Health Care Costs Associated With Muscle Weakness: A UK Population-Based Estimate

Muscle Traits, Sarcopenia, and Sarcopenic Obesity: A Vitamin D Mendelian Randomization Study

(1) Background: Observational studies associate vitamin D deficiency with muscle disorders, while some clinical trial data support a minor association between the vitamin and skeletal muscle performance in healthy subjects. Vitamin D receptor knockout mice studies confirm the relationship between vitamin D and skeletal muscle; however, causal inference in humans is challenging due to the ethical implications of including vitamin D-deficient participants in randomized trials. This study uses genetic methods to safely explore causal underpinnings for the relationship between 25(OH)D concentrations and skeletal muscle-related traits, including grip strength and combined arm skeletal muscle mass, and extends this analysis to suspected pathophysiology in the form of probable sarcopenia and sarcopenic obesity. (2) Methods: We conducted Mendelian randomization (MR) analyses in up to 307,281 participants from the UK Biobank of whom 25,414 had probable sarcopenia and 16,520 had sarcopenic obesity. In total, 35 variants were used to instrument 25(OH)D and MR analyses conducted using multiple approaches. (3) Results: Genetic analyses provided support for a relationship between genetically predicted higher 25(OH)D and skeletal muscle traits, with linear MR analyses for grip strength showing 0.11 kg (95% CI 0.04, 0.19) greater contractile force per 10 unit higher 25(OH)D, while there was a modest association with skeletal muscle mass (0.01 kg (95% CI 0.003, 0.02) greater muscle mass). For probable sarcopenia risk, there was suggestive evidence for lower odds by higher 25(OH)D (OR 0.96 (95% CI 0.92, 1.00)); however, this did not reflect an association with sarcopenic obesity (OR 0.97 (95% CI 0.93, 1.02)), but was seen in probable sarcopenia cases who were not obese (OR 0.92 (95% CI 0.86, 0.98)). Results were similar across multiple MR approaches. (4) Conclusions: Our study supports a causal relationship between 25(OH)D and skeletal muscle health. While evidence for benefit did not extend to lower risk of sarcopenic obesity, effective vitamin D-deficiency prevention strategies may help reduce age-related muscle weakness.

A Comprehensive Review of Pathological Mechanisms and Natural Dietary Ingredients for the Management and Prevention of Sarcopenia

Sarcopenia is characterized by an age-related loss of skeletal muscle mass and function and has been recognized as a clinical disease by the World Health Organization since 2016. Substantial evidence has suggested that dietary modification can be a feasible tool to combat sarcopenia. Among various natural dietary ingredients, the present study focused on botanical and marine extracts, phytochemicals, and probiotics. Aims of this review were (1) to provide basic concepts including the definition, diagnosis, prevalence, and adverse effects of sarcopenia, (2) to describe possible pathological mechanisms including protein homeostasis imbalance, inflammation, mitochondrial dysfunction, and satellite cells dysfunction, and (3) to analyze recent experimental studies reporting potential biological functions against sarcopenia. A recent literature review for dietary ingredients demonstrated that protein homeostasis is maintained via an increase in the PI3K/Akt pathway and/or a decrease in the ubiquitin-proteasome system. Regulation of inflammation has primarily targeted inhibition of NF-κB signaling. Elevated Pgc-1α or Pax7 expression reverses mitochondrial or satellite cell dysfunction. This review provides the current knowledge on dietary components with the potential to assist sarcopenia prevention and/or treatment. Further in-depth studies are required to elucidate the role of and develop various dietary materials for healthier aging, particularly concerning muscle health.

Urinary antibiotic exposure and low grip strength risk in community-dwelling elderly Chinese by gender and age

Emerging studies have shown that environmental contaminants were related to decreased handgrip strength. Nevertheless, no prior research has investigated the relationship of exposure to environmental antibiotics with grip strength. Thus, we explored the relationship between urinary antibiotic burden and grip strength among the elderly in China. This study consisted of 451 men and 539 women from the baseline survey of a cohort study. Commonly used antibiotics for humans and animals were detected in 990 urine samples through a biomonitoring method. Grip strength was measured by an electronic dynamometer. We examined the associations of antibiotic exposure with low grip strength (LGS), grip strength, and grip strength index, respectively. Results suggested that 34.9% of participants developed LGS, and 93.0% of individuals were exposed to 1-10 antibiotics. Among women, oxytetracycline (Quartile 2: odds ratio: 2.97, 95% confidence interval: 1.36-6.50), florfenicol (Quartile 3: 2.60 [1.28-5.27]), fluoroquinolones (Quartile 4: 1.88 [1.07-3.30]), and chloramphenicols (Quartile 3: 2.73 [1.35-5.51]) could enhance LGS risk. Among men, ofloxacin (Quartile 2: 3.32 [1.45-7.59]) increased LGS risk, whereas tetracycline (Quartile 2: 0.31 [0.11-0.88]) was implicated in reduced LGS risk. In participants < 70 years, ofloxacin (Quartile 2: 3.00 [1.40-6.42]) could increase LGS risk. For participants who were 70 years of age or older, veterinary antibiotics (Quartile 3: 1.73 [1.02-2.94]) were linked to a 73% increased risk of LGS. Our findings suggested that antibiotics mainly pertained to LGS, and there were gender and age disparities in associations between antibiotic exposure and muscle strength indicators in the elderly Chinese population.

Cost-effectiveness analysis of sarcopenia management interventions in Iran

OBJECTIVES

Identification the optimal management intervention of sarcopenia is a concern of health systems. We aimed to analyze the cost-effectiveness of sarcopenia management strategies in Iran.

METHODS

We constructed a lifetime Markov model based on natural history. The strategies comparedincluded exercise training, nutritional supplements, whole body vibration (WBV), and various exercise interventions and nutritional supplement combinations. A total of 7 strategies was evaluated in addition to the non-intervention strategy. Parameter values were extracted from primary data and the literature, and the costs and Quality-adjusted life years (QALYs) were calculated for each strategy. Deterministic and probabilistic sensitivity analysis, including the expected value of perfect information (EVPI), was also performed to determine the robustness of the model. Analyses were performed using the 2020 version of TreeAge Pro software.

RESULTS

All seven strategies increased lifetime effectiveness (QALYs). The protein and Vitamin D₃ (P + D) strategy had the highest effectiveness values among all strategies. After removing the dominated strategies, the estimated ICER for the P + D compared to Vitamin D₃ alone (D) strategy was calculated as $131,229. Considering the cost-effectiveness threshold ($25,249), base-case results indicated that the D strategy was the most cost-effective strategy in this evaluation. Sensitivity analysis of model parameters also demonstrated the robustness of results. Also, EVPI was estimated at $273.

CONCLUSIONS

Study results, as the first economic evaluation of sarcopenia management interventions, showed that despite the higher effectiveness of D + P, the D strategy was the most cost-effective. Completing clinical evidence of various intervention options can lead to more accurate results in the future.

Repurposing Approved Drugs for Sarcopenia Based on Transcriptomics Data in Humans

Sarcopenia, characterized by age-related loss of muscle mass, strength, and decreased physical performance, is a growing public health challenge amid the rapidly ageing population. As there are no approved drugs that target sarcopenia, it has become increasingly urgent to identify promising pharmacological interventions. In this study, we conducted an integrative drug repurposing analysis utilizing three distinct approaches. Firstly, we analyzed skeletal muscle transcriptomic sequencing data in humans and mice using gene differential expression analysis, weighted gene co-expression analysis, and gene set enrichment analysis. Subsequently, we employed gene expression profile similarity assessment, hub gene expression reversal, and disease-related pathway enrichment to identify and repurpose candidate drugs, followed by the integration of findings with rank aggregation algorithms. Vorinostat, the top-ranking drug, was also validated in an in vitro study, which demonstrated its efficacy in promoting muscle fiber formation. Although still requiring further validation in animal models and human clinical trials, these results suggest a promising drug repurposing prospect in the treatment and prevention of sarcopenia.

Oligonucleotide Therapeutics for Age-Related Musculoskeletal Disorders: Successes and Challenges

Age-related disorders of the musculoskeletal system including sarcopenia, osteoporosis and arthritis represent some of the most common chronic conditions worldwide, for which there remains a great clinical need to develop safer and more efficacious pharmacological treatments. Collectively, these conditions involve multiple tissues, including skeletal muscle, bone, articular cartilage and the synovium within the joint lining. In this review, we discuss the potential for oligonucleotide therapies to combat the unmet clinical need in musculoskeletal disorders by evaluating the successes of oligonucleotides to modify candidate pathological gene targets and cellular processes in relevant tissues and cells of the musculoskeletal system. Further, we discuss the challenges that remain for the clinical development of oligonucleotides therapies for musculoskeletal disorders and evaluate some of the current approaches to overcome these.

Acute resistance exercise training does not augment mitochondrial remodelling in master athletes or untrained older adults

Background: Ageing is associated with alterations to skeletal muscle oxidative metabolism that may be influenced by physical activity status, although the mechanisms underlying these changes have not been unraveled. Similarly, the effect of resistance exercise training (RET) on skeletal muscle mitochondrial regulation is unclear. Methods: Seven endurance-trained masters athletes ([MA], 74 ± 3 years) and seven untrained older adults ([OC]. 69 ± 6 years) completed a single session of knee extension RET (6 x 12 repetitions, 75% 1-RM, 120-s intra-set recovery). Vastus lateralis muscle biopsies were collected pre-RET, 1 h post-RET, and 48h post-RET. Skeletal muscle biopsies were analyzed for citrate synthase (CS) enzyme activity, mitochondrial content, and markers of mitochondrial quality control via immunoblotting. Results: Pre-RET CS activity and protein content were ∼45% (p < .001) and ∼74% greater in MA compared with OC (p = .006). There was a significant reduction (∼18%) in CS activity 48 h post-RET (p < .05) in OC, but not MA. Pre-RET abundance of individual and combined mitochondrial electron transport chain (ETC) complexes I-V were significantly greater in MA compared with OC, as were markers of mitochondrial fission and fusion dynamics (p-DRP-1Ser616, p-MFFSer146, OPA-1 & FIS-1, p < .05 for all). Moreover, MA displayed greater expression of p-AMPKThr172, PGC1α, TFAM, and SIRT-3 (p < .05 for all). Notably, RET did not alter the expression of any marker of mitochondrial content, biogenesis, or quality control in both OC and MA. Conclusion: The present data suggest that long-term aerobic exercise training supports superior skeletal muscle mitochondrial density and protein content into later life, which may be regulated by greater mitochondrial quality control mechanisms and supported via superior fission-fusion dynamics. However, a single session of RET is unable to induce mitochondrial remodelling in the acute (1h post-RET) and delayed (48 h post-RET) recovery period in OC and MA.

The Relationship between Skeletal Muscle Mass and Bone Mass at Different Sites in Older Adults

INTRODUCTION

It has been well recognized that sarcopenia is closely related with osteoporosis, while the relationship between bone mass at different sites and muscle mass remains largely unexplored. This study aims to explore the relationship between bone mass at different sites and skeletal muscle mass in older adults.

METHODS

A total of 228 patients over 65 years old were enrolled in this study, and then 180 valid participants with accessible dual-energy X-ray absorptiometry (DXA) scanning data and absence of malignant tumors, mobility disorders, serious liver and kidney disease, and cardiac insufficiency were selected (138 male and 42 female). These individuals were further divided into control group and low skeletal muscle mass index (SMI) group. DXA scanning was used to access skeletal muscle mass and bone mass. SMI or body mass index was defined as appendicular muscle mass or weight divided by squared height, respectively. Low SMI <7.0 kg/m2 in male or <5.4 kg/m2 in female was defined as low SMI; while the bone density score at or below 2.5 standard deviations (T-score) below normal peak bone values, was regarded as osteoporosis.

RESULTS

The average age of enrolled patients was 82.72 years; the ratios of osteoporosis, low SMI, and low SMI with osteoporosis were 48.8%, 23.3%, and 15.0%, respectively. Compared with the control group, the prevalence of osteoporosis was higher, and the total bone mass and bone mass at various sites including limbs, spine, and pelvis, were all lower in low SMI group. Correlation analysis showed that SMI was positively related with total bone mass and bone mass at various sites. Covariance analysis showed that only total bone mass and appendicular bone mass decreased with decreasing SMI. After multiple adjustment, osteoporosis was positively related with the prevalence of low SMI, as evidenced by logistic regression analysis (odds ratio = 1.33, 95% confidential interval: 1.04-3.24, p = 0.045). Furthermore, compared with the highest quartile of appendicular bone mass, the lowest quartile was related with the increasing prevalence of low SMI (odds ratio = 7.29, 95% confidential interval: 1.21-67.45, p = 0.042).

CONCLUSION

Compared with the other sites, the bone mass reduction at limbs of older adults was positively associated with skeletal muscle loss. It may be more beneficial to increase bone mass at the limbs for improved sarcopenia prevention and therapy. Further investigations are needed to explore the effects of other confounders (e.g., energy, calcium and vitamin D intake, and physical activity) on the osteoporosis and sarcopenia in older adults.

A comparison of physical activity, muscle strength, and sleep between people with type 2 diabetes in Kuwait and the UK: A cross-sectional study

Background

The aim of the current study was to determine the prevalence of low muscle strength and to evaluate physical activity and sleep characteristics in people with type 2 diabetes in Kuwait. Additionally, equivalent data from the UK Biobank cohort were compared.

Methods

People with type 2 diabetes from the UK Biobank (n = 23,570) and Kuwaiti cohorts (n = 3,135) were included in this cross-sectional study. Self-reported sleep, physical activity, and muscle strength were compared between the cohorts, using linear and logistic regression, with adjustments for age, sex, and duration of diabetes.

Results

Physical activity levels (-937 (-1,097, -851) Met-min/week: standardized B-coefficient -0.42 (-0.47, -0.37)) and grip strength (3.2 (-3.58, -2.82) kg: standardized B-coefficient (-0.29 (-0.32, -0.26)) were lower in the Kuwaiti cohort, and the odds of having short sleep (OR 1.32 (1.19,1.46), being classed as inactive (OR 8.70 (7.59, 9.98), and having muscle weakness (OR 1.88 (1.69, 2.09) were higher. These analyses were adjusted for age, sex, and duration of diabetes.

Conclusions

The aim of the current study was to determine the prevalence of low muscle strength and to evaluate physical activity and sleep characteristics in people with type 2 diabetes in Kuwait. Additionally, equivalent data from the UK Biobank cohort were compared.

The effectiveness of the Healthworks Staying Steady community-based falls prevention exercise programme to improve physical function in older adults: a 6-year service evaluation

Background

Falls prevention exercise programmes are evidence-based and recommended for improving physical function in older adults. However, few service evaluations exist to assess the effectiveness of community-delivered interventions in practice.

Methods

We conducted a six-year, retrospective evaluation of the community-delivered Staying Steady programme (Healthworks, United Kingdom). Staying Steady is a 27-week, tailored strength and balance programme delivered in a group setting (1-h, once/week) and at home (30–40 min, 2–3 times/week). Participants were referred by healthcare professionals, or self-referred, due to a history or risk of falling. Routinely collected outcome measures (30-s chair stand, Timed Up and Go, four-stage balance test, and patient reported outcomes; including ‘fear of falling’ and ‘ability to manage health’) were analysed. Factors associated with programme completion were reported. The intervention effect on physical function was analysed in subgroups: participants used arms to chair-stand or a walking-aid at both (‘aided’), neither (‘unaided’), or one assessment timepoint (‘aided at baseline only’ or ‘aided at follow-up only’).

Results

There were 1,426 referrals; 835 (67.3%) participants enrolled on to the Staying Steady programme, 406 (32.7%) declined, 185 (13.0%) were inappropriately referred and excluded from analysis. After enrolling, 451 (54.0%) participants completed, and 384 (46.0%) dropped out. Chair stand performance improved in participants who were unaided (n = 264; median 2.0 [1.0, 4.0] repetitions; P < 0.001), or aided at baseline, follow-up or both (n = 170, P < 0.05). Timed Up and Go performance improved in the unaided (n = 387; median ˗3.1 [˗5.4, ˗1.4] s, P < 0.001), and aided at baseline only (n = 32; median ˗4.9 [˗10.8, ˗3.4] s, P < 0.001) groups. Four-stage balance performance improved (n = 295; median 1.0 [0.0, 1.0] points, P < 0.001). After programme completion, participants self-reported an improved ability to manage their health and daily activities, improved confidence, and a reduced fear of falling. Presence of chronic obstructive pulmonary disease, fear of falling, prescribed nutritional support, disability and social deprivation influenced non-completion of Staying Steady.

Conclusions

Completing Staying Steady improved physical function in older adults. Methods to encourage retention of participants from groups associated with low uptake and adherence should be investigated.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-13832-3.

Acute Sarcopenia after Elective and Emergency Surgery

Sarcopenia is an increasingly recognised condition of loss of muscle mass and function. The European Working Group on Sarcopenia in Older People 2 (EWSOP2) updated their definition in 2018, emphasising the importance of low muscle strength in diagnosis. Acute sarcopenia has been arbitrarily defined as sarcopenia lasting less than 6 months. This review highlights the pathophysiology involved in muscle wasting following surgery, focussing on hormonal factors, inflammation, microRNAs, and oxidative stress. Biomarkers such as GDF-15, IGF-1 and various microRNAs may predict post-surgical muscle loss. The impact of existing sarcopenia on various types of surgery and incident muscle wasting following surgery is also described. The gaps in research found include the need for longitudinal studies looking in changes in muscle strength and quantity following surgery. Further work is needed to examine if biomarkers are replicated in other surgery to consolidate existing theories on the pathophysiology of muscle wasting.

Association between oral health markers and decline in muscle strength and physical performance in later life: longitudinal analyses of two prospective cohorts from the UK and the USA

BACKGROUND

Poor oral health could be associated with changes in musculoskeletal health over time. This aim of this study was to investigate the longitudinal relationship between oral health and decline in physical function in later life.

METHODS

We did a prospective analysis of two cohorts of older adults (aged 70 years or older) including men from the British Regional Heart Study (BRHS; n=612), and men and women from the Health, Aging and Body Composition (Health ABC) Study (n=1572), followed up for about 8 years. Data were available for clinical or self-reported oral health measures, muscle (grip) strength, and physical performance (chair stand and gait speed). ANCOVA models were used to assess the association between oral health and follow-up physical function scores. Multivariate logistic regression models were used to examine the associations between oral health and decline in physical function over the follow-up period. In the BRHS, changes in oral health and physical function were also assessed. All models were adjusted for relevant sociodemographic, behavioural, and health-related factors.

FINDINGS

In the BRHS, complete tooth loss and difficulty eating were associated with weaker grip strength at follow-up, and periodontal status was associated with decline in gait speed. In the Health ABC Study, complete tooth loss, poor self-rated oral health, and the presence of one oral health problem were associated with slower gait speed at follow-up. In both studies, dry mouth was associated with declines in physical function. In the BRHS, deterioration of dentition (tooth loss) over the follow-up period was associated with decline in chair stand speed (adjusted odds ratio 2·34 [95% CI 1·20-4·46]), as was deterioration in difficulty eating (2·41 [1·04-5·60]).

INTERPRETATION

Oral health problems are associated with poorer physical function and greater decline in physical function in older adults, and could be an indicator of individuals at risk of reduced physical capacity and subsequent frailty and disability in later life.

FUNDING

The Dunhill Medical Trust and the US National Institutes of Health-National Institute of Dental and Craniofacial Research.

Protective Effects of the Chalcone-Based Derivative AN07 on Inflammation-Associated Myotube Atrophy Induced by Lipopolysaccharide

Inflammation is a major cause of skeletal muscle atrophy in various diseases. 2-Hydroxy-4′-methoxychalcone (AN07) is a chalcone-based peroxisome-proliferator-activated receptor gamma (PPARγ) agonist with various effects, such as antiatherosclerosis, anti-inflammation, antioxidative stress, and neuroprotection. In this study, we examined the effects of AN07 on protein homeostasis pathway and mitochondrial function in inflammation-associated myotube atrophy induced by lipopolysaccharides (LPS). We found that AN07 significantly attenuated NF-κB activation, inflammatory factors (TNF-α, IL-1β, COX-2, and PGE2), Nox4 expression, and reactive oxygen species levels in LPS-treated C2C12 myotubes. Moreover, AN07 increased SOD2 expression and improved mitochondrial function, including mitochondrial membrane potential and mitochondrial oxygen consumption rate. We also demonstrated that AN07 attenuated LPS-induced reduction of myotube diameter, MyHC expression, and IGF-1/IGF-1R/p-Akt-mediated protein synthesis signaling. Additionally, AN07 downregulated LPS-induced autophagy–lysosomal protein degradation molecules (LC3-II/LC3-I and degraded p62) and ubiquitin–proteasome protein degradation molecules (n-FoxO1a/MuRF1/atrogin-1). However, the regulatory effects of AN07 on protein synthesis and degradation signaling were inhibited by the IGF-1R inhibitor AG1024 and the PI3K inhibitor wortmannin. In addition, the PPARγ antagonist GW9662 attenuated the effects of AN07 against LPS-induced inflammation, oxidation, and protein catabolism. In conclusion, our findings suggest that AN07 possesses protective effects on inflammation-induced myotube atrophy and mitochondrial dysfunction.

International depiction of the cost of functional independence limitations among older adults living in the community: a systematic review and cost-of-impairment study

BACKGROUND

Functional independence limitations restrict older adult self-sufficiency and can reduce quality of life. This systematic review and cost of impairment study examined the costs of functional independence limitations among community dwelling older adults to society, the health care system, and the person.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines this systematic review included community dwelling older adults aged 60 years and older with functional independence limitations. Databases (Cochrane Database of Systematic Reviews, EconLit, NHS EED, Embase, CINAHL, AgeLine, and MEDLINE) were searched between 1990 and June 2020. Two reviewers extracted information on study characteristics and cost outcomes including mean annual costs of functional independence limitations per person for each cost perspective (2020 US prices). Quality was assessed using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist.

RESULTS

85 studies were included. The mean annual total costs per person (2020 US prices) were: $27,380.74 (95% CI: [$4075.53, $50,685.96]) for societal, $24,195.52 (95% CI: [$9679.77, $38,711.27]) for health care system, and $7455.49 (95% CI: [$2271.45, $12,639.53]) for personal. Individuals with cognitive markers of functional independence limitations accounts for the largest mean costs per person across all perspectives. Variations across studies included: cost perspective, measures quantifying functional independence limitations, cost items reported, and time horizon.

CONCLUSIONS

This study sheds light on the importance of targeting cognitive markers of functional independence limitations as they accounted for the greatest costs across all economic perspectives.

Associations between muscle mass/strength and healthcare costs/use for patients with cancer: A systematic literature review

PURPOSE

To review published scientific evidence evaluating the potential associations between muscle mass/strength and healthcare use/costs for patients with cancer.

METHODS

In accordance with the predefined protocol for a systematic literature review, studies assessing potential associations between muscle mass/strength and healthcare costs/use in cancer patients were searched on MEDLINE (via Ovid) and on the NHS Economic Evaluation Database in September 2021. Study selection, data extraction and quality assessment were performed by two independent reviewers.

RESULTS

Of 613 studies identified, five met our inclusion criteria. Various outcomes were investigated: for length of hospital stay, one out of three studies reported an association between lower muscle mass and longer hospital stay; for hospital admission, the two identified studies did not highlight muscle weakness as a predictor of hospital admission; for hospital readmission, one out of two studies reported that patients with lower muscle mass had higher rates of hospital readmission; for costs and cost-effectiveness, results of two randomized controlled trials were mixed, with total costs of the intervention higher in one study and lower in the other, leading to opposite cost-effectiveness results.

CONCLUSION

Only five studies evaluating potential associations between mass/strength and healthcare use/costs have been highlighted within this systematic review. The amount of evidence is limited but the studies are also very heterogeneous in regards of study designs, sample size, and type of population included. This important heterogeneity prevents drawing strong conclusions. Because of limited data available, more high quality longitudinal studies are needed to further investigate the relationship between muscle mass/strength and healthcare costs/use.

Effects of supervised high-intensity hardstyle kettlebell training on grip strength and health-related physical fitness in insufficiently active older adults: the BELL pragmatic controlled trial

The Ballistic Exercise of the Lower Limb (BELL) trial examined the efficacy and safety of a pragmatic hardstyle kettlebell training program in older adults. Insufficiently active men and women aged 59–79 years, were recruited to a 6-month repeated measures study, involving 3-months usual activity and 3-months progressive hardstyle kettlebell training. Health-related physical fitness outcomes included: grip strength [GS], 6-min walk distance [6MWD], resting heart rate [HR], stair-climb [SC], leg extensor strength [LES], hip extensor strength [HES], Sit-To-Stand [STS], vertical jump [CMVJ], five-times floor transfer [5xFT], 1RM deadlift, body composition (DXA), attendance, and adverse events. Sixteen males (68.8 ± 4.6 yrs, 176.2 ± 7.8 cm, 90.7 ± 11.0 kg, 29.2 ± 2.6 kg/m²) and sixteen females (68.6 ± 4.7 yrs, 163.9 ± 5.4 cm, 70.4 ± 12.7 kg, 26.3 ± 4.9 kg/m²) were recruited. Compliance with the supervised exercise program was very high (91.5%). Kettlebell training increased GS (R: MD = 7.1 kg 95% CI [4.9, 9.3], L: MD = 6.3 kg 95% CI [4.1, 8.4]), 6MWD (41.7 m, 95% CI [17.9, 65.5]), 1RM (16.2 kg, 95% CI [2.4, 30.0]), 30 s STS (3.3 reps, 95% CI [0.9, 5.7]), LES (R: MD = 61.6 N, 95% CI [4.4, 118.8]), HES (L: MD = 21.0 N,95% CI [4.2,37.8]), appendicular skeletal lean mass (MD = 0.65 kg, 95% CI [0.08, 1.22]), self-reported health change (17.1%, 95% CI [4.4, 29.8]) and decreased SC time (2.7 s, 95% CI [0.2, 5.2]), 5xFT time (6.0 s, 95% CI [2.2, 9.8]) and resting HR (7.4 bpm, 95% CI [0.7, 14.1]). There were four non-serious adverse events. Mean individual training load for group training sessions during the trial was 100,977 ± 9,050 kg. High-intensity hardstyle kettlebell training was well tolerated and improved grip strength and measures of health-related physical fitness in insufficiently active older adults.

Trial registration: Prospectively registered: 20/08/2019, Australian New Zealand Clinical Trials Registry (ACTRN12619001177145).

Heterogeneity in resistance training-induced muscle strength responses is associated with training frequency and insulin resistance in postmenopausal women

BACKGROUND

In older adults, muscle strength (MS), a key component of sarcopenia, is essential to maintaining independence and physical capacity. The rate of muscle strength decline typically accelerates during the menopausal transition. Although MS has been shown to increase with resistance training (RT), the response to training is quite heterogeneous. Thus, if contributing factors to RT non-responsiveness to MS gains are identified, it may be possible to develop more effective and personalized ways to improve MS or identify individuals who may benefit from RT interventions. This study assessed potential factors that may contribute to MS response heterogeneity in postmenopausal women: training frequency, serum FSH and estrogen levels, adiposity, inflammation marker, and insulin resistance.

METHODS

One hundred and thirteen individuals participated in a 16-week program of supervised RT (3 sets, 8-12 repetitions, and 2-3 times/week). A control group (CTL, n = 63 - no performed the RT) was used as the comparator arm. Body composition (skinfold) and blood samples (metabolic and inflammatory indicators and hormones) were measured at baseline. Knee extensor strength (1RM) was measured at baseline, 8 weeks, and 16 weeks.

RESULTS

Only the RT group increased 1RM after 8 weeks (RT = 14 ± 12% vs. CTL = 6 ± 15%). Both groups increased 1RM after 16 weeks, with the RT group showing a greater increase than the CTL group (RT = 31 ± 23% vs CTL = 13 ± 25%). After 8 weeks of RT, 41 (36% of total) individuals were considered non-responders (based on control group responses) and 27 (24% of total) individuals after 16 weeks. At week 8, lower RT frequency (2 times/week vs. 3 times/week) was associated with higher odds of being non-responder (3 times, P = 0.048). At week 16, lower RT frequency (13 times, P = 0.009) and higher HOMA-IR (for every unit increase, odds increase by 40%, P = 0.022) were associated with higher odds of being non-responder. Higher QUICKI was associated with lower odds of being non-responder (for every unit increase, odds decrease by 16%, P = 0.039). Moreover, higher RT frequency (17 times, P = 0.028) and higher QUICKI (for every unit increase, odds increase by 41%, P = 0.017) were associated with higher odds of becoming a responder at week 16, being a non-responder at week 8.

CONCLUSION

Heterogeneity in RT-induced MS responses is associated with training frequency and insulin resistance in postmenopausal women.

Interleukin-6 potentiates endurance training adaptation and improves functional capacity in old mice

BACKGROUND

Interventions to preserve functional capacities at advanced age are becoming increasingly important. So far, exercise provides the only means to counteract age-related decrements in physical performance and muscle function. Unfortunately, the effectiveness of exercise interventions in elderly populations is hampered by reduced acceptance and compliance as well as disuse complications. We therefore studied whether application of interleukin-6 (IL-6), a pleiotropic myokine that is induced by skeletal muscle activity and exerts broad systemic effects in response to exercise, affects physical performance and muscle function alone or in combination with training in aged mice.

METHODS

Sedentary old male mice (Sed+Saline, n = 15) were compared with animals that received recombinant IL-6 (rIL-6) in an exercise-mimicking pulsatile manner (Sed+IL-6, n = 16), were trained with a moderate-intensity, low-volume endurance exercise regimen (Ex+Saline, n = 13), or were exposed to a combination of these two interventions (Ex+IL-6, n = 16) for 12 weeks. Before and at the end of the intervention, mice underwent a battery of tests to quantify endurance performance, muscle contractility in situ, motor coordination, and gait and metabolic parameters.

RESULTS

Mice exposed to enhanced levels of IL-6 during endurance exercise bouts showed superior improvements in endurance performance (33% more work and 12% greater peak power compared with baseline), fatigue resistance in situ (P = 0.0014 vs. Sed+Saline; P = 0.0199 vs. Sed+IL-6; and P = 0.0342 vs. Ex+Saline), motor coordination (rotarod performance, P = 0.0428), and gait (gait speed, P = 0.0053) following training. Pulsatile rIL-6 treatment in sedentary mice had only marginal effects on glucose tolerance and some gait parameters. No increase in adverse events or mortality related to rIL-6 treatment was observed.

CONCLUSIONS

Administration of rIL-6 paired with treadmill running bouts potentiates the adaptive response to a moderate-intensity low-volume endurance exercise regimen in old mice, while being safe and well tolerated.

Effect of perindopril or leucine on physical performance in older people with sarcopenia: the LACE randomized controlled trial

BACKGROUND

This trial aimed to determine the efficacy of leucine and/or perindopril in improving physical function in older people with sarcopenia.

METHODS

Placebo-controlled, parallel group, double-blind, randomized two-by-two factorial trial. We recruited adults aged ≥ 70 years with sarcopenia, defined as low gait speed (<0.8 m/s on 4 m walk) and/or low handgrip strength (women < 20 kg, men < 30 kg) plus low muscle mass (using sex and body mass index category-specific thresholds derived from normative UK BioBank data) from 14 UK centres. Eligible participants were randomized to perindopril 4 mg or placebo, and to oral leucine powder 2.5 g or placebo thrice daily. The primary outcome was the between-group difference in the short physical performance battery (SPPB) score over 12-month follow-up by repeated-measures mixed models. Results were combined with existing systematic reviews using random-effects meta-analysis to derive summary estimates of treatment efficacy.

RESULTS

We screened 320 people and randomized 145 participants compared with an original target of 440 participants. For perindopril [n = 73, mean age 79 (SD 6), female sex 39 (53%), mean SPPB 7.1 (SD 2.3)] versus no perindopril [n = 72, mean age 79 (SD 6), female sex 39 (54%), mean SPPB 6.9 (SD 2.4)], median adherence to perindopril was lower (76% vs. 96%; P < 0.001). Perindopril did not improve the primary outcome [adjusted treatment effect -0.1 points (95%CI -1.2 to 1.0), P = 0.89]. No significant treatment benefit was seen for any secondary outcome including muscle mass [adjusted treatment effect -0.4 kg (95%CI -1.1 to 0.3), P = 0.27]. More adverse events occurred in the perindopril group (218 vs. 165), but falls rates were similar. For leucine [n = 72, mean age 78 (SD 6), female sex 38 (53%), mean SPPB 7.0 (SD 2.1)] versus no leucine [n = 72, mean age 79 (SD 6), female sex 40 (55%), mean SPPB 7.0 (SD 2.5)], median adherence was the same in both groups (76% vs. 76%; P = 0.99). Leucine did not improve the primary outcome [adjusted treatment effect 0.1 point (95%CI -1.0 to 1.1), P = 0.90]. No significant treatment benefit was seen for any secondary outcome including muscle mass [adjusted treatment effect -0.3 kg (95%CI -1.0 to 0.4), P = 0.47]. Meta-analysis of angiotensin converting enzyme inhibitor/angiotensin receptor blocker trials showed no clinically important treatment effect for the SPPB [between-group difference -0.1 points (95%CI -0.4 to 0.2)].

CONCLUSIONS

Neither perindopril nor leucine improved physical performance or muscle mass in this trial; meta-analysis did not find evidence of efficacy of either ACE inhibitors or leucine as treatments to improve physical performance.

Resistance exercise as a treatment for sarcopenia: prescription and delivery

Sarcopenia is a generalised skeletal muscle disorder characterised by reduced muscle strength and mass and associated with a range of negative health outcomes. Currently, resistance exercise (RE) is recommended as the first-line treatment for counteracting the deleterious consequences of sarcopenia in older adults. However, whilst there is considerable evidence demonstrating that RE is an effective intervention for improving muscle strength and function in healthy older adults, much less is known about its benefits in older people living with sarcopenia. Furthermore, evidence for its optimal prescription and delivery is very limited and any potential benefits of RE are unlikely to be realised in the absence of an appropriate exercise dose. We provide a summary of the underlying principles of effective RE prescription (specificity, overload and progression) and discuss the main variables (training frequency, exercise selection, exercise intensity, exercise volume and rest periods) that can be manipulated when designing RE programmes. Following this, we propose that an RE programme that consists of two exercise sessions per week and involves a combination of upper- and lower-body exercises performed with a relatively high degree of effort for 1–3 sets of 6–12 repetitions is appropriate as a treatment for sarcopenia. The principles of RE prescription outlined here and the proposed RE programme presented in this paper provide a useful resource for clinicians and exercise practitioners treating older adults with sarcopenia and will also be of value to researchers for standardising approaches to RE interventions in future sarcopenia studies.

A pas de deux of osteoporosis and sarcopenia: osteosarcopenia

The musculoskeletal conditions osteoporosis and sarcopenia are highly prevalent in older adults. Osteoporosis is characterized by low bone mass and microarchitectural deterioration of bone, whereas sarcopenia is identified by the loss of muscle strength, function and mass. Osteoporosis represents a major health problem contributing to millions of fractures worldwide on an annual basis, whereas sarcopenia is associated with a range of adverse physical and metabolic outcomes. They both affect physical and social function, confidence and quality of life as well as contributing to high health-care costs worldwide. Osteosarcopenia is the term given when both conditions occur concomitantly and it has been suggested that interactions between these two conditions may accelerate individual disease progression as co-existence of osteoporosis and sarcopenia is associated with higher morbidity from falls, fracture, disability as well as mortality. In this review, we will outline the epidemiology, pathogenesis and clinical consequences of osteosarcopenia and discuss available management strategies.

Age-Related Declines in Lower Limb Muscle Function are Similar in Power and Endurance Athletes of Both Sexes: A Longitudinal Study of Master Athletes

The age-related decline in muscle function, particularly muscle power, is associated with increased risk of important clinical outcomes. Physical activity is an important determinant of muscle function, and different types of physical activity e.g. power-based versus endurance-based exercise appear to have differential effects on muscle power. Cross-sectional studies suggest that participation in power-based exercise is associated with greater muscle power across adulthood but this has not been investigated longitudinally. We recruited eighty-nine male and female power and endurance master athletes (sprint and distance runners respectively, baseline age 35-90y). Using jumping mechanography, we measured lower limb muscle function during a vertical jump including at least two testing sessions longitudinally over 4.5 ± 2.4y. We examined effects of time, discipline (power/endurance) and sex in addition to two- and three-way interactions using linear mixed-effects models. Peak relative power, relative force and jump height, but not Esslingen Fitness Index (indicating peak power relative to sex and age-matched reference data) declined with time. Peak power, force, height and EFI were greater in power than endurance athletes. There were no sex, discipline or sex*discipline interactions with time for any variable, suggesting that changes were similar over time for athletes of both sexes and disciplines. Advantages in lower limb muscle function in power athletes were maintained with time, in line with previous cross-sectional studies. These results suggest that improvements in lower limb function in less active older individuals following power-based training persist with continued adherence, although this requires further investigation in interventional studies.

Effects of resistance exercise and whey protein supplementation on skeletal muscle strength, mass, physical function, and hormonal and inflammatory biomarkers in healthy active older men: a randomised, double-blind, placebo-controlled trial

PURPOSE

To determine the individual and combined effects of 12 weeks of resistance exercise (RE) and whey protein supplementation on skeletal muscle strength (primary outcome), mass and physical function, and hormonal and inflammatory biomarkers in older adults.

METHODS

Thirty-six healthy older men [(mean±SE) age: 67±1 y; BMI: 25.5±0.4 kg/m²] were randomised to either control (CON; n=9), whey protein (PRO; n=9), RE+control (EX+CON; n=9), or RE+whey protein (EX+PRO; n=9) in a double-blinded fashion. Whole-body RE (2 sets of 8 repetitions and 1 set to volitional failure at 80% 1RM) was performed twice weekly. Supplements (PRO, 25 g whey protein isolate; CON, 23.75 g maltodextrin) were consumed twice daily.

RESULTS

EX+CON and EX+PRO increased leg extension (+19±3 kg and +20±3 kg, respectively) and leg press 1RM (+27±3 kg and +39±2 kg, respectively) greater than the CON and PRO groups (P<0.001, Cohen's d=1.50-1.90). RE (EX+CON and EX+PRO groups pooled) also increased fat-free mass (FFM) (+0.9±0.3 kg) and 6-min walk test distance (+21±5 m) and decreased fat mass (-0.4±0.4 kg), and interleukin-6 (-1.0±0.4 pg/mL) and tumor necrosis factor-alpha concentration (-0.7±0.3 pg/mL) greater than non-exercise (CON and PRO groups pooled; P<0.05, Cohen's f=0.37-0.45). Whey protein supplementation (PRO and EX+PRO groups pooled) increased 4-m gait speed greater than control (CON and EX+CON groups pooled) (+0.08±0.03 m/s; P=0.007, f=0.51).

CONCLUSION

RE increased muscle strength, FFM and physical function, and decreased markers of systemic inflammation in healthy active older men. Whey protein supplementation alone increased gait speed. No synergistic effects were observed. This study was registered at clinicaltrials.gov as NCT03299972.

Relationship between Oral Hypofunction, and Protein Intake: A Cross-Sectional Study in Local Community-Dwelling Adults

Few studies have investigated the relationship between nutritional status and comprehensive assessment of oral hypofunction, especially protein intake-related sarcopenia. Thus, we explored these relationships in a large-scale cross-sectional cohort study using the seven-item evaluation for oral hypofunction and Diet History Questionnaire for nutritional assessment. We used the data from 1004 individuals who participated in the 2019 health survey of the residents of Tarumizu City, Kagoshima Prefecture, Japan for analysis. We found that individuals with oral hypofunction were significantly older with a lower skeletal muscle index. Although there were few foods that had a significant difference between the groups with and without oral hypofunction, the consumption of beans and meats was significantly lower in women and men in the oral hypofunction group, respectively. According to the lower limit of the tentative dietary goal defined in Japan, comprehensive evaluation of oral hypofunction was significantly and independently associated with protein intake in both men and women (odds ratio, 1.70; 95% confidence interval, 1.21-2.35). In conclusion, we found that oral hypofunction was associated with targeted protein intake for sarcopenia and frailty prevention in middle-aged and older community-dwelling adults. Comprehensive evaluation of oral function with intervention in cases of hypofunction could inform clinicians to better prevent sarcopenia.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

We analyzed cross-sectional data from 1209 men and 1208 women aged 40-59 y in the 2011-2014 NHANES. Protein intake per kilogram actual body weight (BW), assessed by two 24-h recalls, was examined as continuous and categorical parameters [low (

RESULTS

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

CONCLUSIONS

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

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Key Words

• NHANES
• appendicular lean mass
• handgrip strength
• middle age
• protein
• sarcopenia

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MESH Headings

• Adult
• Aged
• Body Composition
• Cross-Sectional Studies
• Dietary Proteins/metabolism
• Female
• Hand Strength
• Humans
• Male
• Middle Aged
• Muscle Strength
• Muscle, Skeletal/metabolism
• Nutrition Surveys
• Sarcopenia/metabolism

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Grants

• National Institutes of Health

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Affiliation(s)

Shinyoung Jun Department of Nutrition Science, Purdue University, West Lafayette, IN, USA
Alexandra E Cowan Department of Nutrition Science, Purdue University, West Lafayette, IN, USA
Johanna T Dwyer NIH Office of Dietary Supplements, Bethesda, MD, USA Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, USA
Wayne W Campbell Department of Nutrition Science, Purdue University, West Lafayette, IN, USA
Anna E Thalacker-Mercer Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
Jaime J Gahche NIH Office of Dietary Supplements, Bethesda, MD, USA
Regan L Bailey Department of Nutrition Science, Purdue University, West Lafayette, IN, USA

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Understanding the gut microbiota and sarcopenia: a systematic review

BACKGROUND

Gut microbiota dysbiosis and sarcopenia commonly occur in the elderly. Although the concept of the gut-muscle axis has been raised, the casual relationship is still unclear. This systematic review analyses the current evidence of gut microbiota effects on muscle/sarcopenia.

METHODS

A systematic review was performed in PubMed, Embase, Web of Science, and The Cochrane Library databases using the keywords (microbiota* OR microbiome*) AND (sarcopen* OR muscle). Studies reporting the alterations of gut microbiota and muscle/physical performance were analysed.

RESULTS

A total of 26 pre-clinical and 10 clinical studies were included. For animal studies, three revealed age-related changes and relationships between gut microbiota and muscle. Three studies focused on muscle characteristics of germ-free mice. Seventy-five per cent of eight faecal microbiota transplantation studies showed that the recipient mice successfully replicated the muscle phenotype of donors. There were positive effects on muscle from seven probiotics, two prebiotics, and short-chain fatty acids (SCFAs). Ten studies investigated on other dietary supplements, antibiotics, exercise, and food withdrawal that affected both muscle and gut microbiota. Twelve studies explored the potential mechanisms of the gut-muscle axis. For clinical studies, 6 studies recruited 676 elderly people (72.8 ± 5.6 years, 57.8% female), while 4 studies focused on 244 young adults (29.7 ± 7.8 years, 55.4% female). The associations of gut microbiota and muscle had been shown in four observational studies. Probiotics, prebiotics, synbiotics, fermented milk, caloric restriction, and exercise in six studies displayed inconsistent effects on muscle mass, function, and gut microbiota.

CONCLUSIONS

Altering the gut microbiota through bacteria depletion, faecal transplantation, and various supplements was shown to directly affect muscle phenotypes. Probiotics, prebiotics, SCFAs, and bacterial products are potential novel therapies to enhance muscle mass and physical performance. Lactobacillus and Bifidobacterium strains restored age-related muscle loss. Potential mechanisms of microbiome modulating muscle mainly include protein, energy, lipid, and glucose metabolism, inflammation level, neuromuscular junction, and mitochondrial function. The role of the gut microbiota in the development of muscle loss during aging is a crucial area that requires further studies for translation to patients.

Between-study differences in grip strength: a comparison of Norwegian and Russian adults aged 40-69 years

BACKGROUND

Identifying individuals with low grip strength is an initial step in many operational definitions of sarcopenia. As evidence indicates that contemporaneous Russian populations may have lower mean levels of grip strength than other populations in northern Europe, we aimed to: compare grip strength in Russian and Norwegian populations by age and sex; investigate whether height, body mass index, education, smoking status, alcohol use and health status explain observed differences and; examine implications for case-finding low muscle strength.

METHODS

We used harmonized cross-sectional data on grip strength and covariates for participants aged 40-69 years from the Russian Know Your Heart study (KYH) (n = 3833) and the seventh survey of the Norwegian Tromsø Study (n = 5598). Maximum grip strength (kg) was assessed using the same protocol and device in both studies. Grip strength by age, sex and study was modelled using linear regression and between-study differences were predicted from these models. Sex-specific age-standardized differences in grip strength and in prevalence of low muscle strength were estimated using the European population standard of 2013.

RESULTS

Normal ranges of maximum grip strength in both studies combined were 33.8 to 67.0 kg in men and 18.7 to 40.1 kg in women. Mean grip strength was higher among Tromsø than KYH study participants and this difference did not vary markedly by age or sex. Adjustment for covariates, most notably height, attenuated between-study differences but these differences were still evident at younger ages. For example, estimated between-study differences in mean grip strength in fully adjusted models were 2.2 kg [95% confidence interval (CI) 1.4, 3.1] at 40 years and 1.0 kg (95% CI 0.5, 1.5) at 65 years in men (age × study interaction P = 0.09) and 1.1 kg (95% CI 0.4, 1.9) at age 40 years and -0.2 kg (95% CI -0.7, 0.3) at 65 years in women (age × study interaction P < 0.01).

CONCLUSIONS

We found between-study differences in mean grip strength that are likely to translate into greater future risk of sarcopenia and poorer prospects of healthy ageing for Russian than Norwegian study participants. For example, the average Russian participant had a similar level of grip strength to a Norwegian participant 7 years older. Our findings suggest these differences may have their origins in childhood highlighting the need to consider interventions in early life to prevent sarcopenia.

Self-Reported and Performance-Based Evaluations of Functional Status in Older Women With Breast Cancer

OBJECTIVES

To evaluate self-reported and performance-based functional status (FS) in older women with breast cancer according to stage and time of visit during treatment.

SAMPLE & SETTING

72 women with breast cancer aged 78 years or older and receiving any type of treatment at a midwestern outpatient clinic.

METHODS & VARIABLES

FS was evaluated using grip strength, the Index of Activities of Daily Living (ADLs), the instrumental ADLs (IADLs) scale, and the Timed Up and Go Test (TUGT). Mixed models were fit for grip strength and the TUGT, and generalized estimating equations were used to fit binary logistic regressions for the Index of ADLs and the IADLs scale. Continuous FS outcomes were evaluated using means and standard deviations.

RESULTS

Cancer stage and time of visit did not affect self-reported or performance-based FS scores. Most participants were considered independent on the Index of ADLs, the IADLs scale, and the TUGT, which did not change significantly between visits. Self-reported measures revealed less impairment.

IMPLICATIONS FOR NURSING

Monitoring FS using self-reported and performance-based measures can ensure that older patients receive timely support.

High Intensity Interval Training (HIIT) as a Potential Countermeasure for Phenotypic Characteristics of Sarcopenia: A Scoping Review

Background: Sarcopenia is defined as a progressive and generalized loss of skeletal muscle quantity and function associated predominantly with aging. Physical activity appears the most promising intervention to attenuate sarcopenia, yet physical activity guidelines are rarely met. In recent years high intensity interval training (HIIT) has garnered interested in athletic populations, clinical populations, and general population alike. There is emerging evidence of the efficacy of HIIT in the young old (i.e. seventh decade of life), yet data concerning the oldest old (i.e., ninth decade of life onwards), and those diagnosed with sarcopenic are sparse. Objectives: In this scoping review of the literature, we aggregated information regarding HIIT as a potential intervention to attenuate phenotypic characteristics of sarcopenia. Eligibility Criteria: Original investigations concerning the impact of HIIT on muscle function, muscle quantity or quality, and physical performance in older individuals (mean age ≥60 years of age) were considered. Sources of Evidence: Five electronic databases (Medline, EMBASE, Web of Science, Scopus, and the Cochrane Central Register of Controlled Trials [CENTRAL]) were searched. Methods: A scoping review was conducted using the Arksey and O'Malley methodological framework (2005). Review selection and characterization were performed by two independent reviewers using pretested forms. Results: Authors reviewed 1,063 titles and abstracts for inclusion with 74 selected for full text review. Thirty-two studies were analyzed. Twenty-seven studies had a mean participant age in the 60s, two in the 70s, and three in the 80s. There were 20 studies which examined the effect of HIIT on muscle function, 22 which examined muscle quantity, and 12 which examined physical performance. HIIT was generally effective in Improving muscle function and physical performance compared to non-exercised controls, moderate intensity continuous training, or pre-HIIT (study design-dependent), with more ambiguity concerning muscle quantity. Conclusions: Most studies presented herein utilized outcome measures defined by the European Working Group on Sarcopenia in Older People (EWGSOP). However, there are too few studies investigating any form of HIIT in the oldest old (i.e., ≥80 years of age), or those already sarcopenic. Therefore, more intervention studies are needed in this population.

Resistance exercise training at different loads in frail and healthy older adults: A randomised feasibility trial

Objectives

This trial aimed to determine the feasibility of recruitment, retention, adherence, and safety of a resistance training (RT) intervention to skeletal muscle failure in both frail and non-frail older adults.

Design

An 8-week randomised feasibility trial.

Setting and participants

Older adults, with and without frailty, recruited from both clinics and community.

Methods

Recruitment was based on the number of participants enrolled from those provided with a Patient Information Sheet (PIS). Retention was based on the number of participants who completed the trial. Adherence was based on the number of RT sessions attended out of 16. Outcomes included frailty (Fried criteria), muscle strength (maximal voluntary contraction), functional abilities (Short Physical Performance battery), quality of life (EQ-5D-5L), activities of daily living (LIADL) and safety (diary).

Results

Recruitment target (n = 60) was achieved within 15 months, 58 were randomised to high (n = 30) or low repetition-load (n = 28) groups. Mean age of participants was 72 years (range 65–93). Adherence and retention rate for the RT intervention was ≥70%. There was one serious adverse experience due to the RT intervention. There were no differences (P > 0.05) in effects of RT on outcome variables between low and high repetition-load groups.

Conclusions and implications

Recruitment of frail people was challenging. Older adults performing supervised RT to skeletal muscle failure was feasible and safe, with appropriate caution, and the repetition-load did not appear to influence its efficacy. Future research into the effectiveness of this simplified model of RT is warranted.

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Resistance exercise is the most effective way to increase muscle mass.

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This is particularly important in older adults.

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Recruitment of older adults, particularly with frailty, is challenging.

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We found recruitment of older adults feasible, but less so for those with frailty.

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The load for exercise did not appear to influence efficacy of exercise.

Health Recognition Algorithm for Sports Training Based on Bi-GRU Neural Networks

The healthcare benefits associated with regular physical activity recognition and monitoring have been considered in several research studies. Regular recognition and monitoring of health status can potentially assist in managing and reducing the risk of many diseases such as cardiovascular disease, diabetes, and obesity. Using healthcare equipment in hospitals, people can conduct regular physical examinations to check their health status. However, most of the time, it is difficult to reach a specific medical environment and use special medical equipment. In this paper, a deep learning framework based on the bidirectional gated recurrent unit for health status recognition is implemented to improve the accuracy by making full use of the information provided by smartphone acceleration sensors. A model based on a bidirectional gated recurrent unit is constructed to describe the relationship between input acceleration signals and output information through a gating approach. Therefore, it can automatically detect the health status of the sportsman as healthy, subhealthy, and unhealthy. Finally, the practical data collected from an athlete have been used to evaluate the recognition performance of the system. Results show that the proposed methodology can predicate the sports health status accurately.

Feasibility and Acceptability of Home-Based Exercise Snacking and Tai Chi Snacking Delivered Remotely to Self-Isolating Older Adults During COVID-19

The purpose of this study was to examine the feasibility and acceptability of remotely delivered, home-based exercise programs on physical function and well-being in self-isolating older adults during the COVID-19 pandemic. In a four-arm randomized controlled trial, 63 participants (aged 65 years and older) were allocated to one of three home-based daily (2 × 10-min) exercise interventions (exercise snacking, tai chi snacking, and combination) or control (UK National Health Service Web pages). Functional assessments were conducted via video call at baseline and 4-week follow-up. A web-based survey assessed the acceptability of each exercise program and secondary psychological/well-being outcomes. Ecological momentary assessment data, collected in Weeks 1 and 4, explored feeling states as antecedents and consequences of exercise. All intervention groups saw increased physical function at follow-up and displayed good adherence with exercise snacking considered the most acceptable program. Multilevel models revealed reciprocal associations between feelings of energy and exercise engagement. Further studies are needed with larger, more diverse demographic samples.

Transcriptomic meta-analysis of disuse muscle atrophy vs. resistance exercise-induced hypertrophy in young and older humans

BACKGROUND

Skeletal muscle atrophy manifests across numerous diseases; however, the extent of similarities/differences in causal mechanisms between atrophying conditions in unclear. Ageing and disuse represent two of the most prevalent and costly atrophic conditions, with resistance exercise training (RET) being the most effective lifestyle countermeasure. We employed gene-level and network-level meta-analyses to contrast transcriptomic signatures of disuse and RET, plus young and older RET to establish a consensus on the molecular features of, and therapeutic targets against, muscle atrophy in conditions of high socio-economic relevance.

METHODS

Integrated gene-level and network-level meta-analysis was performed on publicly available microarray data sets generated from young (18-35 years) m. vastus lateralis muscle subjected to disuse (unilateral limb immobilization or bed rest) lasting ≥7 days or RET lasting ≥3 weeks, and resistance-trained older (≥60 years) muscle.

RESULTS

Disuse and RET displayed predominantly separate transcriptional responses, and transcripts altered across conditions were mostly unidirectional. However, disuse and RET induced directly inverted expression profiles for mitochondrial function and translation regulation genes, with COX4I1, ENDOG, GOT2, MRPL12, and NDUFV2, the central hub components of altered mitochondrial networks, and ZMYND11, a hub gene of altered translation regulation. A substantial number of genes (n = 140) up-regulated post-RET in younger muscle were not similarly up-regulated in older muscle, with young muscle displaying a more pronounced extracellular matrix (ECM) and immune/inflammatory gene expression response. Both young and older muscle exhibited similar RET-induced ubiquitination/RNA processing gene signatures with associated PWP1, PSMB1, and RAF1 hub genes.

CONCLUSIONS

Despite limited opposing gene profiles, transcriptional signatures of disuse are not simply the converse of RET. Thus, the mechanisms of unloading cannot be derived from studying muscle loading alone and provides a molecular basis for understanding why RET fails to target all transcriptional features of disuse. Loss of RET-induced ECM mechanotransduction and inflammatory profiles might also contribute to suboptimal ageing muscle adaptations to RET. Disuse and age-dependent molecular candidates further establish a framework for understanding and treating disuse/ageing atrophy.

Mouse models of sarcopenia: classification and evaluation

Sarcopenia is a progressive and widespread skeletal muscle disease that is related to an increased possibility of adverse consequences such as falls, fractures, physical disabilities and death, and its risk increases with age. With the deepening of the understanding of sarcopenia, the disease has become a major clinical disease of the elderly and a key challenge of healthy ageing. However, the exact molecular mechanism of this disease is still unclear, and the selection of treatment strategies and the evaluation of its effect are not the same. Most importantly, the early symptoms of this disease are not obvious and are easy to ignore. In addition, the clinical manifestations of each patient are not exactly the same, which makes it difficult to effectively study the progression of sarcopenia. Therefore, it is necessary to develop and use animal models to understand the pathophysiology of sarcopenia and develop therapeutic strategies. This paper reviews the mouse models that can be used in the study of sarcopenia, including ageing models, genetically engineered models, hindlimb suspension models, chemical induction models, denervation models, and immobilization models; analyses their advantages and disadvantages and application scope; and finally summarizes the evaluation of sarcopenia in mouse models.

Sex Differences in Adaptations in Muscle Strength and Size Following Resistance Training in Older Adults: A Systematic Review and Meta-analysis

BACKGROUND

Reductions in muscle size and strength occur with aging. These changes can be mitigated by participation in resistance training. At present, it is unknown if sex contributes to differences in adaptation to resistance training in older adults.

OBJECTIVE

The aim of this systematic review was to determine if sex differences are apparent in adaptations to resistance training in older adults.

DESIGN

Systematic review with meta-analysis.

DATA SOURCES

Web of Science; Science Direct; SPORTDiscus; CINAHL; and MEDLINE were searched from inception to June 2020.

ELIGIBILITY CRITERIA

Studies where males and females older than 50 years of age performed identical resistance training interventions and had outcome measures of muscle strength or size.

RESULTS

We initially screened 5337 studies. 30 studies (with 41 comparison groups) were included in our review (1410 participants; 651 males, 759 females). Mean study quality was 14.7/29 on a modified Downs and Black checklist, considered moderate quality. Females gained more relative lower-body strength than males (g = - 0.21 [95% CI - 0.33, - 0.10], p = 0.0003) but there were no differences in relative change for upper-body strength (g = - 0.29 [95% CI - 0.62, 0.04], p = 0.08) or relative muscle size (g = 0.10 [95% CI - 0.04, 0.23], p = 0.16). Males gained more absolute upper-body strength (g = 0.48 [95% CI 0.09, 0.88], p = 0.016), absolute lower-body strength (g = 0.33 [95% CI 0.19, 0.47], p < 0.0001), and absolute muscle size (g = 0.45 [95% CI 0.23, 0.66], p < 0.0001).

CONCLUSION

Our results indicate that sex differences in adaptations to resistance training are apparent in older adults. However, it is evident that the interpretation of sex-dependent adaptations to resistance training is heavily influenced by the presentation of the results in either an absolute or relative context.

STUDY REGISTRATION

Open Science Framework (osf.io/afn3y/).

Micronutrients and sarcopenia: current perspectives

Sarcopenia, a skeletal muscle disorder that is characterised by loss of muscle strength and mass, is common in older populations and associated with poorer health outcomes. Although the individual and economic costs of sarcopenia are widely recognised, current understanding of its pathophysiology is incomplete, limiting efforts to translate research evidence into effective preventive and treatment strategies. While nutrition is a key field of sarcopenia research, the role of differences in habitual diets, and the effectiveness of dietary change as a prevention or treatment strategy, is uncertain. There is a growing evidence base that links low micronutrient intakes to sarcopenia risk and/or its components (low muscle strength and mass, impaired physical performance), although there remain many gaps in understanding. There is some consistency in findings across studies highlighting potential roles for antioxidant nutrients, B vitamins and magnesium; however, the evidence is largely observational and from cross-sectional studies, often describing associations with different muscle outcomes. As low intakes of some micronutrients are common in older populations, there is a need for new research, particularly from well-characterised prospective cohorts, to improve the understanding of their role and importance in the aetiology of sarcopenia and to generate the evidence needed to inform dietary guidelines to promote muscle health.

Higher Branched-Chain Amino Acid Intake Is Associated with Handgrip Strength among Korean Older Adults

Sarcopenia is a disease of old age characterized by decreased muscle mass and strength. Branched-chain amino acids (BCAAs) promote muscle mass synthesis and increase muscle strength. We aimed to develop a dietary amino acid database and to examine the association between BCAA intake and handgrip strength in Korean older adults. Data from the Korea National Health and Nutrition Examination Survey 2014–2018 were used. Overall, 4852 participants aged ≥65 years were included in the study. Demographic, lifestyle, and health data were obtained through interviews and questionnaires. The 24-h recall method was used to assess dietary intake. An amino acid database was established using the 9th revision of the Korean Standard Food Composition Table. The mean handgrip strength was estimated from triplicate measurements obtained using the dominant hand. Multivariable linear regression analysis was performed to assess the association between BCAA intake and handgrip strength. Grains greatly contributed to amino acid intake; however, a significant negative association was observed between handgrip strength and increased BCAA intake through grains. In the fully adjusted model, leucine intake and handgrip strength showed a positive association. Thus, consuming BCAAs (especially leucine) via a variety of food sources can help maintain muscle health in older people.

The effect of young and old ex vivo human serum on cellular protein synthesis and growth in an in vitro model of aging

In vitro models of muscle aging are useful for understanding mechanisms of age-related muscle loss and aiding the development of targeted therapies. To investigate mechanisms of age-related muscle loss in vitro utilizing ex vivo human serum, fasted blood samples were obtained from four old (72 ± 1 yr) and four young (26 ± 3 yr) men. Older individuals had elevated levels of plasma CRP, IL-6, HOMA-IR, and lower concentric peak torque and work-per-repetition compared with young participants (P < 0.05). C2C12 myotubes were serum and amino acid starved for 1 h and conditioned with human serum (10%) for 4 h or 24 h. After 4 h, C2C12 cells were treated with 5 mM leucine for 30 min. Muscle protein synthesis (MPS) was determined through the surface sensing of translation (SUnSET) technique and regulatory signaling pathways were measured via Western blot. Myotube diameter was significantly reduced in myotubes treated with serum from old, in comparison to young donors (84%, P < 0.001). MPS was reduced in myotubes treated with old donor serum, compared with young serum before leucine treatment (32%, P < 0.01). MPS and the phosphorylation of Akt, p70S6K, and eEF2 were increased in myotubes treated with young serum in response to leucine treatment, with a blunted response identified in cells treated with old serum (P < 0.05). Muscle protein breakdown signaling pathways did not differ between groups. In summary, we show that myotubes conditioned with serum from older individuals had decreased myotube diameter and MPS compared with younger individuals, potentially driven by low-grade systemic inflammation.

Muscle Performance Changes with Age in Active Women

The purpose of this study was to examine age-related differences in muscle performance in women divided into young (YW, 20–39 years, n = 29) middle-aged (MAW, 40–59 years, n = 33), and older (OW, ≥60 years, n = 40) age groups. Methods: Hand grip strength, vertical jump performance, and knee extensor (KE) strength (0 deg/s, 60 deg/s, and 240 deg/s), speed of movement (SoM; at 1 Nm, 20%, 40%, and 60% isometric strength), and endurance (30-repetition test at 60 degs/s and 240 deg/s) were assessed. Computed tomography-acquired muscle cross-sectional area (mCSA) was measured and included to determine specific strength (KE strength/mCSA). Results: Hand grip strength was similar across groups, while jump performance declined with age (YW and MAW > OW, p < 0.001). KE strength declined significantly with age (all conditions p < 0.01), while specific strength was similar across groups. SoM was significantly higher for YW and MAW compared to OW (both p < 0.01). An age × velocity interaction revealed YW KE endurance was similar between conditions, whereas MAW and OW displayed significantly better endurance during the 60 deg/s condition. OW displayed impaired KE endurance at 240 deg/s (vs. YW and MAW, p < 0.01) but improved at 60 deg/s (vs. YW, p < 0.01). Dynamic torque decline increased with age (YW < OW, p = 0.03) and was associated with intramuscular adipose tissue (r = 0.21, p = 0.04). Conclusions: Performance declines were most evident among OW, but few performance deficits had emerged in MAW. Interestingly, strength declines disappeared after normalizing to mCSA and endurance appears to be velocity-dependent.

Association of Oral Hypofunction with Frailty, Sarcopenia, and Mild Cognitive Impairment: A Cross-Sectional Study of Community-Dwelling Japanese Older Adults

Oral hypofunction is a new concept that addresses the oral function of older adults. Few studies have investigated the relationship between oral hypofunction and general health conditions such as frailty, sarcopenia, and mild cognitive impairment. This paper explores these relationships in a large-scale, cross-sectional cohort study. The relationships of oral hypofunction with frailty, sarcopenia, and mild cognitive impairment were examined using data from 832 individuals who participated in the 2018 health survey of the residents of Tarumizu City, Kagoshima Prefecture, Japan. Individuals with frailty, sarcopenia, and mild cognitive impairment had significantly higher rates of oral hypofunction. Frailty was independently associated with deterioration of the swallowing function (odds ratio 2.56; 95% confidence interval, 1.26-5.20), and mild cognitive impairment was independently associated with reduced occlusal force (odds ratio 1.48; 95% confidence interval, 1.05-2.08) and decreased tongue pressure (odds ratio 1.77; 95% confidence interval, 1.28-2.43). There was no independent association found between sarcopenia and oral function. In conclusion, early intervention for related factors such as deterioration of the swallowing function in frailty, reduced occlusal force, and decreased tongue pressure in mild cognitive impairment could lead to the prevention of general hypofunction in older adults.

Functional autonomy and sarcopenia markers in women over 55 years of age

Introduction: Some parameters used to diagnose sarcopenia and functional autonomy disorders can lead to interpretation and classification errors. Objective: To analyze sarcopenia markers and their relationship with the strength and gait of physically active older women aged between 55 and 76 years. Materials and Methods: Analytical observational study conducted in 178 physically active Colombian women who were distributed in two age groups (group 1: 55-66 years, n=98, and group 2: 67-76 years, n=80). A multiple linear regression model was used to establish possible correlations between strength and gait indicators (dependent variables) and body composition (independent variables). Results: Fat mass and appendicular mass (appendicular lean/height2(kg/m2)) explained power variance in the lower limbs in group 1 (G1) (SJ: p=0.001, R2=0.56; CMJ: p=0.001, R2=0.51; CMJAS: R2=0.60, p=0.001). Similar results were observed in group 2 (G2) (SJ: R2=0.32, DW1=2.14; CMJ: R2=0.51, DW2=2.38; CMJAS: R2=0.41, DW3=2.56). Furthermore, fat mass explained variance in gait pattern in G1 and G2 differently (G1: p=-0.006; R2=20%; G2: p=-0.001; R2=29%). Conclusion: Recording fat and appendicular mass allow studying negative changes in lower limb strength and their effect on gait pattern, as well as identifying the type of sarcopenia and functional autonomy disorders in physically active Colombian women aged 55 to 76 years.

The longitudinal associations between bone mineral density and appendicular skeletal muscle mass in Chinese community-dwelling middle aged and elderly men

Background

The present study aimed to investigate longitudinal associations between bone mineral densities (BMDs) and appendicular skeletal muscle (ASM) mass in different regions of the body using three different indicators, in Chinese community-dwelling middle-aged and elderly men.

Methods

A total of 1,343 men aged ≥ 40 years from a Chinese community were assessed at baseline (2014-2016), one-year follow-up (2016-2017; n = 648), two-year follow-up (2017-2018; n = 407), and three-year follow up (2018-2019; n = 208). At all the four time-points, measurements included ASM mass and BMDs for all regions of the body using dual-energy X-ray absorptiometry. A questionnaire was completed by patients and biochemical markers were assessed. We applied three different indicators to define ASM mass or lean mass respectively, including the appendicular skeletal muscle index (ASM adjusted by height, ASMI, according to the Asian Working Group for Sarcopenia), skeletal muscle index (ASM adjusted by weight, SMI, according to the International Working Group on Sarcopenia), and the appendicular skeletal muscle/body mass index (ratio of ASM and Body mass index (BMI), ASM/BMI, according to the Foundation for the National Institutes of Health). After adjusting for potential confounders, the generalized additive mixed model (GAMM) was used to analyze the trend in ASM mass over time, and to test the association between ASM mass and regional and whole-body BMDs.

Results

The incidence of low lean mass was 8.2% defined by ASMI, 16.3% defined by SMI, and 8.3% defined by ASM/BMI. There was a linear relationship between BMDs and ASM mass, and ASMI, ASM/BMI, and SMI gradually decreased with time. After adjusting for covariances, GAMM analysis determined longitudinal associations between BMDs and ASM mass by three indicators respectively: the skull BMD was negatively associated with ASM mass. For each unit increase in skull BMD, ASMI decreased by 0.28 kg/m² (95% confidence interval (CI) [-0.39 to -0.16]), ASM/BMI decreased by 0.02 m² (95% CI [-0.03 to -0.00]), and SMI decreased by 0.01% (95% CI[-0.01 to -0.00]). The remaining parameters (including whole-body mean BMD, thoracic spinal BMD, lumbar spinal BMD, hip BMD, femoral neck BMD, pelvic BMD, left arm BMD, right arm BMD, left leg BMD, right leg BMD) were positively correlated with ASM mass. The ASMI increased by 3.07 kg/m²for each unit increase in the femoral neck BMD (95% CI [2.31-3.84]). The ASM/BMI increased by 0.22 m²for each unit increase in the left arm BMD (95% CI [0.12-0.33]), and the SMI increased by 0.05% per unit increase in the left arm BMD (95% CI [0.02-0.08]).

Conclusions

Compared to ASMI and ASM/BMI, SMI was more sensitive to screen for the low lean mass. Skull BMD was negatively associated with ASM mass, while BMDs throughout the rest of the body were positively correlated with ASM mass among the middle-aged and elderly Chinese men.

The effect of short-term exercise prehabilitation on skeletal muscle protein synthesis and atrophy during bed rest in older men

BACKGROUND

Poor recovery from periods of disuse accelerates age-related muscle loss, predisposing individuals to the development of secondary adverse health outcomes. Exercise prior to disuse (prehabilitation) may prevent muscle deterioration during subsequent unloading. The present study aimed to investigate the effect of short-term resistance exercise training (RET) prehabilitation on muscle morphology and regulatory mechanisms during 5 days of bed rest in older men.

METHODS

Ten healthy older men aged 65-80 years underwent four bouts of high-volume unilateral leg RET over 7 days prior to 5 days of inpatient bed rest. Physical activity and step-count were monitored over the course of RET prehabilitation and bed rest, whilst dietary intake was recorded throughout. Prior to and following bed rest, quadriceps cross-sectional area (CSA), and hormone/lipid profiles were determined. Serial muscle biopsies and dual-stable isotope tracers were used to determine integrated myofibrillar protein synthesis (iMyoPS) over RET prehabilitation and bed rest phases, and acute postabsorptive and postprandial myofibrillar protein synthesis (aMyoPS) rates at the end of bed rest.

RESULTS

During bed rest, daily step-count and light and moderate physical activity time decreased, whilst sedentary time increased when compared with habitual levels (P < 0.001 for all). Dietary protein and fibre intake during bed rest were lower than habitual values (P < 0.01 for both). iMyoPS rates were significantly greater in the exercised leg (EX) compared with the non-exercised control leg (CTL) over prehabilitation (1.76 ± 0.37%/day vs. 1.36 ± 0.18%/day, respectively; P = 0.007). iMyoPS rates decreased similarly in EX and CTL during bed rest (CTL, 1.07 ± 0.22%/day; EX, 1.30 ± 0.38%/day; P = 0.037 and 0.002, respectively). Postprandial aMyoPS rates increased above postabsorptive values in EX only (P = 0.018), with no difference in delta postprandial aMyoPS stimulation between legs. Quadriceps CSA at 40%, 60%, and 80% of muscle length decreased significantly in EX and CTL over bed rest (0.69%, 3.5%, and 2.8%, respectively; P < 0.01 for all), with no differences between legs. No differences in fibre-type CSA were observed between legs or with bed rest. Plasma insulin and serum lipids did not change with bed rest.

CONCLUSIONS

Short-term resistance exercise prehabilitation augmented iMyoPS rates in older men but did not offset the relative decline in iMyoPS and muscle mass during bed rest.

Skeletal Muscle and Metabolic Health: How Do We Increase Muscle Mass and Function in People with Type 2 Diabetes?

BACKGROUND

Whilst skeletal muscles' primary role is allowing movement, it has important metabolic roles, including in glycemic control. Indeed, evidence indicates that low muscle mass and function are associated with an increased risk of type 2 diabetes, highlighting its importance in the development of metabolic disease.

METHODS

In this mini-review, we detail the evidence highlighting the importance of muscle in type 2 diabetes and the efficacy of resistance exercise in improving glycemic control alongside our approach to increase uptake of such exercise in people with type 2 diabetes. This summary is based in the authors' knowledge of the filed supplemented by a Pubmed search using the terms "muscle," "glycemic control," "HbA1c," "type 2 diabetes," and "resistance exercise."

RESULTS

The main strategy to increases muscle mass is to perform resistance exercise and, although the quality of evidence is low, such exercise appears effective in reducing Glycated Haemoglobin (HbA1c) in people with type 2 diabetes. However, to increase participation we need to improve our understanding of barriers and facilitators to such exercise. Current data indicate that barriers are similar to those reported for aerobic exercise, with additional resistance exercise specific barriers of looking to muscular, increase risk of cardiovascular event, having access to specialized equipment and knowledge of how to use it.

CONCLUSIONS

The development of simple resistance exercises that can be performed anywhere, that use little or no equipment and are effective in reducing HbA1c will be, in our opinion, key to increasing the number of people with type 2 diabetes performing resistance exercise.

Links Between Testosterone, Oestrogen, and the Growth Hormone/Insulin-Like Growth Factor Axis and Resistance Exercise Muscle Adaptations

Maintenance of skeletal muscle mass throughout the life course is key for the regulation of health, with physical activity a critical component of this, in part, due to its influence upon key hormones such as testosterone, estrogen, growth hormone (GH), and insulin-like growth factor (IGF). Despite the importance of these hormones for the regulation of skeletal muscle mass in response to different types of exercise, their interaction with the processes controlling muscle mass remain unclear. This review presents evidence on the importance of these hormones in the regulation of skeletal muscle mass and their responses, and involvement in muscle adaptation to resistance exercise. Highlighting the key role testosterone plays as a primary anabolic hormone in muscle adaptation following exercise training, through its interaction with anabolic signaling pathways and other hormones via the androgen receptor (AR), this review also describes the potential importance of fluctuations in other hormones such as GH and IGF-1 in concert with dietary amino acid availability; and the role of estrogen, under the influence of the menstrual cycle and menopause, being especially important in adaptive exercise responses in women. Finally, the downstream mechanisms by which these hormones impact regulation of muscle protein turnover (synthesis and breakdown), and thus muscle mass are discussed. Advances in our understanding of hormones that impact protein turnover throughout life offers great relevance, not just for athletes, but also for the general and clinical populations alike.

Age-related degeneration of lumbar muscle morphology in healthy younger versus older men

AIM

The aim of this study was to evaluate age-related changes in lumbar paravertebral muscle (LPM) morphology in healthy younger and older adult men.

METHODS

T2-weighted axial MRI of the lumbar spine were obtained for 12 healthy older (67.3 ± 6.0 years) and younger (24.7 ± 3.1 years) men. Normalised muscle volume (NMV) and muscle fat infiltrate (MFI) were determined bilaterally for the psoas (PS), quadratus lumborum (QL), erector spinae (ES) and multifidus (MF). MANOVA was used to compare NMV and MFI between age groups. Follow-up ANOVA compared NMV and MFI for each muscle between age groups, with physical activity (PA) as a covariate. Stepwise regression was used to explore the association between muscle morphology.

RESULTS

NMV of the ES and QL were significantly lower in the older group (OG) (p = 0.040 and p < 0.001, respectively). MFI across all muscles was significantly greater in the OG (p < 0.001). PA did not moderate the relationship between aging and muscle degeneration. Non-dominant handgrip strength was associated with NMV (p = 0.003).

CONCLUSIONS

Age-related atrophy is muscle specific in the lumbar spine; changes in lumbar musculature is independent of PA, handgrip strength may reflect morphological changes in the postural muscles with age. This study supports establishing effective targeted exercise interventions in the lumbar musculature.

Association between dietary branched-chain amino acid intake and skeletal muscle mass index among Korean adults: Interaction with obesity

BACKGROUND/OBJECTIVES

The branched-chain amino acids (BCAA), including isoleucine, leucine, and valine, promote muscle protein synthesis. However, obesity may interfere with protein synthesis by dysregulating mitochondrial function in the muscles. This study aimed to examine the association between dietary intake levels of BCAA and skeletal muscle mass index (SMI) in middle-aged participants, and the effect of obesity/abdominal obesity on this association.

SUBJECTS/METHODS

The data of 3,966 men and women aged 50-64 years who participated in the 2008-2011 Korea National Health and Nutrition Examination Survey were analyzed. Intake levels of energy-adjusted dietary amino acids were obtained using a 24-hour dietary recall. SMI was calculated by dividing the appendicular skeletal muscle mass by body weight (kg) and multiplying the result by 100%. Multivariable general linear models were used to analyze the association of dietary BCAA intake levels with SMI.

RESULTS

The beneficial effects of energy-adjusted dietary BCAA intakes on SMI were greater in the non-obesity/non-abdominal obesity groups; however, no significant associations were observed in the obesity/abdominal obesity groups (P > 0.05).

CONCLUSIONS

Healthy weight and sufficient intake of dietary BCAA are recommended to maintain muscle mass.