-
International Journal of Molecular... Jun 2022Disuse muscle atrophy is identified as the physiological, biochemical, morphological, and functional changes during restricted movement, immobilization, or...
Disuse muscle atrophy is identified as the physiological, biochemical, morphological, and functional changes during restricted movement, immobilization, or weightlessness. Although its internal mechanism has been extensively studied in mammals and was thought to be mainly related to oxidative stress, it was unclear whether it behaved consistently in non-mammals such as chickens. In this study, we tried to construct a disuse atrophy model of the gastrocnemius muscle in chickens by limb immobilization, and collected the gastrocnemius muscles of the fixed group and the control group for RNA sequencing. Through analysis of muscle loss, HE staining, immunohistochemistry, and oxidative stress level, we found that limb immobilization could lead to loss of muscle mass, decrease in muscle fiber diameter, decrease in the proportion of slow muscle fibers, and increase in the proportion of fast muscle fibers, and also cause elevated levels of oxidative stress. In addition, a total of 565 different expression genes (DEGs) were obtained by RNA sequencing, which was significantly enriched in the biological processes such as cell proliferation and apoptosis, reactive oxygen species metabolism, and fast and slow muscle fiber transformation, and it showed that the FOXO signaling pathway, closely related to muscle atrophy, was activated. In brief, we initially confirmed that limb immobilization could induce disuse atrophy of skeletal muscle, and oxidative stress was involved in the process of disuse muscle atrophy.
Topics: Animals; Chickens; Mammals; Muscle Fibers, Skeletal; Muscle, Skeletal; Muscular Atrophy; Muscular Disorders, Atrophic
PubMed: 35805900
DOI: 10.3390/ijms23136892 -
Journal of Anatomy Oct 2021Children who idiopathically toe-walk (ITW) habitually operate at greater plantarflexion angles and thus, at shorter muscle-tendon unit (MTU) lengths than typically...
Children who idiopathically toe-walk (ITW) habitually operate at greater plantarflexion angles and thus, at shorter muscle-tendon unit (MTU) lengths than typically developing (TD) children. Therefore, it is often assumed that habitual use of the gastrocnemius muscle in this way will cause remodelling of the muscle-tendon architecture compared to TD children. However, the gastrocnemius muscle architecture of children who ITW has never been measured. It is essential that we gain a better understanding of these muscle-tendon properties, to ensure that appropriate clinical interventions can be provided for these children. Five children who ITW (age 8 ± 2 years) and 14 TD children (age 10 ± 2 years) participated in this study. Ultrasound was combined with isokinetic dynamometry and surface electromyography, to measure muscle architecture at common positions and passive lengthening properties of the gastrocnemius muscle and tendon across full range of motion. Regardless of which common condition groups were compared under, both the absolute and normalised to MTU muscle belly and fascicle lengths were always longer, and the Achilles tendon length was always shorter in children who ITW than TD children (p < 0.05; large effect sizes). The passive lengthening properties of the muscle and tendon were not different between groups (p > 0.05); however, passive joint stiffness was greater in children who ITW at maximum dorsiflexion (p = 0.001) and at a joint moment common to all participants (p = 0.029). Consequently, the findings of this pilot study indicate a remodelling of the relative MTU that does not support the concept that children who ITW commonly experience muscle shortening. Therefore, greater consideration of the muscle and tendon properties are required when prescribing clinical interventions that aim to lengthen the MTU, and treatments may be better targeted at the Achilles tendon in children who ITW.
Topics: Achilles Tendon; Ankle Joint; Cerebral Palsy; Child; Humans; Muscle, Skeletal; Pilot Projects; Range of Motion, Articular; Toes; Ultrasonography
PubMed: 34109625
DOI: 10.1111/joa.13464 -
Journal of Anatomy Jan 2022Assessment of regional muscle architecture is primarily done through the study of animals, human cadavers, or using b-mode ultrasound imaging. However, there remain...
Assessment of regional muscle architecture is primarily done through the study of animals, human cadavers, or using b-mode ultrasound imaging. However, there remain several limitations to how well such measurements represent in vivo human whole muscle architecture. In this study, we developed an approach using diffusion tensor imaging and magnetic resonance imaging to quantify muscle fibre lengths in different muscle regions along a muscle's length and width. We first tested the between-day reliability of regional measurements of fibre lengths in the medial (MG) and lateral gastrocnemius (LG) and found good reliability for these measurements (intraclass correlation coefficient [ICC] = 0.79 and ICC = 0.84, respectively). We then applied this approach to a group of 32 participants including males (n = 18), females (n = 14), young (24 ± 4 years) and older (70 ± 2 years) adults. We assessed the differences in regional muscle fibre lengths between different muscle regions and between individuals. Additionally, we compared regional muscle fibre lengths between sexes, age groups, and muscles. We found substantial variability in fibre lengths between different regions within the same muscle and between the MG and the LG across individuals. At the group level, we found no difference in mean muscle fibre length between males and females, nor between young and older adults, or between the MG and the LG. The high variability in muscle fibre lengths between different regions within the same muscle, possibly expands the functional versatility of the muscle for different task requirements. The high variability between individuals supports the use of subject-specific measurements of muscle fibre lengths when evaluating muscle function.
Topics: Animals; Diffusion Tensor Imaging; Female; Magnetic Resonance Imaging; Male; Muscle Fibers, Skeletal; Muscle, Skeletal; Reproducibility of Results
PubMed: 34411299
DOI: 10.1111/joa.13539 -
IEEE Transactions on Bio-medical... Dec 2022Regulating the impedance of our joints is essential for the effective control of posture and movement. The impedance of a joint is governed mainly by the mechanical...
OBJECTIVE
Regulating the impedance of our joints is essential for the effective control of posture and movement. The impedance of a joint is governed mainly by the mechanical properties of the muscle-tendon units spanning it. Many studies have quantified the net impedance of joints but not the specific contributions from the muscles and tendons. The inability to quantify both muscle and tendon impedance limits the ability to determine the causes underlying altered movement control associated with aging, neuromuscular injury, and other conditions that have different effects on muscle and tendon properties. Therefore, we developed a technique to quantify joint, muscle, and tendon impedance simultaneously and evaluated this technique at the human ankle.
METHODS
We used a single degree of freedom actuator to deliver pseudorandom rotations to the ankle while measuring the corresponding torques. We simultaneously measured the displacement of the medial gastrocnemius muscle-tendon junction with B-mode ultrasound. From these experimental measurements, we were able to estimate ankle, muscle, and tendon impedance using non-parametric system identification.
RESULTS
We validated our estimates by comparing them to previously reported measurements of muscle and tendon stiffness, the position-dependent component of impedance, to demonstrate that our technique generates reliable estimates of these properties.
CONCLUSION
Our approach can be used to clarify the respective contributions from the muscle and tendon to the net mechanics of a joint.
SIGNIFICANCE
This is a critical step forward in the ultimate goal of understanding how muscles and tendons govern ankle impedance during posture and movement.
Topics: Humans; Ankle; Electric Impedance; Ankle Joint; Tendons; Muscle, Skeletal; Biomechanical Phenomena
PubMed: 35594215
DOI: 10.1109/TBME.2022.3175646 -
PloS One 2022Immobilization of skeletal muscles causes muscle atrophy, muscle contracture, and muscle pain, the mechanisms of which are related to macrophage accumulation. However,...
PURPOSE
Immobilization of skeletal muscles causes muscle atrophy, muscle contracture, and muscle pain, the mechanisms of which are related to macrophage accumulation. However, muscle contractile exercise through a belt electrode device may mitigate macrophage accumulation. We hypothesized that such exercise would be effective in preventing myofiber atrophy, muscle contracture, and muscular pain. This study tested this hypothesis in immobilized rat gastrocnemius muscle.
MATERIALS AND METHODS
A total of 32 rats were divided into the following control and experimental groups: immobilization (immobilized treatment only), low-frequency (LF; immobilized treatment and muscle contractile exercise with a 2 s (do) /6 s (rest) duty cycle), and high-frequency (HF; immobilized treatment and muscle contractile exercise with a 2 s (do)/2 s (rest) duty cycle). Electrical stimulation was performed at 50 Hz and 4.7 mA, and muscle contractile exercise was applied to the lower limb muscles for 15 or 20 min/session (once daily) for 2 weeks (6 times/week). After the behavioral tests, the bilateral gastrocnemius muscles were collected for analysis.
RESULTS
The number of macrophages, the Atrogin-1 and MuRF-1 mRNA expression, and the hydroxyproline content in the HF group were lower than those in the immobilization and LF groups. The cross-sectional area (CSA) of type IIb myofibers in the superficial region, the PGC-1α mRNA expression, and the range of motion of dorsiflexion in the HF group were significantly higher than those in the immobilization and LF groups. The pressure pain thresholds in the LF and HF groups were significantly higher than that in the immobilization group, and the nerve growth factor (NGF) content in the LF and HF groups was significantly lower than that in the immobilization group.
CONCLUSION
Muscle contractile exercise through the belt electrode device may be effective in preventing immobilization-induced myofiber atrophy, muscle contracture, and muscular pain in the immobilized rat gastrocnemius muscle.
Topics: Animals; Contracture; Electrodes; Hydroxyproline; Immobilization; Muscle, Skeletal; Muscular Atrophy; Myalgia; Nerve Growth Factor; Physical Conditioning, Animal; RNA, Messenger; Rats
PubMed: 36149919
DOI: 10.1371/journal.pone.0275175 -
Journal of Orthopaedic Surgery and... Apr 2023The calcaneal tendon, the largest and strongest in the human body, is created by the common junction of tendons of the gastrocnemius and soleus muscles. It is not a... (Review)
Review
The calcaneal tendon, the largest and strongest in the human body, is created by the common junction of tendons of the gastrocnemius and soleus muscles. It is not a homogenous structure, being represented by layers in various arrangements. Morphological variability can be seen in the connection between the aponeurosis of the gastrocnemius muscle and the soleus muscle. Some types of plantaris tendon can be associated with a higher possibility of Achilles tendinopathy. Moreover, the presence of accessory structures, such as an accessory soleus muscle or additional gastrocnemius muscle heads may result in symptomatic pathologies. The main aim of this review is to summarize the current state of knowledge regarding the calcaneal tendon. Another aim is to present morphological variations of the calcaneal tendon and their clinical significance. Such information may be useful for clinicians, especially orthopedists, and surgeons. This review also provides an overview of embryological development and morphological variation among fetuses. Materials and methods: review was conducted according to PRISMA guidelines. An electronic search was conducted in five databases. Top quality tools were used to assess the quality of evidence in the studies reviewed. Research papers that made up the database of this review were analyzed, selected and assessed by two independently working researchers.
Topics: Humans; Achilles Tendon; Clinical Relevance; Tendinopathy; Muscle, Skeletal; Foot
PubMed: 37016428
DOI: 10.1186/s13018-023-03748-y -
International Journal of Environmental... Dec 2022Loss of functional movement capacity in older adults is related to adverse changes in musculotendinous morphology, but this relationship is poorly understood. This study...
Loss of functional movement capacity in older adults is related to adverse changes in musculotendinous morphology, but this relationship is poorly understood. This study examined the associations between musculotendinous morphology and functional movements, flexibility, and balance ability. Ninety-nine older women (66.6 ± 4.6 years, body mass index 23.5 ± 3.3 kg∙m−2) were recruited from Chonburi Province, Thailand. During one 90-min visit, muscle ultrasound imaging of vastus lateralis, biceps femoris, and medial gastrocnemius muscles, and tendon ultrasonography of the Achilles tendon and patellar tendon were performed. Measures were also obtained for the straight leg raise, passive dorsiflexion, balance, and functional tests (Five Times Sit to Stand (5TSTS), Timed Up and Go (TUG), 10-Meter Fast Walk Test (10-MFWT), and 6-Minute Walk Test (6-MWT)). The results specify that functional movement performance correlates most strongly with medial gastrocnemius muscle thickness (5TSTS (r = −0.26), TUG (r = −0.44), 10-MFWT (r = 0.41), and 6-MWT (r = 0.48) all p < 0.05) and that vastus lateralis muscle thickness and medial gastrocnemius muscle thickness correlate positively with balance ability (r = 0.24, 0.34; p < 0.05) and negatively with fear of falling. It appears that muscle mass, rather than other morphological parameters, such as muscle quality or fascicle length, is the main factor affecting the susceptibility of older women to frailty.
Topics: Humans; Female; Aged; Muscle Strength; Fear; Thailand; Muscle, Skeletal; Ultrasonography
PubMed: 36498173
DOI: 10.3390/ijerph192316099 -
ELife Oct 2022Hepatic sarcopenia is one of many complications associated with chronic liver disease (CLD) and has a high mortality rate; however, the liver-muscle axis is not fully...
Association of lithocholic acid with skeletal muscle hypertrophy through TGR5-IGF-1 and skeletal muscle mass in cultured mouse myotubes, chronic liver disease rats and humans.
BACKGROUND
Hepatic sarcopenia is one of many complications associated with chronic liver disease (CLD) and has a high mortality rate; however, the liver-muscle axis is not fully understood. Therefore, few effective treatments exist for hepatic sarcopenia, the best of which being branched-chain amino acid (BCAA) supplementation to help increase muscle mass. Our aim was to investigate the molecular mechanism(s) of hepatic sarcopenia focused on bile acid (BA) composition.
METHODS
The correlation between serum BA levels and psoas muscle mass index (PMI) was examined in 73 CLD patients. Gastrocnemius muscle phenotype and serum BA levels were assessed in CLD rats treated with BCAA. Mouse skeletal muscle cells (C2C12) were incubated with lithocholic acid (LCA), G-protein-coupled receptor 5 (TGR5) agonist or TGR5 antagonist to assess skeletal muscle hypertrophy.
RESULTS
In human CLD, serum LCA levels were the sole factor positively correlated with PMI and were significantly decreased in both the low muscle mass group and the deceased group. Serum LCA levels were also shown to predict patient survival. Gastrocnemius muscle weight significantly increased in CLD rats treated with BCAA via suppression of protein degradation pathways, coupled with a significant increase in serum LCA levels. LCA treated C2C12 hypertrophy occurred in a concentration-dependent manner linked with TGR5-Akt pathways based upon inhibition results via a TGR5 antagonist.
CONCLUSIONS
Our results indicate LCA-mediated skeletal muscle hypertrophy via activation of TGR5-IGF1-Akt signaling pathways. In addition, serum LCA levels were associated with skeletal muscle mass in cirrhotic rats, as well as CLD patients, and predicted overall patient survival.
FUNDING
This research was supported by JSPS KAKENHI Grant Number 22K08011 and 21H02892, and AMED under Grant Number JP21fk0210090 and JP22fk0210115. Maintaining cirrhotic rats were partially supported by Otsuka Pharmaceutical Company.
Topics: Amino Acids, Branched-Chain; Animals; Bile Acids and Salts; Humans; Hypertrophy; Insulin-Like Growth Factor I; Lithocholic Acid; Liver Cirrhosis; Liver Diseases; Mice; Muscle Fibers, Skeletal; Muscle, Skeletal; Proto-Oncogene Proteins c-akt; Rats; Receptors, G-Protein-Coupled; Sarcopenia
PubMed: 36206032
DOI: 10.7554/eLife.80638 -
Journal of Electromyography and... Jun 2023The mathematical muscle models should include several aspects of muscle structure and physiology. First, muscle force is the sum of forces of multiple motor units (MUs),... (Review)
Review
The mathematical muscle models should include several aspects of muscle structure and physiology. First, muscle force is the sum of forces of multiple motor units (MUs), which have different contractile properties and play different roles in generating muscle force. Second, whole muscle activity is an effect of net excitatory inputs to a pool of motoneurons innervating the muscle, which have different excitability, influencing MU recruitment. In this review, we compare various methods for modeling MU twitch and tetanic forces and then discuss muscle models composed of different MU types and number. We first present four different analytical functions used for twitch modeling and show limitations related to the number of twitch describing parameters. We also show that a nonlinear summation of twitches should be considered in modeling tetanic contractions. We then compare different muscle models, most of which are variations of Fuglevand's model, adopting a common drive hypothesis and the size principle. We pay attention to integrating previously developed models into a consensus model based on physiological data from in vivo experiments on the rat medial gastrocnemius muscle and its respective motoneurons. Finally, we discuss the shortcomings of existing models and potential applications for studying MU synchronization, potentiation, and fatigue.
Topics: Rats; Animals; Muscle, Skeletal; Muscle Contraction; Motor Neurons; Electric Stimulation
PubMed: 37099899
DOI: 10.1016/j.jelekin.2023.102774 -
PloS One 2021Ultrasonography is widely used to measure gastrocnemius muscle architecture; however, it is unclear if values obtained from digitised images are sensitive enough to...
Ultrasonography is widely used to measure gastrocnemius muscle architecture; however, it is unclear if values obtained from digitised images are sensitive enough to track architectural responses to clinical interventions. The purpose of this study was to explore the reliability and determine the minimal detectable change (MDC) of gastrocnemius medialis (GM) and gastrocnemius lateralis (GL) muscle architecture using ultrasound in a clinical setting. A trained sonographer obtained three B-mode images from each of the GM and GL muscles in 87 volunteers (44 males, 43 females; 22±9 years of age) on two separate occasions. Three independent investigators received training, then digitised the images to determine intra-rater, inter-rater, and test-retest reliability for fascicle length (FL), pennation angle (θ) and muscle thickness. Median FL, θ, and muscle thickness for GM and GL were 53.6-55.7 mm and 65.8-69.3 mm, 18.7-19.5° and 11.9-12.5°, and 12.8-13.2 mm and 15.9-16.9 mm, respectively. Intra- and inter-rater reliability of manual digitisation was excellent for all parameters. Test-retest reliability was moderate to excellent with intraclass correlation coefficient (ICC) values ≥0.80 for FL, ≥0.61 for θ, and ≥0.81 for muscle thickness, in both GM and GL. The respective MDC for GM and GL FL, θ, and muscle thickness was ≤12.1 mm and ≤18.00 mm, ≤6.4° and ≤4.2°, and ≤3.2 mm and ≤3.1 mm. Although reliable, the relatively large MDC suggest that clinically derived ultrasound measurements of muscle architecture in GM and GL are more likely to be useful to detect differences between populations than to detect changes in muscle architecture following interventions.
Topics: Adolescent; Adult; Female; Humans; Male; Muscle, Skeletal; Reproducibility of Results; Ultrasonography; Young Adult
PubMed: 34587209
DOI: 10.1371/journal.pone.0258014