The adaptive response of skeletal muscle: What is the evidence?

Salmons, Stanley

doi:10.1002/mus.25949

Cited by 11 publications

(8 citation statements)

References 111 publications

(215 reference statements)

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“…The adult skeletal muscle is capable of adapting its properties in response to changing functional demands (SALMONS, 2017). The diversity of fibers provides the muscle an adaptation capacity in its myofibrillar system to continuously adjust to functional needs.…”

Section: Discussionmentioning

confidence: 99%

Effects of long-term physical exercise in the skeletal muscles of rats

Adala

Campos

2017

J Morphol Sci

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Introdcution: The effects of long-term physical exercise in the skeletal muscles were evaluated. Methods: 30 male Wistar rats, 25 days old each, were divided in 2 groups: trained (TG, n=21) and sedentary (SG, n=9). The TG group was subdivided in 3 groups: TGI, TGII and TGIII, n=7 in each group, and the SG was also subdivided in 3 groups: SGI, SGII and SGIII, n=3. The animals of the TG (I, II and III) performed running exercise on a electric running machine for 3, 6 and 9 weeks respectively. The animals of the sedentary groups remained without any exercise. After the experimental period the soleus (SOL), the extensor digitorum longus (EDL) and the plantaris (PL) muscles were extracted, weighed and analyzed by the histochemichal technique of mATPase to observe possible changes. Results: The TGIII showed a significant increase in the absolute values of muscle weight when compared to the TGI and TGII. There was an increase in the distribution of type I fibers and a decrease in types IIC and IIA in the SOL muscle. The EDL muscle showed an increase in IIA fibers and a decrease in IID IIB types. As for the PL muscle there was an increase in types IIA and IIAD and a decrease in IID type fibers. Conclusion: Physical exercise causes changes in the distribution of fiber types in the skeletal muscles of rats and confirms the capacity of the fibers to adapt to the requirements of the proposed physical exercise in order to achieve a better performance.

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Section: Discussionmentioning

confidence: 99%

Effects of long-term physical exercise in the skeletal muscles of rats

Adala

Campos

2017

J Morphol Sci

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“…In the lower extremity muscles examined (vastus lateralis), a stimulation period of approximately one year was indicated [19] . A literature search revealed that there were no study data available for the upper extremities in humans, but animal studies demonstrated that the effect achieved by direct muscle stimulation was not muscle specific regardless of their localization, function and fiber type composition [3] . That observation may imply the usefulness of ES also to any denervated human muscle.…”

Section: Discussionmentioning

confidence: 99%

“…Following a LMN lesion, structural and functional transformations of muscle properties occur different from those observed after an upper motor neuron (UMN) lesion. Denervation atrophy implies a decrease in muscle fiber diameters and a partial transformation into connective and adipose tissue in the muscle affected [3] . Interestingly, Helgason and coworkers found that electrical stimulation (ES) could restore contractile properties in structurally altered muscles of the lower extremities [4] .…”

Section: Introductionmentioning

confidence: 99%

Electrical stimulation alters muscle morphological properties in denervated upper limb muscles

Bersch

Fridén

2021

eBioMedicine

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Background Damage to lower motor neuron causes denervation and degeneration of the muscles affected. Experimental and clinical studies of muscle denervation in lower extremities demonstrated that direct electrical stimulation (ES) of muscle can prevent denervation atrophy and restore contractility. The aim of this study was to identify possible myogenic effect of ES on denervated forearm and hand muscles in persons with spinal cord injury (SCI) and tetraplegia. Methods This prospective interventional study with repeated measurement design included 22 patients aged 48·6 (± 15·7), 0·25 (0·1/46) years after spinal cord lesion, AIS A-D. In each patient, two electrophysiologically-confirmed denervated muscles in the hand and forearm were analyzed – one extrinsic (Extensor Carpi Ulnaris - ECU) and one intrinsic (1st Dorsal Interosseus - IOD1). Muscles were stimulated for 33 min, five times per week over a 12-weeks period. Using ultrasonography (USG), muscle thickness (MT) and pennation angle (PA) of these muscles were determined at start and end of the stimulation period. Findings MT of IOD1 increased from 6·3 mm (± 3·2 mm) to 9·2 mm (± 2·4 mm) ( p = 0·004) and the PA from 5·5° (± 3·0°) to 11° (± 2·2°) ( p = 0·001). The corresponding values for the ECU were 5·5 mm (± 2·5 mm) to 7·0 mm (± 2·2 mm) ( p = 0·039) and 5·5° (± 3·4°) to 9·4° (± 3·8°) ( p = 0·005), respectively. The correlation of MT between baseline and completion was r = 0·58 ( p = 0·037) for the ECU and r = 0·63 ( p = 0·008) for the IOD1. Interpretation 12 weeks of direct muscle stimulation increases the MT and PA of the denervated intrinsic and extrinsic hand muscles studied. Funding Swiss Paraplegic Centre, Switzerland

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“…The individual skeletal muscle fibers possess a remarkable ability to adapt to altered physical demands and can adjust both the overall size, metabolic‐ and vascular apparatus and capacity to meet the new functional requisites 7 . The question of whether muscle fiber types can change phenotype from one type to another as a result of changes in muscle activity has been studied experimentally since the start of the 1960s and 1970s in animal models 8 and humans, 9 respectively. In humans, the type 2A and type 2X muscle fibers seem to readily interconvert in response to changes in physical activity patterns, in that increased physical activity increases the relative number of type 2A muscle fibers on the expense of the relative number of type 2X muscle fibers, 10‐12 and vice versa by reduced activity patterns 11,12 .…”

Section: Introductionmentioning

confidence: 99%

Human skeletal muscle fiber type percentage and area after reduced muscle use: A systematic review and meta‐analysis

Vikne¹,

Strøm

Pripp

et al. 2020

Scandinavian Med Sci Sports

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The main objective of this systematic review was to examine the effect of reduced muscle activity on the relative number of type 1 muscle fibers (%) in the human vastus lateralis muscle. Other objectives were changes in type 2A and 2X percentages and muscle fiber cross‐sectional area. We conducted systematic literature searches in eight databases and included studies assessing type 1 fiber percentage visualized by ATPase or immunohistochemical staining before and after a period (≥14 days) of reduced muscle activity. The reduced muscle activity models were detraining, leg unloading, and bed rest. Forty‐two studies comprising 451 participants were included. Effect sizes were calculated as the mean difference between baseline and follow‐up and Generic Inverse Variance tests with random‐effects models were used for the weighted summary effect size. Overall, the mean type 1 muscle fiber percentage was significantly reduced after interventions (−1.94%‐points, 95% CI [−3.37, −0.51], P = .008), with no significant differences between intervention models (P = .86). Meta‐regression showed no effect of study duration on type 1 fiber percentage (P = .98). Conversely, the overall type 2X fiber percentage increased after reduced muscle activity (P < .001). The CSA of the muscle fiber types decreased after the study period (all P‐values < 0.001) with greater reductions in type 2 than type 1 fibers (P < .001). The result of this meta‐analysis display that the type 1 muscle fiber percentage decrease as a result of reduced muscle activity, although the effect size is relatively small.

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The adaptive response of skeletal muscle: What is the evidence?

Cited by 11 publications

References 111 publications

Effects of long-term physical exercise in the skeletal muscles of rats

Effects of long-term physical exercise in the skeletal muscles of rats

Electrical stimulation alters muscle morphological properties in denervated upper limb muscles

Human skeletal muscle fiber type percentage and area after reduced muscle use: A systematic review and meta‐analysis

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