scholarly journals Age-Related Skeletal Muscle Dysfunction Is Aggravated by Obesity: An Investigation of Contractile Function, Implications and Treatment

Biomolecules ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 372
Author(s):  
Jason Tallis ◽  
Sharn Shelley ◽  
Hans Degens ◽  
Cameron Hill
Keyword(s):  
Skeletal Muscle ◽  
Muscle Function ◽  
Functional Performance ◽  
Contractile Function ◽  
Adult Population ◽  
Poor Quality ◽  
Whole Body ◽  
Skeletal Muscle Function ◽  
Global Epidemic ◽  
Age Related

Obesity is a global epidemic and coupled with the unprecedented growth of the world’s older adult population, a growing number of individuals are both old and obese. Whilst both ageing and obesity are associated with an increased prevalence of chronic health conditions and a substantial economic burden, evidence suggests that the coincident effects exacerbate negative health outcomes. A significant contributor to such detrimental effects may be the reduction in the contractile performance of skeletal muscle, given that poor muscle function is related to chronic disease, poor quality of life and all-cause mortality. Whilst the effects of ageing and obesity independently on skeletal muscle function have been investigated, the combined effects are yet to be thoroughly explored. Given the importance of skeletal muscle to whole-body health and physical function, the present study sought to provide a review of the literature to: (1) summarise the effect of obesity on the age-induced reduction in skeletal muscle contractile function; (2) understand whether obesity effects on skeletal muscle are similar in young and old muscle; (3) consider the consequences of these changes to whole-body functional performance; (4) outline important future work along with the potential for targeted intervention strategies to mitigate potential detrimental effects.

scholarly journals Gait disturbances and muscle dysfunction in fibroblast growth factor 2 knockout mice

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
C. Homer-Bouthiette ◽  
L. Xiao ◽  
Marja M. Hurley
Keyword(s):  
Skeletal Muscle ◽  
Growth Factor ◽  
Muscle Strength ◽  
Fibroblast Growth Factor ◽  
Muscle Function ◽  
Fibroblast Growth Factor 2 ◽  
Fibroblast Growth ◽  
Skeletal Muscle Function ◽  
Age Related ◽  
Gait Disturbances

AbstractFibroblast growth factor 2 (FGF2) is important in musculoskeletal homeostasis, therefore the impact of reduction or Fgf2 knockout on skeletal muscle function and phenotype was determined. Gait analysis as well as muscle strength testing in young and old WT and Fgf2KO demonstrated age-related gait disturbances and reduction in muscle strength that were exacerbated in the KO condition. Fgf2 mRNA and protein were significantly decreased in skeletal muscle of old WT compared with young WT. Muscle fiber cross-sectional area was significantly reduced with increased fibrosis and inflammatory infiltrates in old WT and Fgf2KO vs. young WT. Inflammatory cells were further significantly increased in old Fgf2KO compared with old WT. Lipid-related genes and intramuscular fat was increased in old WT and old Fgf2KO with a further increase in fibro-adipocytes in old Fgf2KO compared with old WT. Impaired FGF signaling including Increased β-Klotho, Fgf21 mRNA, FGF21 protein, phosphorylated FGF receptors 1 and 3, was observed in old WT and old Fgf2KO. MAPK/ ERK1/2 was significantly increased in young and old Fgf2KO. We conclude that Fgf2KO, age-related decreased FGF2 in WT mice, and increased FGF21 in the setting of impaired Fgf2 expression likely contribute to impaired skeletal muscle function and sarcopenia in mice.

The Effects of Aging and Training on Skeletal Muscle

1998 ◽  
Vol 26 (4) ◽  
pp. 598-602 ◽  
Author(s):  
Donald T. Kirkendall ◽  
William E. Garrett
Keyword(s):  
Skeletal Muscle ◽  
Muscle Mass ◽  
Muscle Function ◽  
Cellular Level ◽  
Type I ◽  
Loss Of Function ◽  
Skeletal Muscle Function ◽  
Cross Sectional ◽  
Age Related ◽  
General Slowing

Aging results in a gradual loss of muscle function, and there are predictable age-related alterations in skeletal muscle function. The typical adult will lose muscle mass with age; the loss varies according to sex and the level of muscle activity. At the cellular level, muscles loose both cross-sectional area and fiber numbers, with type II muscle fibers being the most affected by aging. Some denervation of fibers may occur. The combination of these factors leads to an increased percentage of type I fibers in older adults. Metabolically, the glycolytic enzymes seem to be little affected by aging, but the aerobic enzymes appear to decline with age. Aged skeletal muscle produces less force and there is a general “slowing” of the mechanical characteristics of muscle. However, neither reduced muscle demand nor the subsequent loss of function is inevitable with aging. These losses can be minimized or even reversed with training. Endurance training can improve the aerobic capacity of muscle, and resistance training can improve central nervous system recruitment of muscle and increase muscle mass. Therefore, physical activity throughout life is encouraged to prevent much of the age-related impact on skeletal muscle.

scholarly journals Action of GH on skeletal muscle function: molecular and metabolic mechanisms

2013 ◽  
Vol 52 (1) ◽  
pp. R107-R123 ◽  
Author(s):  
Viral Chikani ◽  
Ken K Y Ho
Keyword(s):  
Skeletal Muscle ◽  
Muscle Function ◽  
The Elderly ◽  
Energy System ◽  
Muscle Performance ◽  
Whole Body ◽  
Target Tissue ◽  
Dependent Manner ◽  
Skeletal Muscle Function ◽  
Body Protein

Skeletal muscle is a target tissue of GH. Based on its anabolic properties, it is widely accepted that GH enhances muscle performance in sports and muscle function in the elderly. This paper critically reviews information on the effects of GH on muscle function covering structure, protein metabolism, the role of IGF1 mediation, bioenergetics and performance drawn from molecular, cellular and physiological studies on animals and humans. GH increases muscle strength by enhancing muscle mass without affecting contractile force or fibre composition type. GH stimulates whole-body protein accretion with protein synthesis occurring in muscular and extra-muscular sites. The energy required to power muscle function is derived from a continuum of anaerobic and aerobic sources. Molecular and functional studies provide evidence that GH stimulates the anaerobic and suppresses the aerobic energy system, in turn affecting power-based functional measures in a time-dependent manner. GH exerts complex multi-system effects on skeletal muscle function in part mediated by the IGF system.

scholarly journals Skeletal muscle function during the progression of cancer cachexia in the male ApcMin/+ mouse

2018 ◽  
Vol 124 (3) ◽  
pp. 684-695 ◽  
Author(s):  
Brandon N. VanderVeen ◽  
Justin P. Hardee ◽  
Dennis K. Fix ◽  
James A. Carson
Keyword(s):  
Skeletal Muscle ◽  
Mrna Expression ◽  
Muscle Function ◽  
Cancer Cachexia ◽  
Whole Body ◽  
Functional Improvement ◽  
Cytokine Signaling ◽  
Inflammatory Signaling ◽  
Skeletal Muscle Function ◽  
Tetanic Force

While cancer-induced skeletal muscle wasting has been widely investigated, the drivers of cancer-induced muscle functional decrements are only beginning to be understood. Decreased muscle function impacts cancer patient quality of life and health status, and several potential therapeutics have failed in clinical trials due to a lack of functional improvement. Furthermore, systemic inflammation and intrinsic inflammatory signaling’s role in the cachectic disruption of muscle function requires further investigation. We examined skeletal muscle functional properties during cancer cachexia and determined their relationship to systemic and intrinsic cachexia indices. Male ApcMin/+ (MIN) mice were stratified by percent body weight loss into weight stable (WS; <5% loss) or cachectic (CX; >5% loss). Age-matched C57BL/6 littermates served as controls. Tibialis anterior (TA) twitch properties, tetanic force, and fatigability were examined in situ. TA protein and mRNA expression were examined in the nonstimulated leg. CX decreased muscle mass, tetanic force (Po), and specific tetanic force (sPo). Whole body and muscle fatigability were increased in WS and CX. CX had slower contraction rates, +dP/d t and −dP/d t, which were inversely associated with muscle signal transducer and activator of transcription 3 ( STAT3) and p65 activation. STAT3 and p65 activation were also inversely associated with Po. However, STAT3 was not related to sPo or fatigue. Muscle suppressor of cytokine signaling 3 mRNA expression was negatively associated with TA weight, Po, and sPo but not fatigue. Our study demonstrates that multiple functional deficits that occur with cancer cachexia are associated with increased muscle inflammatory signaling. Notably, muscle fatigability is increased in the MIN mouse before cachexia development. NEW & NOTEWORTHY Recent studies have identified decrements in skeletal muscle function during cachexia. We have extended these studies by directly relating decrements in muscle function to established cachexia indices. Our results demonstrate that a slow-fatigable contractile phenotype is developed during the progression of cachexia that coincides with increased muscle inflammatory signaling. Furthermore, regression analysis identified predictors of cancer-induced muscle dysfunction. Last, we report the novel finding that whole body and muscle fatigability were increased before cachexia development.

Disruption of muscle renin-angiotensin system in AT1a−/−mice enhances muscle function despite reducing muscle mass but compromises repair after injury

2012 ◽  
Vol 303 (3) ◽  
pp. R321-R331 ◽  
Author(s):  
Kate T. Murphy ◽  
Andrew M. Allen ◽  
Annabel Chee ◽  
Timur Naim ◽  
Gordon S. Lynch
Keyword(s):  
Skeletal Muscle ◽  
Muscle Mass ◽  
Muscle Function ◽  
Renin Angiotensin System ◽  
Whole Body ◽  
Ras Signaling ◽  
Skeletal Muscle Function ◽  
Angiotensin System ◽  
Renin Angiotensin

The role of the renin-angiotensin system (RAS) in vasoregulation is well established, but a localized RAS exists in multiple tissues and exerts diverse functions including autonomic control and thermogenesis. The role of the RAS in the maintenance and function of skeletal muscle is not well understood, especially the role of angiotensin peptides, which appear to contribute to muscle atrophy. We tested the hypothesis that mice lacking the angiotensin type 1A receptor (AT1A−/−) would exhibit enhanced whole body and skeletal muscle function and improved regeneration after severe injury. Despite 18- to 20-wk-old AT1A−/−mice exhibiting reduced muscle mass compared with controls ( P < 0.05), the tibialis anterior (TA) muscles produced a 25% higher maximum specific (normalized) force ( P < 0.05). Average fiber cross-sectional area (CSA) and fiber oxidative capacity was not different between groups, but TA muscles from AT1A−/−mice had a reduced number of muscle fibers as well as a higher proportion of type IIx/b fibers and a lower proportion of type IIa fibers ( P < 0.05). Measures of whole body function (grip strength, rotarod performance, locomotor activity) were all improved in AT1A−/−mice ( P < 0.05). Surprisingly, the recovery of muscle mass and fiber CSA following myotoxic injury was impaired in AT1A−/−mice, in part by impaired myoblast fusion, prolonged collagen infiltration and inflammation, and delayed expression of myogenic regulatory factors. The findings support the therapeutic potential of RAS inhibition for enhancing whole body and skeletal muscle function, but they also reveal the importance of RAS signaling in the maintenance of muscle mass and for normal fiber repair after injury.

scholarly journals Age-related changes in isolated mouse skeletal muscle function are dependent on sex, muscle, and contractility mode

2020 ◽  
Vol 319 (3) ◽  
pp. R296-R314
Author(s):  
Cameron Hill ◽  
Rob S. James ◽  
Val. M. Cox ◽  
Frank Seebacher ◽  
Jason Tallis
Keyword(s):  
Skeletal Muscle ◽  
Muscle Mass ◽  
Fatigue Resistance ◽  
Muscle Function ◽  
Isometric Force ◽  
Muscle Quality ◽  
Skeletal Muscle Function ◽  
Cross Sectional ◽  
Mouse Skeletal Muscle ◽  
Age Related

The present study aimed to simultaneously examine the age-related, muscle-specific, sex-specific, and contractile mode-specific changes in isolated mouse skeletal muscle function and morphology across multiple ages. Measurements of mammalian muscle morphology, isometric force and stress (force/cross-sectional area), absolute and normalized (power/muscle mass) work-loop power across a range of contractile velocities, fatigue resistance, and myosin heavy chain (MHC) isoform concentration were measured in 232 isolated mouse (CD-1) soleus, extensor digitorum longus (EDL), and diaphragm from male and female animals aged 3, 10, 30, 52, and 78 wk. Aging resulted in increased body mass and increased soleus and EDL muscle mass, with atrophy only present for female EDL by 78 wk despite no change in MHC isoform concentration. Absolute force and power output increased up to 52 wk and to a higher level for males. A 23–36% loss of isometric stress exceeded the 14–27% loss of power normalized to muscle mass between 10 wk and 52 wk, although the loss of normalized power between 52 and 78 wk continued without further changes in stress ( P > 0.23). Males had lower power normalized to muscle mass than females by 78 wk, with the greatest decline observed for male soleus. Aging did not cause a shift toward slower contractile characteristics, with reduced fatigue resistance observed in male EDL and female diaphragm. Our findings show that the loss of muscle quality precedes the loss of absolute performance as CD-1 mice age, with the greatest effect seen in male soleus, and in most instances without muscle atrophy or an alteration in MHC isoforms.

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