Perspective: Protein and exercise for frailty and sarcopenia: still learning

The Effects of Muscle Cell Aging on Myogenesis

The process of myogenesis gradually deteriorates as the skeletal muscle ages, contributing to muscle mass loss. The aim of this study is to investigate the effect of senescence/aging on skeletal myogenesis, in vitro. A model of multiple cell divisions of C2C12 myoblasts was used to replicate cell senescence. Control and aged myoblasts were investigated during myogenesis, i.e., at days 0, 2, and 6of differentiation. SA-β-gal activity and comet assay were used as markers of aging and DNA damage. Flow cytometry was performed to characterize potential differences in cell cycle between control and aged cells. Alterations in the mRNA and/or protein expression of myogenic regulatory factors (MRFs), IGF-1 isoforms, apoptotic, atrophy, inflammatory, metabolic and aging-related factors were evaluated. Compared with the control cells, aged myoblasts exhibited G0/G1 cell cycle arrest, DNA damage, increased SA-β-gal activity, and increased expression of aging-related factors p16 and p21 during differentiation. Moreover, aged myoblasts showed a reduction in the expression of MRFs and metabolic/anabolic factors, along with an increased expression of apoptotic, atrophy and inflammatory factors. A diminished differentiation capacity characterized the aged myoblasts which, in combination with the induction of apoptotic and atrophy factors, indicated a disrupted myogenic lineage in the senescent muscle cells.

Age-Related Decline in Vertical Jumping Performance in Masters Track and Field Athletes: Concomitant Influence of Body Composition

Vertical jumping power declines with advancing age, which is theoretically explicable by loss of muscle mass and increases in body fat. However, the results of previous cross-sectional studies remain inconsistent on these relationships. The present study included 256 masters athletes who competed at the 2018 track and field world championships in Málaga, Spain. We assessed body composition with bioelectrical impedance (Inbody S10) and vertical jumping power with a Leonardo ground reaction force platform. Relationships between age, jumping power, and body composition were analyzed by correlation and regression analyses. Hierarchical multiple regression analysis was used to evaluate effects of each factor on vertical jumping power. Age-related rates of decreases in maximal power and jump height were similar between male and female athletes. Percent fat-free mass and percent body fat were negatively and positively, respectively, associated with age in masters athletes and were comparable to those previously observed in the general population. Moreover, these effects in body composition can, to a great extent, explain the age-related decline in jumping power, an effect that seems at least partly independent of age. Finally, the multiple regression model to determine independent predictors of vertical jump performance yielded an overall R² value of 0.75 with the inclusion of (1) athletic specialization in power events, (2) percent fat-free mass, and (3) phase angle. However, partial regression yielded significant effects of age, but not gender, on peak power, even when adjusting for athletic specialization, percent fat-free mass, and phase angle. We concluded that loss of skeletal muscle mass and changes in bio-impedance phase angle are important contributors to the age-related reduction in anaerobic power, even in adults who maintain high levels of physical activity into old age. However, age per se remains a significant predictor of vertical jump performance, further demonstrating deteriorated muscle quality at old age (sarcosthenia).

Sarc-F and muscle function in community dwelling adults with aged care service needs: baseline and post-training relationship

Background

This study sought to better understand the psychometric properties of the SARC-F, by examining the baseline and training-related relationships between the five SARC-F items and objective measures of muscle function. Each of the five items of the SARC-F are scored from 0 to 2, with total score of four or more indicative of likely sarcopenia.

Methods

This manuscript describes a sub-study of a larger step-wedge, randomised controlled 24-week progressive resistance and balance training (PRBT) program trial for Australian community dwelling older adults accessing government supported aged care. Muscle function was assessed using handgrip strength, isometric knee extension, 5-time repeated chair stand and walking speed over 4 m. Associations within and between SARC-F categories and muscle function were assessed using multiple correspondence analysis (MCA) and multinomial regression, respectively.

Results

Significant associations were identified at baseline between SARC-F total score and measures of lower-body muscle function (r =  - 0.62 to 0.57; p ≤ 0.002) in 245 older adults. MCA analysis indicated the first three dimensions of the SARC-F data explained 48.5% of the cumulative variance. The initial dimension represented overall sarcopenia diagnosis, Dimension 2 the ability to displace the body vertically, and Dimension 3 walking ability and falls status. The majority of the 168 older adults who completed the PRBT program reported no change in their SARC-F diagnosis or individual item scores (56.5-79.2%). However, significant associations were obtained between training-related changes in SARC-F total and item scores and changes in walking speed and chair stand test performance (r =  - 0.30 to 0.33; p < 0.001 and relative risk ratio = 0.40-2.24; p < 0.05, respectively). MCA analysis of the change score data indicated that the first two dimensions explained 32.2% of the cumulative variance, with these dimensions representing whether a change occurred and the direction of change, respectively.

Discussion

The results advance our comprehension of the psychometric properties on the SARC-F, particularly its potential use in assessing changes in muscle function. Older adults' perception of their baseline and training-related changes in their function, as self-reported by the SARC-F, closely matched objectively measured muscle function tests. This is important as there may be a lack of concordance between self-reported and clinician-measured assessments of older adults' muscle function. However, the SARC-F has a relative lack of sensitivity to detecting training-related changes, even over a period of 24 weeks.

Conclusions

Results of this study may provide clinicians and researchers a greater understanding of how they may use the SARC-F and its potential limitations. Future studies may wish to further examine the SARC-F's sensitivity of change, perhaps by adding a few additional items or an additional category of performance to each item.

Osteoporosis and Sarcopenia Increase Frailty Syndrome in the Elderly

Musculoskeletal aging is a major public health interesting and strain due to the significant demographic modifications in the population, and it is linked to high risk of falls, loss of autonomy in elderly individuals and institutionalization with small health outcomes. Thus, this pathological status is related to high morbidity and health care rates. Bone mass and muscle mass and strength increase during late adolescence and early adulthood but start to reduce noticeably from the fifth decade of life and are closely linked. Bone and muscle tissues were increasingly recognized, as endocrine target organs and endocrine organs themselves, interacting through paracrine and endocrine signals. During growth, bone mineral content closely correlates with muscle mass, and several evidences suggest that osteoporosis and sarcopenia present common pathophysiological factors and show the correlation between low bone mineral density and sarcopenia in both men and women. Then, sarcopenia and osteoporosis, typical features of aging, are often associated with each other and with the frailty syndrome. In particular, sarcopenia and osteoporosis are major contributors to disability and frailty and the common denominators are age-related chronic inflammation, changes in body composition and hormonal imbalance. Frailty syndrome is characterized by a reduced response to stress, triggering the decline of the physiological functioning of the various systems. Frailty syndrome, typical of the older people, is frequently associated with a reduction in the quality of life and mobility. Falls often are the basis of reduced mobility and ability to perform the common functions of daily life and the increase in the number of institutionalizations. Moreover, the reduction of muscle mass, associated with altered muscle composition, fat and fibrous infiltration and alterations in innervations, and the increase in fat mass, have a synergistic effect on the increase in cardiovascular risk. The aim of this review is to analyze the pathophysiological mechanisms underlying the frailty syndrome and its association with sarcopenia and osteoporosis, and investigate possible intervention measures.

Physical exercise in aging human skeletal muscle increases mitochondrial calcium uniporter expression levels and affects mitochondria dynamics

Age‐related sarcopenia is characterized by a progressive loss of muscle mass with decline in specific force, having dramatic consequences on mobility and quality of life in seniors. The etiology of sarcopenia is multifactorial and underlying mechanisms are currently not fully elucidated. Physical exercise is known to have beneficial effects on muscle trophism and force production. Alterations of mitochondrial Ca²⁺ homeostasis regulated by mitochondrial calcium uniporter (MCU) have been recently shown to affect muscle trophism in vivo in mice. To understand the relevance of MCU‐dependent mitochondrial Ca²⁺ uptake in aging and to investigate the effect of physical exercise on MCU expression and mitochondria dynamics, we analyzed skeletal muscle biopsies from 70‐year‐old subjects 9 weeks trained with either neuromuscular electrical stimulation (ES) or leg press. Here, we demonstrate that improved muscle function and structure induced by both trainings are linked to increased protein levels of MCU. Ultrastructural analyses by electron microscopy showed remodeling of mitochondrial apparatus in ES‐trained muscles that is consistent with an adaptation to physical exercise, a response likely mediated by an increased expression of mitochondrial fusion protein OPA1. Altogether these results indicate that the ES‐dependent physiological effects on skeletal muscle size and force are associated with changes in mitochondrial‐related proteins involved in Ca²⁺ homeostasis and mitochondrial shape. These original findings in aging human skeletal muscle confirm the data obtained in mice and propose MCU and mitochondria‐related proteins as potential pharmacological targets to counteract age‐related muscle loss.

Frailty and sarcopenia in Bogotá: results from the SABE Bogotá Study

BACKGROUND

Latin American countries like Colombia are experiencing a unique aging process due to a mixed epidemiological regime of communicable and non-communicable diseases.

AIMS

To estimate the prevalence of frailty and sarcopenia among older adults in Colombia and identify variables associated with these conditions.

METHODS

Data come from the "Salud Bienestar y Envejecimiento" (SABE) Bogotá Study, a cross-sectional study conducted in 2012 in Bogotá, Colombia. Sociodemographic, health, cognitive and anthropometric measures were collected from 2000 community-dwelling adults aged 60 years and older. Frailty variable was created using the Fried phenotype and sarcopenia following the European Working Group on Sarcopenia in Older People algorithm. Logistic regression analyses were used to identify factors associated with frailty and sarcopenia.

RESULTS

A total of 135 older adults are frail (9.4 %), while 166 have sarcopenia (11.5 %). Older age and female gender have a significant association with both conditions (Frailty: Age OR 1.05, 95 % CI 1.03-1.06, Gender OR 1.44, 95 % CI 1.12-1.84; Sarcopenia: Age 1.04, 95 % CI 1.02-1.07, Gender OR 1.51, 95 % CI 1.05-2.17). Depression was also significantly associated with frailty (OR 1.17, 95 % CI 1.12-1.22), while smoking was significantly associated with sarcopenia (OR 2.38, 95 % CI 1.29-4.37). Finally, higher function, measured by independence in IADL (Instrumental Activities of Daily Living) was significantly associated with less frailty (OR 0.74, 95 % CI 0.64-0.86). Education, higher number of comorbidities, better MMSE score, activities of daily living disability and alcohol consumption were not significantly associated with frailty or sarcopenia.

CONCLUSIONS

Frailty, sarcopenia and multimorbidity are overlapping, yet distinct conditions in this sample. There are potentially reversible factors that are associated with frailty and sarcopenia in this sample. Future studies need to analyze the best way to prevent these conditions, and examine individuals that have frailty, sarcopenia and comorbidities to design interventions to improve their quality of life.

Counteracting Age-related Loss of Skeletal Muscle Mass: a clinical and ethnological trial on the role of protein supplementation and training load (CALM Intervention Study): study protocol for a randomized controlled trial

Background

Aging is associated with decreased muscle mass and functional capacity, which in turn decrease quality of life. The number of citizens over the age of 65 years in the Western world will increase by 50 % over the next four decades, and this demographic shift brings forth new challenges at both societal and individual levels. Only a few longitudinal studies have been reported, but whey protein supplementation seems to improve muscle mass and function, and its combination with heavy strength training appears even more effective. However, heavy resistance training may reduce adherence to training, thereby attenuating the overall benefits of training. We hypothesize that light load resistance training is more efficient when both adherence and physical improvement are considered longitudinally. We launched the interdisciplinary project on Counteracting Age-related Loss of Skeletal Muscle Mass (CALM) to investigate the impact of lifestyle changes on physical and functional outcomes as well as everyday practices and habits in a qualitative context.

Methods

We will randomize 205 participants older than 65 years to be given 1 year of two daily nutrient supplements with 10 g of sucrose and 20 g of either collagen protein, carbohydrates, or whey. Further, two groups will perform either heavy progressive resistance training or light load training on top of the whey supplement.

Discussion

The primary outcome of the CALM Intervention Study is the change in thigh cross-sectional area. Moreover, we will evaluate changes in physical performance, muscle fiber type and acute anabolic response to whey protein ingestion, sensory adaptation, gut microbiome, and a range of other measures, combined with questionnaires on life quality and qualitative interviews with selected subjects. The CALM Intervention Study will generate scientific evidence and recommendations to counteract age-related loss of skeletal muscle mass in elderly individuals.

Trial registration

ClinicalTrials.gov NCT02034760. Registered on 10 January 2014.

ClinicalTrials.gov NCT02115698. Registered on 14 April 2014.

Danish regional committee of the Capital Region H-4-2013-070. Registered on 4 July 2013.

Danish Data Protection Agency 2012-58-0004 – BBH-2015-001 I-Suite 03432. Registered on 9 January 2015.

Protein Requirements and Recommendations for Older People: A Review

Declines in skeletal muscle mass and strength are major contributors to increased mortality, morbidity and reduced quality of life in older people. Recommended Dietary Allowances/Intakes have failed to adequately consider the protein requirements of the elderly with respect to function. The aim of this paper was to review definitions of optimal protein status and the evidence base for optimal dietary protein. Current recommended protein intakes for older people do not account for the compensatory loss of muscle mass that occurs on lower protein intakes. Older people have lower rates of protein synthesis and whole-body proteolysis in response to an anabolic stimulus (food or resistance exercise). Recommendations for the level of adequate dietary intake of protein for older people should be informed by evidence derived from functional outcomes. Randomized controlled trials report a clear benefit of increased dietary protein on lean mass gain and leg strength, particularly when combined with resistance exercise. There is good consistent evidence (level III-2 to IV) that consumption of 1.0 to 1.3 g/kg/day dietary protein combined with twice-weekly progressive resistance exercise reduces age-related muscle mass loss. Older people appear to require 1.0 to 1.3 g/kg/day dietary protein to optimize physical function, particularly whilst undertaking resistance exercise recommendations.

Sarcopenia and Osteoporosis

Public health strategies designed to accomodate the ever-increasing human lifespan are urgently required. A good clinical understanding of frailty, as well as knowledge regarding how to prevent it, will therefore be required in order to overcome this challenge. Sarcopenia is an important component of the frailty syndrome, and its association with osteoporosis can lead to fractures and incident disability. Therefore, this review examined the literatuire pertaining to the association of sarcopenia with osteoporosis in order to assess preventive strategies.

Electrical stimulation counteracts muscle decline in seniors

The loss in muscle mass coupled with a decrease in specific force and shift in fiber composition are hallmarks of aging. Training and regular exercise attenuate the signs of sarcopenia. However, pathologic conditions limit the ability to perform physical exercise. We addressed whether electrical stimulation (ES) is an alternative intervention to improve muscle recovery and defined the molecular mechanism associated with improvement in muscle structure and function. We analyzed, at functional, structural, and molecular level, the effects of ES training on healthy seniors with normal life style, without routine sport activity. ES was able to improve muscle torque and functional performances of seniors and increased the size of fast muscle fibers. At molecular level, ES induced up-regulation of IGF-1 and modulation of MuRF-1, a muscle-specific atrophy-related gene. ES also induced up-regulation of relevant markers of differentiating satellite cells and of extracellular matrix remodeling, which might guarantee shape and mechanical forces of trained skeletal muscle as well as maintenance of satellite cell function, reducing fibrosis. Our data provide evidence that ES is a safe method to counteract muscle decline associated with aging.