI, 0.23-0.45 g/kg BM; P < 0.001), relative bone mineral content (β: 0.05 g/kg BM; 95% CI, 0.02-0.07 g/kg BM; P < 0.001) and relative combined grip strength (β: 0.002 kg/kg BM; 95% CI, 0.001-0.003 kg/kg BM; P < 0.001). Conversely, higher dietary fibre intakes were significantly associated with a lower BM (β: -0.20; 95% CI, -0.28 to -0.11 kg; P < 0.001), BMI (β: -0.08 kg/m² ; 95%CI, -0.10 to -0.05 kg/m² ), relative total fat (β: -0.68 g/kg BM; 95% CI, -0.89 to -0.47 g/kg BM; P < 0.001), relative trunk fat (β: -0.48 g/kg BM; 95%CI, -0.63 to -0.33 g/kg; P < 0.001), fasting glucose (β: -0.01 mmol/L; 95% CI, -0.02 to -0.00 mmol/L; P = 0.017), fasting insulin (β: -0.71 pmol/L; 95% CI, -1.01 to -0.41 pmol/L; P < 0.001) and HOMA2-IR (β: -0.02 AU; 95% CI, -0.02 to -0.01 AU; P < 0.001).

CONCLUSIONS

Higher dietary fibre intakes are associated with a lower BM and enhanced body composition, characterized by a reduction in fat mass and an increase in lean mass. Higher dietary fibre intakes were also associated with improvements in glucose homeostasis and skeletal muscle strength. Increasing dietary fibre intake may be a viable strategy to prevent age-associated declines in skeletal muscle mass.

Isometric Strength Database for Muscle Maximal Voluntary Endurance Field Tests: Normative Data

Background

Different field tests are used to evaluate muscle capacity, in particular maximal voluntary isometric endurance. However, although there are some normative values for a few muscle endurance tests, these do not consider the weight, height, gender, or age of individuals, which are well-known factors that influence muscle performance.

Hypothesis/Purpose

The purpose of this study was to investigate the test–retest reproducibility of eight field tests and establish muscle endurance norms, in a healthy population, based on their anthropometric characteristics, which could allow the optimal evaluation of the entire muscle function in a quick manner.

Design

Case series.

Methods

This study was conducted in two phases. The first phase was to check the reproducibility inter- and intra-assessor for eight isometric muscle field tests on 20 volunteer subjects aged 40.9 ± 11.6 years old (age range, 21–58 years). The second part was to establish muscle maximal voluntary isometric endurance norms according to these tests on a total of 400 healthy participants grouped by age (50 males and females in each of the age brackets, 20–29; 30–39; 40–49; 50–59 years old, for a total of 200 males and 200 females).

Results

The intra- and inter-assessor reproducibility tests are good for all muscle measurements (the intraclass correlation coefficients varied between 0.915 and 0.996 and the coefficient of variation between 3.6 and 11.8%). The area under the receiver operating characteristic curves demonstrates a good sensibility with values greater than 0.7 for each test. Each muscle belt presents same ratio regardless of the age and gender group. The simultaneous multiple regression analyses highlight that the anthropometric characteristics of subjects influence significantly the performance of isometric tests.

Conclusion

This study has permitted establishing prediction equations in a healthy population according to their anthropometric characteristics as well as agonist/antagonist ratios for eight muscle isometric field tests after demonstrating a good reproducibility of all tests.

Impact of regional white matter hyperintensities on specific gait function in Alzheimer's disease and mild cognitive impairment

BACKGROUND

Gait disturbance and musculoskeletal changes are evident in persons living with Alzheimer's disease (AD). Because complex gait control requires the integration of neural networks, cerebral small vessel disease (SVD), which is highly prevalent in persons with AD, might have an additional impact on gait disturbance. This study investigated whether white matter hyperintensities (WMH) are more predominantly associated with gait disturbance in persons with AD than in individuals with mild cognitive impairment (MCI) and normal cognition (NC) and further identified the regional impact of WMH on specific gait changes.

METHODS

This study included 396 subjects (aged 65 to 86 years, 63.9% female) diagnosed with AD (n = 187), MCI (n = 118), or NC (n = 91). WMH, lacunes, perivascular spaces, and cerebral microbleeds were assessed as markers of SVD. The volume of WMH was quantified in each brain lobe (frontal, temporal, occipital, and parietal) and sublobar regions in the basal ganglia and thalamus. Gait function was assessed using an electronic walkway. We investigated the association between regional WMH and gait disturbance in individuals with AD, MCI, and NC, adjusted for classical and musculoskeletal confounders.

RESULTS

Among markers of SVD, WMH were most associated with gait disturbance. In AD subjects, periventricular WMH in the frontal and parietal lobes were associated with slow gait speed (r_s  = -0.21, P = 0.007 and r_s  = -0.18, P = 0.019, respectively). These lesions were also associated with changes in stride time, double-leg support time, and walking angle (all r_s  > 0.20, P < 0.01). Lesions in the basal ganglia and thalamus were associated with slow gait speed (r_s  = -0.16, P = 0.034 and r_s  = -0.18, P = 0.023, respectively) and greater gait speed variability (r_s  = 0.16, P = 0.034 and r_s  = 0.20, P = 0.010, respectively). MCI subjects showed only associations between sublobar lesions and shorter stride length (r_s  = -0.24, P = 0.016) and increased walking angle (r_s  = 0.32, P = 0.002). NC subjects did not show associations between WMH and gait parameters. MCI and NC subjects were more affected by muscle weakness than WMH for global gait function (r_s  = 0.42, P < 0.001 and r_s  = 0.23, P = 0.046, respectively).

CONCLUSIONS

Persons with AD showed a predominant association between WMH and gait disturbance compared with MCI and NC subjects, and regional WMH had a detrimental effect on specific gait changes.

Leucine-enriched whey protein supplementation, resistance-based exercise, and cardiometabolic health in older adults: a randomized controlled trial

BACKGROUND

Increasing protein intake (above the Recommended Dietary Amount) alone or with resistance-based exercise is suggested to improve cardiometabolic health; however, randomized controlled trials (RCTs) are needed to confirm this.

METHODS

The Liverpool Hope University-Sarcopenia Aging Trial (LHU-SAT) was a 16 week RCT (ClinicalTrials.gov Identifier: NCT02912130) of 100 community-dwelling older adults [mean age: 68.73 ± 5.80 years, body mass index: 27.06 ± 5.18 kg/m² (52% women)] who were randomized to four independent groups [Control (C), Exercise (E), Exercise + Protein (EP), Protein (P)]. E and EP completed supervised and progressive resistance-based exercise (resistance exercise: two times per week, functional circuit exercise: once per week), while EP and P were supplemented with a leucine-enriched whey protein drink (three times per day) based on individual body weight (0.50 g/kg/meal, 1.50 g/kg/day). Outcome measures including arterial stiffness (pulse wave velocity), fasting plasma/serum biomarkers [glucose/glycated haemoglobin, total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein, insulin, resistin, leptin, adiponectin, C-reactive protein, tumour necrosis factor-alpha, interleukin-6, cystatin-C, & ferritin], insulin resistance (HOMA-IR), and kidney function (eGFR) were measured before and after intervention.

RESULTS

Total protein intake (habitual diet plus supplementation) increased to 1.55 ± 0.69 g/kg/day in EP and to 1.93 ± 0.72 g/kg/day in P, and remained significantly lower (P < 0.001) in unsupplemented groups (E: 1.08 ± 0.33 g/kg/day, C: 1.00 ± 0.26 g/kg/day). At 16 weeks, there was a group-by-time interaction whereby absolute changes in LDL-cholesterol were lower in EP [mean difference: -0.79 mmol/L, 95% confidence interval (CI): -1.29, -0.28, P = 0.002] and P (mean difference: -0.76 mmol/L, 95% CI: -1.26, -0.26, P = 0.003) vs. C. Serum insulin also showed group-by-time interactions at 16 weeks whereby fold changes were lower in EP (mean difference: -0.40, 95% CI: -0.65, -0.16, P = 0.001) and P (mean difference: -0.32, 95% CI: -0.56, -0.08, P = 0.009) vs. C, and fold changes in HOMA-IR improved in EP (mean difference: -0.37, 95% CI: -0.64, -0.10, P = 0.007) and P (mean difference: -0.27, 95% CI: -0.53, -0.00, P = 0.048) vs. C. Serum resistin declined in P only (group-by-time interaction at 16 weeks: P = 0.009). No other interactions were observed in outcome measures (P > 0.05), and kidney function (eGFR) remained unaltered.

CONCLUSIONS

Sixteen weeks of leucine-enriched whey protein supplementation alone and combined with resistance-based exercise improved cardiometabolic health markers in older adults.

Dance and Music for Improving Health among Patients with Breast Cancer and Parkinson’s Disease: A Narrative Review

Although a longer life may bring new opportunities for older people and society, advancing age is a leading risk factor for developing several chronic diseases, consequently limiting the health span. During the ageing process, changes in the activity of several endocrine glands may occur, leading to different clinical conditions. Being physically active becomes fundamental for healthy ageing. Despite regular physical activity being shown to have many health benefits, patients with cancer and neurodegenerative diseases remain physically inactive. Over the past two decades, there has been a major increase in arts engagement (e.g., dance and music) on health and well-being in both clinical and non-clinical contexts. Dance and music have been shown to induce positive effects on hormonal glands, patients’ sociality, and self-confidence. Therefore, this review aims to highlight evidence regarding the effects of music and dance on hormonal responses and as preventive and compliance tools for heathy ageing in breast cancer and Parkinson’s disease patients.

Effects of vibrotactile-enhanced music-based intervention on sensorimotor control capacity in the hand of an aging brain: a pilot feasibility randomized crossover trial

BACKGROUND

Music-based interventions (MBI), using music as a therapeutic medium, has been utilized as a promising strategy for motor relearning and shaping. However, currently, MBI with active performance training is restricted to being extensively applied for patients with various levels of defects in fine motor skills and cognitive functions. Therefore, the integration of vibrotactile stimulation with MBI has been adopted as a motor training strategy intended to enhance motor learning through use of vibration stimuli. The current study was designed to investigate differences in the sensorimotor performance of older adults' hands under baseline, a single session of active MBI, and vibrotactile-enriched MBI conditions.

METHODS

Thirty healthy older adults were recruited and randomized to receive either the single session of 30-min of vibrotactile-enriched MBI or 30-min of active MBI at the beginning of the experiment. After a one-week washout period, they switched their treatment programs and then were assessed to study the training effects of both approaches through measuring precision pinch performance, hand function, and sensory status.

RESULTS

The results of the Pinch-Holding-Up Activity test revealed a statistically significant difference in the FRpeak parameter (F = 14.37, p < 0.001, η2p = 0.507) under the vibrotactile-enriched MBI condition compared to the baseline and active MBI conditions. In addition, significant beneficial effects were found on the results of the barognosis (F = 19.126, p < 0.001, η2p = 0. 577) and roughness differentiation subtests (F = 15.036, p < 0.001, η2p = 0.518) in the Manual Tactile Test for the participants in the vibrotactile-enriched MBI group. In addition, the participants under both the active MBI and vibrotactile-enriched MBI conditions exhibited better performance in the three subtests of the Purdue Pegboard Test as compared to under the baseline condition (p < 0.016).

CONCLUSIONS

The findings indicated that vibrotactile-enriched MBI potentially improves the precision pinch performance of hands in healthy older adults. In addition, the add-on effect of vibrotactile stimulation to the MBI condition provides beneficial effects on the sensory functions of the upper extremities.

TRIAL REGISTRATION

NCT04802564 . Date of registration: 15/03/2021. The first posted date: 17/03/2021.

Association between biomarkers of bone health and osteosarcopenia among Iranian older people: The Bushehr Elderly Health (BEH) program

Background

Osteosarcopenia is referred to as co-incidence of osteoporosis/osteopenia and sarcopenia which is defined as a geriatric syndrome with a significant prevalence that increases morbidity and mortality. There are some relevant factors that can show an increased risk of incidence of osteosarcopenia.

Aim

We aimed to consider the association of bone turnover markers such as Osteocalcin (OC), C-terminal cross-linked telopeptide (CTX), Tartrate Resistant acid Phosphatase (TRAP), Bone Alkaline Phosphatase (BALP) and also other factors like vitamin D, calcium, phosphorous, and ALP with osteosarcopenia in elderly.

Methods

We carried out a cross-sectional study on a random sample including 400 elder participants of Bushehr Elderly Health (BEH) study, in Iran. Osteopenia/ osteoporosis was defined as a T-score ≤ -1.0 standard deviation below the mean values of a young healthy adult. We defined sarcopenia as low muscle strength (handgrip strength<26 kg for men and <18 kg for women) with reduced skeletal muscle mass [Skeletal muscle index (SMI) < 7.0 kg/m² for male and <5.4 kg/m² for female]. Osteosarcopenia was considered as the presence of both osteopenia/osteoporosis and sarcopenia. We estimated the age-standardized prevalence of osteosarcopenia for men and women, separately. We used multivariable logistic regression to address the factors associated with osteosarcopenia.

Results

The results showed that there was a statistically significant difference in OC), CTX, TRAP were between the osteosarcopenia (-) and osteosarcopenia (+) groups. No statistically significant difference was observed in BALP, vitamin D, calcium, phosphorous, and ALP between the compared groups.

In the multivariable logistic regression model, OC and CTX were associated with increased likelihood of osteosarcopenia [adjusted OR= 1.023(1.002-1.045 for OC, 4.363(1.389-15.474 for CTX)]. Furthermore, TRAP increases the odds of osteosarcopenia in crude model [OR= 1.333 (1.070- 1.660)].

Conclusions

We observed the association between bone turnover markers particularly OC, CTX and osteosarcopenia. Given the rapid growth of the aging population, we should focus on geriatric diseases such as musculoskeletal disorders. Bone turnover markers maybe improve the early diagnosis, screening and assess the response to therapies in people with osteosarcopenia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02608-w.

The effects of supervision on three different exercises modalities (supervised vs. home vs. supervised+home) in older adults: Randomized controlled trial protocol

BACKGROUND

Multicomponent physical exercise programs are a viable strategy for treating physical decline resulting from the aging process in older populations and can be applied in supervised and home-based modalities. However, the magnitude of the intervention effects in terms of physical function development may vary according to the modalities application due to different supervision degrees.

OBJECTIVE

This study aims to compare the effects of supervision in a multicomponent exercise program in different application modalities (supervised vs. home vs. supervised+home) in neuromuscular adaptations, muscle strength, gait, physical function, and quality of life, analyzing the differences between intensity, volume, and density of home and supervised sessions in community older adults.

METHODS

This protocol is a randomized controlled clinical trial with a sample of 66 older adults divided into three groups: supervised exercise (SUP = 22), home-based exercise (HB = 22), and supervised plus home-based exercise (SUP+HB = 22). The multicomponent exercise program will last 12 weeks, three times per week, for 60 min per session and include warm-up, balance, muscle-strengthening, gait, and flexibility exercises. The study's primary outcomes will be neuromuscular function, composed of the assessment of muscle isokinetic strength, muscle architecture, and neuromuscular electrical activation. The secondary outcome will be physical function, usual and maximum gait speed with and without dual-task, and quality of life. All outcomes will be assessed at baseline and post-intervention (week 12).

CONCLUSION

This study will be the first clinical trial to examine the effects of different supervision levels on home-based exercises compared to supervised protocols. The results of this study will be essentials for planning coherent and viable home-based programs for older adults.

TRIAL REGISTRATION

Brazilian Registry of Clinical Trials. Number RBR- 7MZ2KR. https://apps.who.int/trialsearch/Trial2.aspx?TrialID=RBR-7mz2kr.

The relationships between step count and hospitalisation-associated outcomes in acutely hospitalised older adults - A systematic review

BACKGROUND AND PURPOSE

Although low ambulation among older adults has been linked to a broad range of adverse outcomes during and after acute hospitalisation, a systematic inquiry of the link between step count and these consequences is required. Therefore, the main purpose of this study is to systematically review the relationships between step count and hospitalisation-associated outcomes in acutely hospitalised older adults.

METHODS

The electronic databases MEDLINE, CINAHL, and Embase were searched for studies including older adults (above age 65) hospitalised in acute internal wards. The search included the following key terms: 'accelerometer', 'step count', 'hospital', 'internal ward', and 'older adults'. Step count measurement linked to short- and/or long-term outcome(s) during and/or after hospitalisation. All types of articles (except reviews) in English from 1990 to May 2020 were considered. The Newcastle-Ottawa Scale was used to assess the quality of the included observational studies. Randomised controlled trials (RCT) were evaluated using the PEDro scale. The review protocol was registered with PROSPERO International Prospective Register of Systematic Reviews. PRISMA guidelines were followed and a PRISMA checklist for reporting systematic reviews completed.

RESULTS

The search yielded 1340 articles, and of those, the inclusion criteria were met by 12 studies: eight prospective, three interventional (one randomised controlled trial), and one case-control. These studies included three major adverse hospitalisation outcomes associated with step count: functional decline, longer length of stay, and higher re-hospitalisation rate; however, the large heterogeneity in the studies' methodology makes meta-analysis impossible.

CONCLUSIONS

Daily step count during hospitalisation of older adults is negatively associated with adverse outcomes, but causation cannot be inferred due to inconsistent outcomes and various methodological limitations. More studies are needed to illuminate causal pathways and mechanisms underlying these relationships, especially to differentiate between the relative contribution of personal versus environmental factors.

Egg protein supplementation improved upper body muscle strength and protein intake in community-dwelling older adult females who attended congregate meal sites or adult learning centers: A pilot randomized controlled trial

Background: Older adults that utilize community-based nutrition services are at higher nutritional risk than the general aging population, yet studies on the efficacy of protein interventions in this population are lacking. Aim: A double-blinded randomized controlled pilot study trial evaluated the impact of egg white protein supplementation on muscle mass, strength, and physical function in predominantly low-income Latina community-dwelling adult females aged 60 or older with reduced muscle strength or function. Methods: Participants (mean age = 73.6  ±  8.3 years) were randomly assigned to receive a daily dried egg white (20 g protein) or isocaloric maltodextrin supplement for 6 months (n = 16 intervention; n = 13 control). The primary outcome measure was appendicular skeletal muscle mass. Secondary outcomes were measures of muscle strength and function and dietary protein intake. Comparisons of baseline demographics were conducted using t-tests and χ² or Fisher's exact tests. Differences between groups were assessed using general linear models, adjusted for baseline values, and differences within groups were assessed using paired t-tests or Kruskal-Wallis. Results: No significant between-group differences were found for all measures, but protein intake, handgrip strength, and the number of arm curls significantly improved in the intervention group. Under-recruitment of study participants and a high dropout rate impacted the ability of this study to detect significant differences between groups. Conclusion: Daily egg white protein supplementation increases protein intake and supports upper body physical function in older adults, but additional studies are needed to investigate its role in the prevention of age-related muscle mass decline in older adults. Trial #NCT03530774 (https://clinicaltrials.gov/ct2/show/NCT03530774).

Modulation of Bone and Joint Biomarkers, Gut Microbiota, and Inflammation Status by Synbiotic Supplementation and Weight-Bearing Exercise: Human Study Protocol for a Randomized Controlled Trial

BACKGROUND

There is strong evidence suggesting that prebiotics and probiotics regulate gut microbiota, reducing inflammation and thereby potentially improving bone health status. Similarly, mechanistic evidence suggests that either low-impact or high-impact weight-bearing exercises improve body composition and consequently increase bone mineral density in individuals with osteoporosis and osteoarthritis.

OBJECTIVE

This study aims to investigate the effects of a synbiotic (probiotic+prebiotic) supplementation, an exercise intervention, or a combination of both on gut microbiota, inflammation, and bone biomarkers in postmenopausal women.

METHODS

A total of 160 postmenopausal women from New Zealand will be recruited and randomized to one of four interventions or treatments for 12 weeks: control, synbiotic supplementation, exercise intervention, or synbiotic supplementation and exercise. The primary outcome measure is the bone and joint biomarkers at baseline and week 12, whereas the gut microbiota profile and inflammatory cytokine measurements will serve as the secondary outcome measures at baseline and week 12. Baseline data and exercise history will be used to assess, allocate, and stratify participants into treatment measures.

RESULTS

Recruitment of participants will begin in September 2021, and the anticipated completion date is June 2022.

CONCLUSIONS

To the best of our knowledge, this will be the first randomized controlled trial to analyze the effects of both a synbiotic supplement and an exercise intervention in postmenopausal women. On the basis of the results obtained, a combination of synbiotic supplements and exercise might serve as a noninvasive approach to manage and/or improve body composition and bone health in postmenopausal women.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12620000998943p; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=380336&isClinicalTrial=False.

Personalized multicomponent exercise programs using smartphone technology among older people: protocol for a randomized controlled trial

BACKGROUND

Optimal application of the recently updated World Health Organization (WHO) guidelines for exercise in advanced age necessitates an accurate adjustment for the age-related increasing variability in biological age and fitness levels, alongside detailed recommendations across a range of motor fitness components, including balance, strength, and flexibility. We previously developed and validated a novel tool, designed to both remotely assess these fitness components, and subsequently deliver a personalized exercise program via smartphone. We describe the design of a prospective randomized control trial, comparing the effectiveness of the remotely delivered personalized multicomponent exercise program to either WHO exercise guidelines or no intervention.

METHODS

Participants (n = 300) are community dwelling, healthy, functionally independent, cognitively intact volunteers aged ≥65 at low risk for serious fall injuries, assigned using permuted block randomization (age/gender) to intervention, active-control, or control group. The intervention is an 8-week program including individually tailored exercises for upper/lower body, flexibility, strength, and balance (dynamic, static, vestibular); active-controls receive exercising counselling according to WHO guidelines; controls receive no guidance. Primary outcome is participant fitness level, operationalized as 42 digital markers generated from 10 motor fitness measures (balance, strength, flexibility); measured at baseline, mid-trial (4-weeks), trial-end (8-weeks), and follow-up (12-weeks). Target sample size is 300 participants to provide 99% power for moderate and high effect sizes (Cohen's f = 0.25, 0.40 respectively).

DISCUSSION

The study will help understand the value of individualized motor fitness assessment used to generate personalized multicomponent exercise programs, delivered remotely among older adults.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04181983.

Insulin resistance and muscle weakness are synergistic risk factors for silent lacunar infarcts: the Bunkyo Health Study

Insulin resistance and muscle weakness are risk factors for silent lacunar infarcts (SLI), but it is unclear whether they are still independent risk factors when adjusted for each other. In addition, the effect of their combination on SLI is completely unknown. We evaluated SLI, insulin sensitivity, and knee extensor muscle strength by magnetic resonance imaging, PREDIM, and dynamometer, respectively, in 1531 elderly people aged 65–84 years living in an urban area of Tokyo. Among the study subjects, 251 (16.4%) had SLI. Impaired insulin sensitivity (High; 1.00 [reference], Medium; 1.53 [95% confidence interval (CI) 0.94–2.48], Low; 1.86 [1.02–3.39], p for trend 0.047) and reduced muscle strength (High; 1.00 [reference], Medium; 1.40 [0.98–2.02], Low; 1.49 [1.04–2.15], p for trend 0.037) were independently associated with increased risk for SLI in the fully adjusted model. In terms of combined, subjects classified as having the lowest insulin sensitivity and lowest strength were 4.33 times (95% CI 1.64–11.45) more likely to have a SLI than those classified as having the highest insulin sensitivity and highest strength. Impaired insulin sensitivity and reduced muscle strength were independently associated with higher risk of SLI in elderly subjects, and their combination synergistically increased this risk.

Positive Self-Perceptions of Aging Play a Significant Role in Predicting Physical Performance among Community-Dwelling Older Adults

Self-perceptions of aging (SPA) is associated with various health-related outcomes, including physical performance. No previous study has investigated the potential predictive influence of SPA on physical performance among Swedish community-dwelling older adults. This was a cross-sectional study using a random sample of 153 Swedish community-dwelling individuals aged 70 and older. Multiple logistic regression analysis was performed, using the subscale “Attitude Towards Own Aging” of the Philadelphia Geriatric Center Morale Scale, as a measure of SPA. The Short Physical Performance Battery (SPPB) was dichotomized and used as the outcome variable. SPA was a significant predictor (OR = 1.546, CI = 1.066–2.243) of physical performance, adjusted for age, cognitive function, and life-space mobility. Further analyses revealed significant sex differences, with SPA not being included in the model for the men whilst it was still a significant predictor (OR = 1.689, CI = 1.031–2.765) of physical performance in the group of women. SPA plays a significant role in predicting physical performance among Swedish community-dwelling older adults. To further clarify this relationship and its consequences, future longitudinal research should focus on the relationship between SPA, physical performance, and fall risk.

Quantity versus quality: Age-related differences in muscle volume, intramuscular fat, and mechanical properties in the triceps surae

With aging comes reductions in the quality and size of skeletal muscle. These changes influence the force-generating capacity of skeletal muscle and contribute to movement deficits that accompany aging. Although declines in strength remain a significant barrier to mobility in older adults, the association between age-related changes in muscle structure and function remain unresolved. In this study, we compared age-related differences in (i) muscle volume and architecture, (ii) the quantity and distribution of intramuscular fat, and (iii) muscle shear modulus (an index of stiffness) in the triceps surae in 21 younger (24.6 ± 4.3 years) and 15 older (70.4 ± 2.4 years) healthy adults. Additionally, we explored the relationship between muscle volume, architecture, intramuscular fat and ankle plantar flexion strength in young and older adults. Magnetic resonance imaging was used to determine muscle volume and intramuscular fat content. B-mode ultrasound was used to quantify muscle architecture, shear-wave elastography was used to measure shear modulus, and ankle strength was measured during maximal isometric plantar flexion contractions. We found that older adults displayed higher levels of intramuscular fat yet similar muscle volumes in the medial (MG) and lateral gastrocnemius (LG) and soleus, compared to younger adults. These age-related higher levels of intramuscular fat were associated with lower muscle shear modulus in the LG and MG. We also found that muscle physiological cross-sectional area (PCSA) that accounted for age-associated differences in intramuscular fat showed a modest increase in its association with ankle strength compared to PCSA that did not account for fat content. This highlights that skeletal muscle fat infiltration plays a role in age-related strength deficits, but does not fully explain the age-related loss in muscle strength, suggesting that other factors play a more significant role.

Preliminary Investigations Into the Effect of Exercise-Induced Muscle Damage on Systemic Extracellular Vesicle Release in Trained Younger and Older Men

Background: Exercise-induced muscle damage (EIMD) results in transient muscle inflammation, strength loss, and muscle soreness and may cause subsequent exercise avoidance. Research has recently proven that skeletal muscle can also release extracellular vesicles (EVs) into the circulation following a bout of exercise. However, EV’s potential role, including as a biomarker, in the response to eccentric resistance exercise stimulus remains unclear.

Methods: Twelve (younger, n=7, 27.0±1.5years and older, n=5, 63.0±1.0years) healthy, physically active males, undertaking moderate, regular physical activity (3–5 times per week) performed a unilateral high intensity eccentric exercise protocol. Venous plasma was collected for assessment of EVs and creatine kinase (CK) prior to EIMD, immediately after EIMD, and 1–72h post-EIMD, and maximal voluntary isometric contraction (MVIC) and delayed onset muscle soreness (DOMS) were assessed at all time points, except 1 and 2h post-EIMD.

Results: A significant effect of both time (p=0.005) and group (p<0.001) was noted for MVIC, with younger participants’ MVIC being higher throughout. Whilst a significant increase was observed in DOMS in the younger group (p=0.014) and in the older group (p=0.034) following EIMD, no significant differences were observed between groups. CK was not different between age groups but was altered following the EIMD (main effect of time p=0.026), with increased CK seen immediately post-, at 1 and 2h post-EIMD. EV count tended to be lower in older participants at rest, relative to younger participants (p=0.056), whilst EV modal size did not differ between younger and older participants pre-EIMD. EIMD did not substantially alter EV modal size or EV count in younger or older participants; however, the alteration in EV concentration (ΔCount) and EV modal size (ΔMode) between post-EIMD and pre-EIMD negatively associated with CK activity. No significant associations were noted between MVIC or DOMS and either ΔCount or ΔMode of EVs at any time point.

Conclusion: These findings suggest that profile of EV release, immediately following exercise, may predict later CK release and play a role in the EIMD response. Exercise-induced EV release profiles may therefore serve as an indicator for subsequent muscle damage.

Nutrients with anabolic/anticatabolic, antioxidant, and anti-inflammatory properties: Targeting the biological mechanisms of aging to support musculoskeletal health

Old age is associated with declines in bone density and muscle mass and function, which predisposes to mobility disability, falls, and fractures. Poor nutritional status, a risk factor for several age-related pathologies, becomes prevalent in old age and contributes to the structural and functional changes of the musculoskeletal system that increases the risk of osteoporosis, sarcopenia, osteosarcopenia, and physical frailty. The biological mechanisms underpinning these pathologies often overlap and include loss of proteostasis, impaired redox functioning, and chronic low-grade inflammation. Thus, provision of nutrients with anabolic/anticatabolic, antioxidant, and anti-inflammatory properties may be an effective strategy to offset these age-related pathologies. We searched PUBMED for pre-clinical and clinical work examining the effects of nutrients with a combined effect on muscle and bone. This review summarizes recent evidence on the mechanisms of action and potential clinical use of nutrients that concomitantly improve muscle and bone health in older persons.

Association between plasma procollagen type III N-terminal peptide (P3NP) levels and physical performance in elderly men: The Korean Frailty and Aging Cohort Study (KFACS)

BACKGROUND

Physical performance decline associated with aging is clinically important in the development of disability in the older population. More recently, procollagen type III N-terminal peptide (P3NP) and synaptosomal-associated protein of 25 kDa (SNAP25) have been suggested as potential biomarkers for physical performance decline.

OBJECTIVE

The objective of this pilot study was to examine plasma P3NP and SNAP25 levels in relation to muscle mass, strength, and performance status, and to investigate the association of plasma P3NP and SNAP25 levels with sarcopenia components.

METHODS

Seventy-nine community-dwelling elderly men (mean age: 78.1 ± 3.5 years) were randomly selected and matched by age from the Korean Frailty and Aging Cohort Study. The sample was classified into the "normal," "low muscle mass only," "sarcopenia," and "low physical performance only" groups according to the criteria of the Asian Working Group for Sarcopenia 2019. Estimates and 95% confidence intervals (CIs) of log P3NP and log SNAP25 levels by muscle mass, strength, and performance status were obtained using a generalized linear model. Pearson correlations and multiple linear regression analyses were used to assess the association of log P3NP and log SNAP25 levels with appendicular skeletal muscle mass (ASM) index, handgrip strength, and physical performance.

RESULTS

Log P3NP levels tended to be associated with low physical performance compared with the normal group (estimate = 0.54; 95% CI = -0.05, 1.14; p = 0.072). Log P3NP levels were inversely associated with physical performance (short physical performance battery and five-times sit-to-stand test) after adjusting for potential confounders (all p < 0.05) and tended to have an inverse association with gait speed (p = 0.078). Log P3NP levels tended to have a positive correlation with the ASM index (r² = 0.042; p = 0.070), but not with handgrip strength (r² = 0.0009; p = 0.795). However, no significant association between plasma SNAP25 levels and physical performance was observed.

CONCLUSION

Plasma P3NP levels might be a potential biomarker for decreased physical performance in elderly men. Further studies with larger sample sizes are needed to confirm our findings.

Matrigel 3D bioprinting of contractile human skeletal muscle models recapitulating exercise and pharmacological responses

A key to enhance the low translatability of preclinical drug discovery are in vitro human three-dimensional (3D) microphysiological systems (MPS). Here, we show a new method for automated engineering of 3D human skeletal muscle models in microplates and functional compound screening to address the lack of muscle wasting disease medication. To this end, we adapted our recently described 24-well plate 3D bioprinting platform with a printhead cooling system to allow microvalve-based drop-on-demand printing of cell-laden Matrigel containing primary human muscle precursor cells. Mini skeletal muscle models develop within a week exhibiting contractile, striated myofibers aligned between two attachment posts. As an in vitro exercise model, repeated high impact stimulation of contractions for 3 h by a custom-made electrical pulse stimulation (EPS) system for 24-well plates induced interleukin-6 myokine expression and Akt hypertrophy pathway activation. Furthermore, the known muscle stimulators caffeine and Tirasemtiv acutely increase EPS-induced contractile force of the models. This validated new human muscle MPS will benefit development of drugs against muscle wasting diseases. Moreover, our Matrigel 3D bioprinting platform will allow engineering of non-self-organizing complex human 3D MPS.

Alave-Furrer et al adapted their recently-developed 3D bioprinting platform to allow microvalve-based drop-on-demand printing of cell-laden Matrigel containing primary human muscle precursor cells. Their bioprinting platform recapitulated aspects of exercise and pharmacological responses and thus could aid the engineering of more complex 3D microphysiological systems.

Exogenous parathyroid hormone attenuates ovariectomy-induced skeletal muscle weakness in vivo

Osteoporosis commonly affects the elderly and is associated with significant morbidity and mortality. Loss of bone mineral density induces muscle atrophy and increases fracture risk. However, muscle lipid content and droplet size are increased by aging and mobility impairments, inversely correlated with muscle function, and a cause of reduced motor function. Teriparatide, the synthetic form of human parathyroid hormone (PTH) 1-34, has been widely used to treat osteoporosis. Although PTH positively affects muscle differentiation in vitro, the precise function and mechanisms of muscle mass and power preservation are still poorly understood, especially in vivo. In this study, we investigated the effect of PTH on skeletal muscle atrophy and dysfunction using an ovariectomized murine model. Eight-week-old female C57BL/6J mice were ovariectomized or sham-operated. Within each surgical group, the mice were divided into PTH injection or control subgroups. Motor function was evaluated based on grip strength, treadmill running, and lactic acid concentration. PTH receptor was expressed in skeletal muscle cells and myoblasts. PTH inhibited ovariectomy-induced bone loss but not uterine atrophy or increased body weight; PTH not only abolished ovariectomy-induced reduction in grip strength and maximum running speed, but also significantly reduced the ovariectomy-induced increase in lactic acid concentration (compared with that observed in the vehicle control). PTH also abrogated the ovariectomy-induced reduction in the oxidative capacity of muscle fibers, their cross-sectional area, and intramyocellular lipid content, and induced cell proliferation, cell migration, and muscle differentiation, while reducing lipid secretion by C2C12 myoblasts via the Wnt/β-catenin pathway. PTH significantly ameliorated muscle weakness and attenuated exercise-induced lactate levels in ovariectomized mice. Our in vitro study demonstrated that PTH/Wnt signaling regulated the proliferation, migration, and differentiation of myoblasts and also reduced lipid secretion in myoblasts. Thus, PTH could regulate several aspects of muscle function and physiology, and may represent a novel therapeutic strategy for patients with osteoporosis.

Quantification of the Link between Timed Up-and-Go Test Subtasks and Contractile Muscle Properties

Frailty and falls are a major public health problem in older adults. Muscle weakness of the lower and upper extremities are risk factors for any, as well as recurrent falls including injuries and fractures. While the Timed Up-and-Go (TUG) test is often used to identify frail members and fallers, tensiomyography (TMG) can be used as a non-invasive tool to assess the function of skeletal muscles. In a clinical study, we evaluated the correlation between the TMG parameters of the skeletal muscle contraction of 23 elderly participants (22 f, age 86.74 ± 7.88) and distance-based TUG test subtask times. TUG tests were recorded with an ultrasonic-based device. The sit-up and walking phases were significantly correlated to the contraction and delay time of the muscle vastus medialis (ρ = 0.55-0.80, p < 0.01). In addition, the delay time of the muscles vastus medialis (ρ = 0.45, p = 0.03) and gastrocnemius medialis (ρ = -0.44, p = 0.04) correlated to the sit-down phase. The maximal radial displacements of the biceps femoris showed significant correlations with the walk-forward times (ρ = -0.47, p = 0.021) and back (ρ = -0.43, p = 0.04). The association of TUG subtasks to muscle contractile parameters, therefore, could be utilized as a measure to improve the monitoring of elderly people's physical ability in general and during rehabilitation after a fall in particular. TUG test subtask measurements may be used as a proxy to monitor muscle properties in rehabilitation after long hospital stays and injuries or for fall prevention.

Administration of tauroursodeoxycholic acid attenuates dexamethasone-induced skeletal muscle atrophy

Glucocorticoids are known to induce skeletal muscle atrophy by suppressing protein synthesis and promoting protein degradation. Tauroursodeoxycholic acid (TUDCA) has beneficial effects in several diseases, such as hepatobiliary disorders, hindlimb ischemia and glucocorticoid-induced osteoporosis. However, the effects of TUDCA on glucocorticoid -induced skeletal muscle atrophy remains unknown. Therefore, in the present research, we explored the effects of TUDCA on dexamethasone (DEX)-induced loss and the potential mechanisms involved. We found TUDCA alleviated DEX-induced muscle wasting in C2C12 myotubes, identified by improved myotube differentiation index and expression of myogenin and MHC. And it showed that TUDCA activated the Akt/mTOR/S6K signaling pathway and inhibited FoxO3a transcriptional activity to decreased expression of MuRF1 and Atrogin-1, while blocking Akt by MK2206 blocked these effects of TUDCA on myotubes. Besides, TUDCA also attenuated DEX-induced apoptosis of myotubes. Furthermore, TUDCA was administrated to the mouse model of DEX-induced skeletal muscle atrophy. The results showed that TUDCA improved DEX-induced skeletal muscle atrophy and weakness (identified by increased grip strength and prolonged running exhaustive time) in mice by suppression of apoptosis, reduction of protein degradation and promotion of protein synthesis. Taken together, our research proved for the first time that TUDCA protected against DEX-induced skeletal muscle atrophy not only by improving myogenic differentiation and protein synthesis, but also through decreasing protein degradation and apoptosis of skeletal muscle.

Lactobacillus plantarum HY7715 Ameliorates Sarcopenia by Improving Skeletal Muscle Mass and Function in Aged Balb/c Mice

Sarcopenia is a loss of muscle mass and function in elderly people and can lead to physical frailty and fall-related injuries. Sarcopenia is an inevitable event of the aging process that substantially impacts a person's quality of life. Recent studies to improve muscle function through the intake of various functional food materials are attracting attention. However, it is not yet known whether probiotics can improve muscle mass and muscle strength and affect physical performance. Lactobacillus plantarum HY7715 (HY7715) is a lactic acid bacteria isolated from kimchi. The present research shows that L. plantarum HY7715 increases physical performance and skeletal muscle mass in 80-week-old aged Balb/c male mice. HY7715 not only induces myoblast differentiation and mitochondrial biogenesis but also inhibits the sarcopenic process in skeletal muscle. In addition, HY7715 recovers the microbiome composition and beta-diversity shift. Therefore, HY7715 has promise as a functional probiotic supplement to improve the degeneration of muscle function that is associated with aging.

Effects of gravitational and iso-inertial resistance trainings using rating of perceived exertion on lower limbs muscle force and power abilities and metabolic cost of walking in healthy older adults

BACKGROUND

The purpose was to compare the effects of 8-weeks resistance training programs (Flywheel Iso-inertial, FW vs Traditional Gravity-Dependent Resistance Training, GD) performed twice a week at the same rate of perceived exertion (RPE), on muscle force and power capacities and physical performance in healthy older participants.

METHODS

Twenty-four participants were randomly assigned to either FW (male/female: 7/5, age: 67.1±3.8 yr) or GD (male/female: 6/6, age 68.3±3.0 yr) group. Knee extension maximal isometric voluntary contractions (MVC), lower limb maximal explosive power (MEP), six-minute walking distance (6MWT), timed "Up & Go" scores (TUG), metabolic cost of walking (CW) and agonist-antagonist co-contraction time (CCT) during walking were evaluated before and after training.

RESULTS

absolute MEP and MEP normalized for body mass increased only in FW than GD group (+10.8% vs +0.31%, p: 0.056, respectively; +14.8% vs +13.9%, p<0.001, respectively). Both training modalities improved MVC to a similar extent (+11.1% in FW vs +13.4% in GD, p<0.001). Analogously, 6MWT distance increased in FW and GD (+5.2 and +5.5%, p<0.041, respectively). No effects of time and training modality were observed on the other parameters.

CONCLUSIONS

The study suggests that when FW and GD are administered at the same RPE with FW performed at higher movement speed in the concentric phase, both the trainings generate similar improvements in muscle strength but only the former can promote greater muscle power enhancements than GD in healthy older adults.

Sarcopenia: Etiology, Nutritional Approaches, and miRNAs

Sarcopenia, an age-related decline in skeletal muscle mass and function, dramatically affects the quality of life. Although there is a consensus that sarcopenia is a multifactorial syndrome, the etiology and underlying mechanisms are not yet delineated. Moreover, research about nutritional interventions to prevent the development of sarcopenia is mainly focused on the amount and quality of protein intake. The impact of several nutrition strategies that consider timing of food intake, anti-inflammatory nutrients, metabolic control, and the role of mitochondrial function on the progression of sarcopenia is not fully understood. This narrative review summarizes the metabolic background of this phenomenon and proposes an integral nutritional approach (including dietary supplements such as creatine monohydrate) to target potential molecular pathways that may affect reduce or ameliorate the adverse effects of sarcopenia. Lastly, miRNAs, in particular those produced by skeletal muscle (MyomiR), might represent a valid tool to evaluate sarcopenia progression as a potential rapid and early biomarker for diagnosis and characterization.

Association between serum lactate dehydrogenase and frailty among individuals with metabolic syndrome

While metabolic syndrome (MetS) is associated with frailty, the correlation of serum lactate dehydrogenase (sLDH) and frailty with MetS remain uncertain. To investigate the relationship between sLDH and frail components in the US with MetS. A total of 4,066 participants aged 40-90 years were assessed from the database of the third National Health and Nutrition Examination Survey, 1988-1994. The participants were classified into MetS and non-MetS groups. Multivariate logistic regression analysis with four models were performed to assess the odds ratio (OR) of the divided tertiles of sLDH levels with frailty, and frail components including slow walking (SW), weakness, exhaustion, low physical activity (LPA), and low body weight (LBW). Higher sLDH levels were positively associated with frailty in the MetS group (p = 0.024) but not in non-MetS group (p = 0.102). After covariate adjustments, the OR of frailty in the upper two tertiles compared to the lowest tertile and revealed statistical significance (p < 0.05). Frail components of SW, weakness, exhaustion, and LPA were associated with higher sLDH (p < 0.05) except for LBW in MetS and non-MetS groups. The results demonstrated the strong association of higher sLDH levels and frailty among US individuals with MetS.

Effects of Neuromuscular Electrical Stimulation on Quadriceps Muscle Strength and Mass in Healthy Young and Older Adults: A Scoping Review

OBJECTIVE

Although neuromuscular electrical stimulation (NMES) has been used as a safe and relevant complement to voluntary resistance training, its effectiveness in increasing quadriceps femoris muscle strength and mass in healthy young and older adults has not been determined. The aim of this scoping review was to assess the effects of NMES on quadriceps muscle strength and mass in healthy young and older adults.

METHODS

CENTRAL, Pedro, MEDLINE, and PubMed were searched from inception to September 2019. Randomized controlled trials (RCTs) that compared NMES with control group or voluntary resistance training for healthy young and older adults were included. Study characteristics, primary and secondary outcome parameters, and details of the NMES intervention were extracted by 2 reviewers. Only studies for which full text was available in English were included.

RESULTS

Thirty-two RCTs including 796 healthy participants were identified as being eligible for young adults, and 5 RCTs including 123 healthy participants were identified as being eligible for older adults. The available evidence strongly suggests that NMES improves quadriceps muscle strength compared with a control group in young adults, but its efficacy seems lower than that of voluntary resistance training. The available limited evidence regarding the effects of NMES on quadriceps muscle mass compared with control in young adults is inconclusive, with 3 RCTs showing positive effects and 3 RCTs not showing positive effects. The very limited available evidence from 5 RCTs in older adults suggests that NMES might be beneficial for increasing quadriceps muscle strength and mass.

CONCLUSION

Overall, the evidence indicates that NMES is an efficacious method for increasing quadriceps muscle strength in young adults, whereas its impact on muscle mass requires further investigations. In addition, the effectiveness of NMES needs to be confirmed in older adults on the basis of more high-quality RCTs with larger sample sizes.

IMPACT

This scoping review of 37 RCTs including 919 people is the first study, to the authors' knowledge, to show that the use of NMES increases quadriceps muscle strength in young adults and might improve quadriceps muscle strength compared with control interventions in older adults. In both young and older adults, the effects of NMES on quadriceps muscle mass are still unclear.

Mobility performance impacts mortality risk in community-dwelling healthy older adults in Japan: a prospective observational study

BACKGROUND

The timed up and go (TUG) test assesses balance and mobility performance.

AIM

This study aims to investigate the association between TUG time and mortality in Japanese older persons and to clarify possible moderation effects on mortality and TUG time.

METHODS

In all, 874 participants who were ≥ 65 years of age completed the TUG test and had their anthropometric parameters and physical functions measured. We investigated the association between all-cause mortality and TUG using a Cox regression model that included confounders, and explored the time associated with mortality using a restricted cubic spline. We also performed subgroup analyses to explore whether age, sex, and body mass index (BMI) affected the relationship between TUG time and mortality.

RESULTS

The median age and mean follow-up period were 74 and 8.5 years, respectively. Median TUG time was 7.4 s and the prevalence of mortality was 25.7%. TUG time in one second was positively associated with an increased risk of total mortality [hazard ratio (HR): 1.054 (1.016-1.093); P = 0.005] in the Cox regression model. The positive association of mortality and TUG time was present when the TUG was over 10.5 s in the restricted cubic spline curve. Older age (75 years or older) moderated the relationship between TUG time and mortality [P_interaction = 0.096].

CONCLUSION

This study demonstrates that TUG time is associated with all-cause mortality in Japanese older adults.

A Diet Including Red Bell Pepper Juice and Soy Protein Suppress Physiological Markers of Muscle Atrophy in Mice

Although muscle atrophy can be caused by disuse and lifestyle-related syndromes, it may be possible to prevent this condition through dietary intervention. We hypothesized that a diet including red bell pepper juice (RBPJ) and soy protein isolate (SPI) would prevent muscle atrophy. Accordingly, an experimental diet containing RBPJ and/or SPI was administered for 18 d to normal C57BL/6J mice. The control group was administered a casein diet. Four days before the end of the test period, denervation-induced muscle atrophy and/or sham operation were performed. Anterior tibialis muscle samples were then obtained to assess muscle degradation and perform metabolome analysis. Under the denervation condition, the 20% SPI diet did not alter the mRNA expression levels of muscle atrophy marker genes compared with the 20% casein group. Although the diet comprising RBPJ and 20% casein did not prevent muscle atrophy compared with the control group, the diet containing RBPJ and 20% SPI did. Metabolome analysis revealed that a diet including RBPJ and SPI induced a greater than 1.5-fold change in the levels of 20 muscle atrophy-related metabolites. In particular, the level of S-adenosylmethionine, which concerned with energy metabolism and lifespan, showed a strong positive correlation with the muscle atrophy marker. These findings suggest that a diet including RBPJ and soy protein suppress gene expressions related with muscle atrophy. Further research in humans is needed to confirm whether a combination of RBPJ and SPI can indeed prevent muscle atrophy.

Role of the Myokine Irisin on Bone Homeostasis: Review of the Current Evidence

Bone is a highly dynamic tissue that is constantly adapting to micro-changes to facilitate movement. When the balance between bone building and resorption shifts more towards bone resorption, the result is reduced bone density and mineralization, as seen in osteoporosis or osteopenia. Current treatment strategies aimed to improve bone homeostasis and turnover are lacking in efficacy, resulting in the search for new preventative and nutraceutical treatment options. The myokine irisin, since its discovery in 2012, has been shown to play an important role in many tissues including muscle, adipose, and bone. Evidence indicate that irisin is associated with increased bone formation and decreased bone resorption, leading to reduced risk of osteoporosis in post-menopausal women. In addition, low serum irisin levels have been found in individuals with osteoporosis and osteopenia. Irisin targets key signaling proteins, promoting osteoblastogenesis and reducing osteoclastogenesis. The present review summarizes the existing evidence regarding the effects of irisin on bone homeostasis.

Personalized Exercise Programs Based upon Remote Assessment of Motor Fitness: A Pilot Study among Healthy People Aged 65 Years and Older

BACKGROUND

The World Health Organization has recently updated exercise guidelines for people aged >65 years, emphasizing the inclusion of multiple fitness components. However, without adequate recognition of individual differences, these guidelines may be applied using an approach that "one-size-fits-all." Within the shifting paradigm toward an increasingly personalized approach to medicine and health, it is apparent that fitness components display a significant age-related increase in variability. Therefore, it is both logical and necessary to perform an accurate individualized assessment of multiple fitness components prior to optimal prescription for a personalized exercise program.

OBJECTIVE

The aim of the study was to test the feasibility and effectiveness of a novel tool able to remotely assess balance, flexibility, and strength using smartphone sensors (accelerometer/gyroscope), and subsequently deliver personalized exercise programs via the smartphone.

METHODS

We enrolled 52 healthy volunteers (34 females) aged 65+ years, with normal cognition and low fall risk. Baseline data from remote smartphone fitness assessment were analyzed to generate 42 fitness digital markers (DMs), used to guide personalized exercise programs (×5/week for 6 weeks) delivered via smartphone. Programs included graded exercises for upper/lower body, flexibility, strength, and balance (dynamic, static, and vestibular). Participants were retested after 6 weeks.

RESULTS

Average age was 74.7 ± 6.4 years; adherence was 3.6 ± 1.7 exercise sessions/week. Significant improvement for pre-/posttesting was observed for 10/12 DMs of strength/flexibility for upper/lower body (sit-to-stand repetitions/duration; arm-lift duration; torso rotation; and arm extension/flexion). Balance improved significantly for 6/10 measures of tandem stance, with consistent (nonsignificant) trends observed across 20 balance DMs of tandem walk and 1 leg stance. Balance tended to improve among the 37 participants exercising ≥3/week.

DISCUSSION

These preliminary results provide a proof of concept, with high adherence and improved fitness confirming the benefits of remote fitness assessment for guiding home personalized exercise programs among healthy adults aged >65 years. Further examination of the application within a randomized control study is necessary, comparing the personalized exercise program to general guidelines among healthy older adults, as well as specific populations, such as those with frailty, deconditioning, cognitive, or functional impairment. The study tool offers the opportunity to collect big data, including additional variables, with subsequent utilization of artificial intelligence to optimize the personalized exercise program.

Skeletal muscle atrophy: From mechanisms to treatments

Skeletal muscle is a crucial tissue for movement, gestural assistance, metabolic homeostasis, and thermogenesis. It makes up approximately 40% of the total body weight and 50% of total protein. However, several pathological abnormalities (e.g., chronic diseases, cancer, long-term infection, aging) can induce an imbalance in skeletal muscle protein synthesis and degradation, which triggers muscle wasting and even leads to atrophy. Skeletal muscle atrophy is characterized by weakening, shrinking, and decreasing muscle mass and fiber cross-sectional area at the histological level. It manifests as a reduction in force production, easy fatigue and decreased exercise capability, along with a lower quality of life. Mechanistically, there are several pathophysiological processes involved in skeletal muscle atrophy, including oxidative stress and inflammation, which then activate signal transduction, such as the ubiquitin proteasome system, autophagy lysosome system, and mTOR. Considering the great economic and social burden that muscle atrophy can inflict, effective prevention and treatment strategies are essential but still limited. Exercise is widely acknowledged as the most effective therapy for skeletal muscle atrophy; unfortunately, it is not applicable for all patients. Several active substances for skeletal muscle atrophy have been discovered and evaluated in clinical trials, however, they have not been marketed to date. Knowledge is being gained on the underlying mechanisms, highlighting more promising treatment strategies in the future. In this paper, the mechanisms and treatment strategies for skeletal muscle atrophy are briefly reviewed.

Muscle synergy differences between voluntary and reactive backward stepping

Reactive stepping responses are essential to prevent falls after a loss of balance. It has previously been well described that both voluntary and reactive step training could improve the efficacy of reactive stepping in different populations. However, the effect of aging on neuromuscular control during voluntary and reactive stepping remains unclear. Electromyography (EMG) signals during both backward voluntary stepping in response to an auditory cue and backward reactive stepping elicited by a forward slip-like treadmill perturbation during stance were recorded in ten healthy young adults and ten healthy older adults. Using muscle synergy analysis, we extracted the muscle synergies for both voluntary and reactive stepping. Our results showed that fewer muscle synergies were used during reactive stepping than during voluntary stepping in both young and older adults. Minor differences in the synergy structure were observed for both voluntary and reactive stepping between age groups. Our results indicate that there is a low similarity of muscle synergies between voluntary stepping and reactive stepping and that aging had a limited effect on the structure of muscle synergies. This study enhances our understanding of the neuromuscular basis of both voluntary and reactive stepping as well as the potential effect of aging on neuromuscular control during balance tasks.

Psychometrics of the Balance Beam Functional Test in C57BL/6 Mice

Aging is associated with a progressive decline in physical function characterized by decreased mobility, which is an important risk factor for loss of independence and reduced quality of life. Functional testing conducted in animals has advanced our understanding of age-related changes in physical ability and contributed to the development of physiologic measurements that can be used to assess functional changes during aging. The balance beam test is one assessment tool used to measure age-related changes in balance and coordination. The goal of this study is to provide analytical examples and psychometric support of a protocol that has been analyzed to show how the number of successive test runs, foot slips, pauses, and hesitations affect the reliability of the primary outcome measure, which is the time to cross the beam. Our results suggest that conducting more than 1 training session, consisting of greater than or equal to 3 successful training runs, followed by at least one test session with no less than 2 successful runs (that is, runs without pauses or hesitations) provides a psychometrically sound outcome. The data presented here indicate that a psychometric approach can improve protocol design and reliability of balance beam measures in mice.

Determinants of dynamic inspiratory muscle strength in healthy trained elderly

BACKGROUND

The S-Index assessed by means of electronic devices is a measure of Inspiratory Muscle Strength (IMS) that highly correlates with the maximal inspiratory pressure (MIP). The variables involved when using regression models for the prediction of IMS/MIP depend on both the sample characteristics and the device or protocol used. In light of the scarce information on the influence of physical activity (PA) on IMS in healthy older adults (OA), together with the incorporation of new assessment devices, the objectives of this research are: 1) to determine which factors influence the IMS in a group of trained OA, using a portable electronic device; and 2) to propose a regression model to improve its assessment and training.

METHODS

One hundred and fifty-nine individuals were assessed for body composition, lung capacity, IMS, and PA. A total of 92 individuals (72.73 ± 4.99 years) were considered for the final sample.

RESULTS

Using age, sex, and weight as control variables, forced expiratory volume in the first second (FEV₁) is the variable which is most likely to be included in the model (80%), without physical fitness appearing to be decisive. In the absence of spirometric variables, cardiorespiratory fitness (6MWT) takes on this role in a predictive model (16%).

CONCLUSIONS

This is the first study proposing IMS predictive formulas considering spirometry and/or physical fitness results for a Spanish, healthy, and trained OAs population. A predictive formula including also the spirometric variables (mainly the FEV₁) might better predict the inspiratory muscle strength. In addition, physical and respiratory functions confirm to be different, so it is necessary for the inspiratory muscles to be trained in a specific way.

Anthropometry as a readily accessible health assessment of older adults

Anthropometry (derived from the Greek Anthropos: human, and metron: measure) refers to the systematic collection, and measurement of the physical characteristics of the human body, primarily body weight, body size, and shape. Anthropometric values are closely related to genetic factors, environmental characteristics, social, and cultural conditions, lifestyle, functional status, and health. Anthropometric measurements can be used to assess risk of malnutrition, obesity, muscle wasting, increased fat mass, and maldistribution of adipose tissue. Potential modifiable factors include circumferences, skinfolds, and body weight. While are height, and the bone diameters are non-modifiable. Kinanthropometry is the study of size, shape, proportionality, composition, biological maturation, and body function, in order to understand the process of growth, exercise, sports performance, and nutrition. Aging of the population, which is associated with increased risk of chronic disease, and disability, is one of the most important demographic changes facing many countries. Anthropometric indicators are simple, portable, non-invasive, inexpensive, and easily applied measurements that can be readily applied in geriatric populations to guide preventative measures, and medical interventions in older adults.

Relationship between phase angle and physical performance measures in community-dwelling older adults

INTRODUCTION

The phase angle (PhA) is a measure of great clinical relevance provided through the Bioelectric Impedance Analysis (BIA). PhA is related to health status. Physical performance measures are also similarly associated to the health status of older individuals, however, studies which asses the relationship between these two measures are scarce.

OBJECTIVE

To identify the relationship between PhA and physical performance measures in community-dwelling older adults in a Brazilian sample.

METHODOLOGY

This was a cross-sectional study in which 200 community-dwelling older adults up to 65 years of age of both genders were recruited. Physical performance was evaluated by walking speed and handgrip strength, and the PhA was derived from BIA. Linear regression models were used to estimate the associations between PhA and physical performance measures. Two models were built: the first model was adjusted by handgrip and walking speed; and the second model additionally included the number of chronic diseases, gender, age and body mass index (BMI).

RESULTS

A total of 200 subjects were evaluated through BIA. Men showed a mean age of 72.13 ± 3.42 years and women 71.94 ± 3.35 years. Mean PhA among men was 5.99 ± 0.67, while the mean obtained for women was 5.43 ± 0.70. Linear regression showed that handgrip strength (β: 0.036; p-value < 0.001; β: 0.024; p-value: 0.005) and walking speed (β: 0.495; p-value: 0.044; β: 0.619, p-value: 0.009) were correlated with the PhA in both models.

CONCLUSION

The results of our study revealed that PhA is a good marker of physical performance for the Brazilian community-dwelling older adults studied.

Sarcopenia: What Is the Origin of This Aging-Induced Disorder?

We here review the loss of muscle function and mass (sarcopenia) in the framework of human healthspan and lifespan, and mechanisms involved in aging. The rapidly changing composition of the human population will impact the incidence and the prevalence of aging-induced disorders such as sarcopenia and, henceforth, efforts to narrow the gap between healthspan and lifespan should have top priority. There are substantial knowledge gaps in our understanding of aging. Heritability is estimated to account for only 25% of lifespan length. However, as we push the expected lifespan at birth toward those that we consider long-lived, the genetics of aging may become increasingly important. Linkage studies of genetic polymorphisms to both the susceptibility and aggressiveness of sarcopenia are still missing. Such information is needed to shed light on the large variability in clinical outcomes between individuals and why some respond to interventions while others do not. We here make a case for the concept that sarcopenia has a neurogenic origin and that in manifest sarcopenia, nerve and myofibers enter into a vicious cycle that will escalate the disease progression. We point to gaps in knowledge, for example the crosstalk between the motor axon, terminal Schwann cell, and myofiber in the denervation processes that leads to a loss of motor units and muscle weakness. Further, we argue that the operational definition of sarcopenia should be complemented with dynamic metrics that, along with validated biomarkers, may facilitate early preclinical diagnosis of individuals vulnerable to develop advanced sarcopenia. We argue that preventive measures are likely to be more effective to counter act aging-induced disorders than efforts to treat manifest clinical conditions. To achieve compliance with a prescription of preventive measures that may be life-long, we need to identify reliable predictors to design rational and convincing interventions.

Chronic intermittent hypoxia aggravates skeletal muscle aging by down-regulating Klc1/grx1 expression via Wnt/β-catenin pathway

OBJECTIVE

Sleep breathing disorder may affect skeletal muscle decline in the elderly, but the mechanism is not clear. Therefore, this study explores the mechanism of skeletal muscle aging in chronic intermittent hypoxia (CIH) rats.

METHODS

In vitro and in vivo CIH models were constructed in L6 cells and SD rats by treating chronic intermittent hypoxia. Pathological changes of skeletal muscle in vivo were measured by hematoxylin-eosin (HE) staining. Cell proliferation and apoptosis were detected by CCK-8 and Flow cytometer, respectively. The expression of KLC1/GRX1 and the proteins related to the Wnt/β-catenin pathway were measured by qRT-PCR and western blot.

RESULTS

CIH model was successfully established induced by chronic intermittent hypoxia with lower skeletal muscle index (SMI), increased inward migration of muscle fiber cell nucleus, and muscle cells' distance. The results showed that Wnt/β-catenin signalling was activatedin both L6 cells and CIH rats' model. KLC1 and GRX1 were significantly downregulated in the CIH model. Loss of function showed that downregulation of KLC1 promoted L6 cell and skeletal muscle aging in vitro and in vivo, respectively.

CONCLUSION

Our results demonstrated that CIH aggravated skeletal muscle aging by down-regulating KLC1/GRX1 expression via the Wnt/β-catenin pathway.

The Effects of Lifestyle and Diet on Gut Microbiota Composition, Inflammation and Muscle Performance in Our Aging Society

Living longer is associated with an increased risk of chronic diseases, including impairments of the musculoskeletal and immune system as well as metabolic disorders and certain cancers, each of which can negatively affect the relationship between host and microbiota up to the occurrence of dysbiosis. On the other hand, lifestyle factors, including regular physical exercise and a healthy diet, can affect skeletal muscle and immune aging positively at all ages. Accordingly, health benefits could partly depend on the effect of such interventions that influence the biodiversity and functionality of intestinal microbiota. In the present review, we first discuss the physiological effects of aging on the gut microbiota, immune system, and skeletal muscle. Secondly, we describe human epidemiological evidence about the associations between physical activity and fitness and the gut microbiota composition in older adults. The third part highlights the relevance and restorative mechanisms of immune protection through physical activity and specific exercise interventions during aging. Fourth, we present important research findings on the effects of exercise and protein as well as other nutrients on skeletal muscle performance in older adults. Finally, we provide nutritional recommendations to prevent malnutrition and support healthy active aging with a focus on gut microbiota. Key nutrition-related concerns include the need for adequate energy and protein intake for preventing low muscle mass and a higher demand for specific nutrients (e.g., dietary fiber, polyphenols and polyunsaturated fatty acids) that can modify the composition, diversity, and metabolic capacity of the gut microbiota, and may thus provide a practical means of enhancing gut and systemic immune function.

Age does not affect the relationship between muscle activation and joint work during incline and decline walking

Older compared with younger adults walk with different configurations of mechanical joint work and greater muscle activation but it is unclear if age, walking speed, and slope would each affect the relationship between muscle activation and net joint work. We hypothesized that a unit increase in positive but not negative net joint work requires greater muscle activation in older compared with younger adults. Healthy younger (age: 22.1 yrs, n = 19) and older adults (age: 69.8 yrs, n = 16) ascended and descended a 7° ramp at slow (~1.20 m/s) and moderate (~1.50 m/s) walking speeds while lower-extremity marker positions, electromyography, and ground reaction force data were collected. Compared to younger adults, older adults took 11% (incline) and 8% (decline) shorter strides, and performed 21% less positive ankle plantarflexor work (incline) and 19% less negative knee extensor work (decline) (all p < .05). However, age did not affect (all p > .05) the regression coefficients between the muscle activation integral and positive hip extensor or ankle plantarflexor work during ascent, nor between that and negative knee extensor or ankle dorsiflexor work during descent. With increased walking speed, muscle activation tended to increase in younger but changed little in older adults across ascent (10 ± 12% vs. -1.0 ± 10%) and descent (3.6 ± 10.2% vs. -2.6 ± 7.7%) (p = .006, r = 0.47). Age does not affect the relationship between muscle activation and net joint work during incline and decline walking at freely-chosen step lengths. The electromechanical cost of joint work production does not underlie the age-related reconfiguration of joint work during walking.

Personal Determinants for Physical Activity Behavior of Urban-Dwelling Older Adults in Sri Lanka

Physical inactivity is a vital risk factor for the development and maintenance of chronic ill-health conditions among older adults. This study examined personal factors associated with physical activity (PA) behavior of urban-dwelling older adults in Sri Lanka, a middle-income country in South Asia. A total of 880 older adults (aged ≥60 years) participated in this cross-sectional study. They responded to anthropometrical, health, and socio-demographic data pertaining to their current physical and behavioral status. The mean age of the participants was 70.1 years (SD ±6.0), and the majority (75%) were women. Increasing age, male gender, middle income, having cardiovascular diseases or arthritis, deficiencies in muscle strength and balance, pain, and lower self-rated health were associated with insufficient PA behavior among the participants. Old-age physical activity promotion programs should target older adults in advanced ages and men in particularly, as they are highly vulnerable to sedentary lifestyles. Muscle strength and balance, a neglected area in PA promotion in older adults, seem to play an important role in older adults' participation in physical activities. Incorporation of pain management, and muscle strength and balance techniques into older adults' PA promotion programs would probably increase adherence rates of the participants in such programs.

Unilateral Vocal Cord Paresis During Sleep Endoscopy

Abnormalities of vocal cord motion in children with obstructive sleep apnea (OSA) who undergo drug-induced sleep endoscopy (DISE) are not frequently described. A 17-year-old female with a history of asthma, reflux, and bipolar disorder had a history of poor sleep. Polysomnography (PSG) showed apnea-hypopnea index (AHI) of 13.9/hr, obstructive AHI 10.3/hr, and oxygen saturation nadir 87%. Physical exam showed BMI 34 and 3+ tonsils. She underwent DISE with propofol infusion, which showed partial obstruction at the palatine and lingual tonsil levels, a posteriorly displaced epiglottis along with immobility of the left vocal cord. Tonsillectomy was performed as planned. At her post-op visit, laryngoscopy showed normal vocal cord motion bilaterally. Post-operative PSG was improved.

Effects and Moderators of Exercise on Sarcopenic Components in Sarcopenic Elderly: A Systematic Review and Meta-Analysis

Background: Sarcopenia is a muscle disease in loss of muscle strength, mass, and function associated with aging. Although protective effects of exercise on muscle mass and function are generally recognized, research findings in sarcopenic adults are inconsistent. It is necessary to conduct a systematic review to determine the effects of exercise on muscle strength, body composition, and physical performance in older adults with sarcopenia, and to examine the potential moderators including sociodemographic characteristics and exercise-related factors.

Methods: Six electronical academic databases (Medline, Embase, CINAHL, Scopus, Cochrane Library, and SPORTDiscus) were used to retrieve the eligible studies from inception to May 2020. Two reviewers independently selected and extracted the data from each included study, and effect sizes were calculated by employing random-effect models with 95% confidential interval (CI). The Physiotherapy Evidence Database (PEDro) scale was used to assess study quality.

Results: Seventeen studies (985 participants with sarcopenia, aged 67.6–86 years) were included in this review study. The meta-analytic results showed significant improvements in muscle strength [grip strength, SMD = 0.30, 95% CI (0.15, 0.45), I² = 6%, p < 0.01; knee extension, SMD = 0.32, 95% CI (0.15, 0.50), I² = 0%, p < 0.01; and chair and stand, SMD = 0.56, 95% CI (0.30, 0.81), I² = 36%, p < 0.01], in physical performance [timed up and go, SMD = 0.74, 95% CI (0.48, 1.00), I² = 0%, p < 0.01; and gait speed, SMD = 0.59, 95% CI (0.35, 0.82), I² = 62%, p < 0.01], and in body composition [skeletal muscle mass index, SMD = 0.37, 95% CI (0.15, 0.58), I² = 16%, p < 0.01; and appendicular skeletal muscle, SMD = 0.31, 95% CI (0.13, 0.49), I² = 20%, p < 0.01]. However, there were no significant differences in other body composition (SMD = 0.20–0.36). Additionally, meta-regression revealed that the higher percent of female participants was significantly associated with improved gait speed (β = 0.0096, p = 0.03) and decreased skeletal muscle mass index (β = −0.0092, p = 0.01).

Conclusions: The current meta-analysis suggests that exercise is a beneficial therapy, which has protective effects for older adults with sarcopenia. Some beneficial effects may be moderated by gender and exercise intensity.

Association Between Interleukin-12 and Sarcopenia

Background

Emerging studies have proposed that cytokines secreted following macrophage polarization may contribute to skeletal muscle aging. The current study primarily aimed to determine whether these cytokines have an impact on the progression of sarcopenia in an elderly population.

Methods

In total, 120 elderly adults aged 65 years and older who underwent health examinations from 2015 to 2019 were included in this retrospective study. Sarcopenia was based on the criteria proposed by the European Working Group on Sarcopenia in Older People in 2019. Macrophages and cytokines datasets were obtained from Gene Expression Omnibus (GEO) database. Comprehensive assessments were performed for muscle strength, muscle mass, gait speed, tumor growth factor-β (TGF-β), and interleukin-12 (IL-12). Thereafter, the association between sarcopenia and cytokines was analyzed using regression models.

Results

Low muscle strength and low-speed gait were negatively associated with IL-12 [β: −8.96 (95% CI: −14.12, −3.79) and −7.16 (95% CI: −12.54, −1.78), respectively]. Participants with more sarcopenia components and more severe sarcopenia had lower IL-12 (P for trend < 0.001). Conversely, more amount of sarcopenia components were associated with increased TGF-β (P for trend < 0.05). A definite diagnosis of sarcopenia was associated with decreased IL-12 and increased TGF-β with β of −8.96 (95% CI: −14.12, −3.79) and 147.75 (95% CI: 36.27, 259.23). Furthermore, increased IL-12 levels were significantly associated with reduced occurrence of sarcopenia with and odd ratio (OR) of 0.36 (95% CI: 0.15–0.834).

Conclusion

Our findings on the relationship between cytokines and age-related muscle loss showed that IL-12 may be an early diagnosis indicator for sarcopenia in the elderly population.

Singapore multidisciplinary consensus recommendations on muscle health in older adults: assessment and multimodal targeted intervention across the continuum of care

BACKGROUND

The rapidly aging societies worldwide and in Singapore present a unique challenge, requiring an integrated multidisciplinary approach to address high-value targets such as muscle health. We propose pragmatic evidence-based multidisciplinary consensus recommendations for the assessment and multi-modal management of muscle health in older adults (≥65 years) across the continuum of care.

METHODS

The recommendations are derived from an in-depth review of published literature by a multidisciplinary working group with clinical experience in the care of the older population in both acute and community settings.

RESULTS

The panel recommends screening for muscle impairment using the SARC-F questionnaire, followed by assessment for low muscle strength (handgrip strength or 5-times chair stand test ≥10 s as a surrogate for lower limb strength) to diagnose possible/probable sarcopenia. For uncomplicated cases, lifestyle modifications in exercise and diet can be initiated in the community setting without further assessment. Where indicated, individuals diagnosed with possible/probable sarcopenia should undergo further assessment. Diagnosis of sarcopenia should be based on low muscle strength and low muscle mass (bioimpedance analysis, dual-energy X-ray absorptiometry or calf circumference as a surrogate). The severity of sarcopenia should be determined by assessment of physical performance (gait speed or 5-times chair stand test ≥12 s as a surrogate for gait speed). To treat sarcopenia, we recommend a combination of progressive resistance-based exercise training and optimization of nutritional intake (energy, protein and functional ingredients). High quality protein in sufficient quantity, to overcome anabolic resistance in older adults, and distributed throughout the day to enable maximum muscle protein synthesis, is essential. The addition of resistance-based exercise training is synergistic in improving the sensitivity of muscle protein synthesis response to the provision of amino acids and reducing anabolic resistance. An expected dose-response relationship between the intensity of resistance-based training, lean mass and muscle strength is described.

CONCLUSIONS

Reviewed and endorsed by the Society of Rehabilitation Medicine Singapore and the Singapore Nutrition and Dietetics Association, these multidisciplinary consensus recommendations can provide guidance in the formulation of comprehensive and pragmatic management plans to improve muscle health in older adults in Singapore and Asia.

The Associations of Handgrip Strength and Leg Extension Power Asymmetry on Incident Recurrent Falls and Fractures in Older Men

BACKGROUND

Evaluating asymmetries in muscle function could provide important insights for fall risk assessments. We sought to determine the associations of 1) handgrip strength (HGS) asymmetry, and 2) leg extension power (LEP) asymmetry on risk of incident recurrent falls and fractures in older men.

METHODS

There were 5,730 men with HGS asymmetry data and 5,347 men with LEP asymmetry data from the Osteoporotic Fractures in Men (MrOS) study. A handgrip dynamometer measured HGS and a Nottingham Power Rig ascertained LEP. Percent difference in maximal HGS between hands was calculated, and asymmetric HGS was defined as men in the highest quartile of dissimilarity for HGS between hands. The same approach was used to determine asymmetric LEP. Participants self-reported falls every four-months after the baseline exam, and persons with ≥2 falls in the first year were considered recurrent fallers. Fractures and their dates of occurrence were self-reported and confirmed with radiographic reports.

RESULTS

Older men in the highest HGS asymmetry quartile had a 1.20 (95% confidence interval (CI): 1.01-1.43) relative risk for incident recurrent falls. Likewise, men in the highest HGS asymmetry quartile had a higher risk for incident fractures: 1.41 (CI: 1.02-1.96) for hip, 1.28 (CI: 1.04-1.58) for major osteoporotic, and 1.24 (CI: 1.06-1.45) for non-spine. There were no significant associations between LEP asymmetry and recurrent falls or fractures.

CONCLUSIONS

Asymmetric HGS could be a novel risk factor for falls and fractures that is more feasible to measure than LEP. Fall risk assessments should consider evaluating muscle function, including HGS asymmetry.

Age-Dependent Remodeling in Infrapatellar Fat Pad Adipocytes and Extracellular Matrix: A Comparative Study

The infrapatellar fat pad (IFP) is actively involved in knee osteoarthritis (OA). However, a proper description of which developmental modifications occur in the IFP along with age and in absence of joint pathological conditions, is required to adequately describe its actual contribution in OA pathophysiology. Here, two IFP sources were compared: (a) IFP from healthy young patients undergoing anterior-cruciate ligament (ACL) reconstruction for ACL rupture (n = 24); (b) IFP from elderly cadaver donors (n = 23). After histopathological score assignment to confirm the absence of inflammatory features (i.e., inflammatory infiltrate and increased vascularity), the adipocytes morphology was determined; moreover, extracellular matrix proteins were studied through histology and Second Harmonic Generation approach, to determine collagens content and orientation by Fast Fourier Transform and OrientationJ. The two groups were matched for body mass index. No inflammatory signs were observed, while higher area, perimeter, and equivalent diameter and volume were detected for the adipocytes in the elderly group. Collagen III displayed higher values in the young group and a lower total collagen deposition with aging was identified. However, collagen I/III ratio and the global architecture of the samples were not affected. A higher content in elastic fibers was observed around the adipocytes for the ACL-IFPs and in the septa cadaver donor-IFPs, respectively. Age affects the characteristics of the IFP tissue also in absence of a pathological condition. Variable mechanical stimulation, depending on age-related different mobility, could be speculated to exert a role in tissue remodeling.