The decline in skeletal muscle mass with aging is mainly attributed to a reduction in type II muscle fiber size

Nilwik, Rachél; Snijders, Tim; Leenders, Marika; Groen, Bart B. L.; Kranenburg, Janneau van; Verdijk, Lex B.; Loon, Luc J. C. van

doi:10.1016/j.exger.2013.02.012

Cited by 583 publications

(505 citation statements)

References 50 publications

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“…Also, human myofiber loss has not unequivocally been reported. Recently, in m. vastus lateralis of healthy 70-year-old subjects, a decrease in muscle mass was solely explained by a decrease in type II fiber CSA, and not by a loss of myofibers (Nilwik et al 2013). Overall, it appears that in 25-month-old male C57BL/6J mice myofiber number size are well maintained.…”

Section: Effects Of Aging On Atrophy and Loss In Myofiber Numbermentioning

confidence: 74%

Plantaris muscle weakness in old mice: relative contributions of changes in specific force, muscle mass, myofiber cross-sectional area, and number

Ballak

Degens

Busé-Pot

et al. 2014

AGE

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The age-related decline in muscle function contributes to the movement limitations in daily life in old age. The age-related loss in muscle force is attributable to loss of myofibers, myofiber atrophy, and a reduction in specific force. The contribution of each of these determinants to muscle weakness in old age is, however, largely unknown. The objective of this study is to determine whether a loss in myofiber number, myofiber atrophy, and a reduction in specific muscle force contribute to the age-related loss of muscle force in 25-month-old mouse. Maximal isometric force of in situ m. plantaris of C57BL/6J male adult (9 months) and old (25 months) mice was determined and related to myofiber number, myofiber size, intramuscular connective tissue content, and proportion of denervated myofibers. Isometric maximal plantaris muscle force was 13 % lower in old than adult mice (0.97±0.05 N vs. 0.84±0.03 N; P<0.05). M. plantaris mass of old mice was not significantly smaller than that of adult mice. There was also no significant myofiber atrophy or myofiber loss. Specific muscle force of old mice was 25 % lower than that of adult mice (0.55±0.05 vs. 0.41± 0.03 N·mm −2 , P<0.01). In addition, with age, the proportion of type IIB myofibers decreased (43.6 vs. 38.4 %, respectively), while the connective tissue content increased (11.6 vs. 16.4 %, respectively). The agerelated reduction in maximal isometric plantaris muscle force in 25-month-old male C57BL/6J mice is mainly attributable to a reduction in specific force, which is for 5 % explicable by an age-related increase in connective tissue, rather than myofiber atrophy and myofiber loss.

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Section: Effects Of Aging On Atrophy and Loss In Myofiber Numbermentioning

confidence: 74%

Plantaris muscle weakness in old mice: relative contributions of changes in specific force, muscle mass, myofiber cross-sectional area, and number

Ballak

Degens

Busé-Pot

et al. 2014

AGE

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“…Ageing skeletal muscle undergoes chronic denervation, and the NMJ, the key structure that connects motor neuron nerves with muscle cells, shows increased deterioration in structure and function with ageing 26, 27. Previous studies have shown that with ageing, type II fast‐twitch skeletal muscle fibres atrophy more than type I slow‐twitch fibres across multiple species 28, 29, 30. In addition, with ageing, NMJs are more vulnerable in fast‐twitch skeletal muscle fibres than in slow‐twitch skeletal muscle,31, 32, 33 but it is unclear why.…”

Section: Discussionmentioning

confidence: 99%

Cardiac troponin T and fast skeletal muscle denervation in ageing

Feng

Dong

et al. 2017

J cachexia sarcopenia muscle

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BackgroundAgeing skeletal muscle undergoes chronic denervation, and the neuromuscular junction (NMJ), the key structure that connects motor neuron nerves with muscle cells, shows increased defects with ageing. Previous studies in various species have shown that with ageing, type II fast‐twitch skeletal muscle fibres show more atrophy and NMJ deterioration than type I slow‐twitch fibres. However, how this process is regulated is largely unknown. A better understanding of the mechanisms regulating skeletal muscle fibre‐type specific denervation at the NMJ could be critical to identifying novel treatments for sarcopenia. Cardiac troponin T (cTnT), the heart muscle‐specific isoform of TnT, is a key component of the mechanisms of muscle contraction. It is expressed in skeletal muscle during early development, after acute sciatic nerve denervation, in various neuromuscular diseases and possibly in ageing muscle. Yet the subcellular localization and function of cTnT in skeletal muscle is largely unknown.MethodsStudies were carried out on isolated skeletal muscles from mice, vervet monkeys, and humans. Immunoblotting, immunoprecipitation, and mass spectrometry were used to analyse protein expression, real‐time reverse transcription polymerase chain reaction was used to measure gene expression, immunofluorescence staining was performed for subcellular distribution assay of proteins, and electromyographic recording was used to analyse neurotransmission at the NMJ.ResultsLevels of cTnT expression in skeletal muscle increased with ageing in mice. In addition, cTnT was highly enriched at the NMJ region—but mainly in the fast‐twitch, not the slow‐twitch, muscle of old mice. We further found that the protein kinase A (PKA) RIα subunit was largely removed from, while PKA RIIα and RIIβ are enriched at, the NMJ—again, preferentially in fast‐twitch but not slow‐twitch muscle in old mice. Knocking down cTnT in fast skeletal muscle of old mice: (i) increased PKA RIα and reduced PKA RIIα at the NMJ; (ii) decreased the levels of gene expression of muscle denervation markers; and (iii) enhanced neurotransmission efficiency at NMJ.ConclusionsCardiac troponin T at the NMJ region contributes to NMJ functional decline with ageing mainly in the fast‐twitch skeletal muscle through interfering with PKA signalling. This knowledge could inform useful targets for prevention and therapy of age‐related decline in muscle function.

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“…Atrophy of type II muscle fibers without any reduction in the number of muscle cells is also found in Nilwik's study. [13][14][15] A previous study also found the presence of increased LELM after performign the muscle strengthening exercises. These differences are attributed to the fact that the all participants are women in the age range of 46-56 years in this study while the research done by Thomas consists of 30-40 years old male sand females.…”

Section: Discussionmentioning

confidence: 99%

Effects of Quadriceps Strengthening Exercise on Quadriceps Muscle Strength and Its Relation to Lower Extremity Lean Mass

Desiana¹,

Moeliono²,

Prabowo³

2017

IJIHS

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Objective: To discover whether quadriceps resistance exercise could increase quadriceps strength as well as its relation to lower extremity lean mass. Methods:This study was a pre-and post-experimental study in which 36 participants with knee OA grade 2 and 3 were recruited. Assesment of leg lean mass and quadriceps strength was taken before and after intervention. Participants practiced quadriceps isotonic resistance exercise 3 times a week for 8 weeks. This study was conducted in Dr. Hasan Sadikin General Hospital, Bandung from September 2014 to February 2015.Results: After the intervention, an increase in quadriceps strength was seen but not in the lower extremity lean mass. Statistical analysis showed that there was no correlation between lower extremity lean mass and quadriceps strength. Conclusions:Quadriceps strength is found to increase after intervention. No increase is found in the lower extremity lean mass.

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The decline in skeletal muscle mass with aging is mainly attributed to a reduction in type II muscle fiber size

Cited by 583 publications

References 50 publications

Plantaris muscle weakness in old mice: relative contributions of changes in specific force, muscle mass, myofiber cross-sectional area, and number

Plantaris muscle weakness in old mice: relative contributions of changes in specific force, muscle mass, myofiber cross-sectional area, and number

Cardiac troponin T and fast skeletal muscle denervation in ageing

Effects of Quadriceps Strengthening Exercise on Quadriceps Muscle Strength and Its Relation to Lower Extremity Lean Mass

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