scholarly journals Myosin Isoforms and Contractile Properties of Single Fibers of Human Latissimus Dorsi Muscle

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Antonio Paoli ◽  
Quirico F. Pacelli ◽  
Pasqua Cancellara ◽  
Luana Toniolo ◽  
Tatiana Moro ◽  
...  
Keyword(s):  
Latissimus Dorsi ◽  
Fiber Type ◽  
Myosin Heavy Chain Isoforms ◽  
Latissimus Dorsi Muscle ◽  
Myosin Isoforms ◽  
Cross Sectional ◽  
Type Distribution ◽  
Dorsi Muscle ◽  
Fiber Type Distribution

The aim of our study was to investigate fiber type distribution and contractile characteristics of Latissimus Dorsi muscle (LDM). Samples were collected from 18 young healthy subjects (9 males and 9 females) through percutaneous fine needle muscle biopsy. The results showed a predominance of fast myosin heavy chain isoforms (MyHC) with 42% of MyHC 2A and 25% of MyHC 2X, while MyHC 1 represented only 33%. The unbalance toward fast isoforms was even greater in males (71%) than in females (64%). Fiber type distribution partially reflected MyHC isoform distribution with 28% type 1/slow fibers and 5% hybrid 1/2A fibers, while fast fibers were divided into 30% type 2A, 31% type A/X, 4% type X, and 2% type 1/2X. Type 1/slow fibers were not only less abundant but also smaller in cross-sectional area than fast fibers. During maximal isometric contraction, type 1/slow fibers developed force and tension significantly lower than the two major groups of fast fibers. In conclusion, the predominance of fast fibers and their greater size and strength compared to slow fibers reveal that LDM is a muscle specialized mainly in phasic and powerful activity. Importantly, such specialization is more pronounced in males than in females.

Role of protein intake on protein synthesis and fiber distribution in the unweighted soleus muscle

1993 ◽  
Vol 75 (3) ◽  
pp. 1226-1232 ◽  
Author(s):  
D. Taillandier ◽  
X. Bigard ◽  
D. Desplanches ◽  
D. Attaix ◽  
C. Y. Guezennec ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Soleus Muscle ◽  
Protein Intake ◽  
Fiber Type ◽  
Weight Bearing ◽  
Type I ◽  
Fiber Distribution ◽  
Cross Sectional ◽  
Type Distribution ◽  
Fiber Type Distribution

Protein turnover in skeletal muscle is very sensitive to protein intake. To examine whether protein intake is able to affect protein synthesis in the atrophied soleus muscle, the effects of a high-protein (30%, HP) and a medium-protein (15%, MP) diet were studied in rats after 21 days of hindlimb unweighting. Three weeks of unweighting induced a sharp decrease in food intake (30%). The fractional rate of protein synthesis (ks) was determined in vivo in the slow-twitch soleus muscle by use of a flooding-dose method. With respect to pair-fed animals, a significant reduction in ks occurred (33%) in MP non-weight-bearing rats, whereas it was of lesser magnitude and not significant in HP rats. In the atrophied soleus muscle of non-weight-bearing MP rats, a large decrease (42%) in type I fiber distribution was accompanied by an increase in intermediate and type IIa fibers. By contrast, a higher percentage of type I fiber was maintained with the HP diet. However, the HP diet had no beneficial effect in preventing the decrease in either type I fiber cross-sectional area (65%) or the average decrease in absolute myofibrillar and mitochondrial volumes (69 and 52%, respectively). These results demonstrate that an HP intake did not prevent soleus muscle atrophy but may sustain protein synthesis and partly preserve fiber type distribution without affecting the ultrastructural composition of fibers. Because the circulating level of free 3,5,3'-triiodothyronine was reduced by 14% with the HP diet, this effect on fiber type distribution, and possibly protein synthesis, may involve thyroid hormones.

scholarly journals EMG Analysis of Dominant and Non-Dominant Arm of Latissimus Dorsi Muscles in Bowlers of Karad, Maharashtra, India

2021 ◽  
Vol 10 (36) ◽  
pp. 3088-3093
Author(s):  
Pradip Raghunath Lad ◽  
Dhairysheel Sanjay Patil ◽  
Smita Chandrakant Patil ◽  
Khushboo Trishant Chotai
Keyword(s):  
Latissimus Dorsi ◽  
Surface Emg ◽  
Latissimus Dorsi Muscle ◽  
Wilcoxon Test ◽  
Peak Amplitude ◽  
Emg Activity ◽  
Cross Sectional ◽  
Dorsi Muscle ◽  
Muscular Structure ◽  
Emg Electrodes

BACKGROUND Latissimus dorsi plays an important role in bowlers. Different bowling techniques recruit latissimus dorsi at different phases of bowling. This causes the muscle to undergo excessive contraction than its limit. Despite widespread knowledge about the recruitment of latissimus dorsi in bowling, there is limited electromyographic (EMG) studies about latissimus dorsi. It is necessary to evaluate and document the recruitment of latissimus dorsi in dominant and non-dominant arm in bowlers, which is focused in this study. This study was done to analyse the surface EMG activity of latissimus dorsi muscle in dominant and non-dominant arm during bowling. METHODS A cross-sectional analytical study was carried out among 96 professional cricket bowlers from deluxe cricket club and Yashwanthrao Chavan’s cricket club in Karad. EMG electrodes were applied over the latissimus dorsi muscle and the bowlers were asked to perform the action of bowling. The root mean square (RMS) and mean peak amplitude of the dominant and non-dominant arm were recorded. RESULTS The RMS (12.45 ± 2.84) values and mean peak amplitude (131.77 ± 44.11) of the dominant latissimus dorsi varied significantly from non-dominant muscle (P = 0.0015). Wilcoxon test was utilized for analysis of within group parameters. CONCLUSIONS The result of the present study showed strong evidence to support high recruitment of dominant latissimus dorsi in professional bowlers suggests the changes occurred in the physiological as well as biomechanical muscular structure. KEY WORDS EMG, Dominant, Non-Dominant, Latissimus Dorsi, Fast Bowlers

Fiber-type distribution and expression of myosin heavy chain isoforms in newborn heterozygous myostatin-knockout pigs

2017 ◽  
Vol 39 (12) ◽  
pp. 1811-1819 ◽  
Author(s):  
Xiao-Xu Xing ◽  
Mei-Fu Xuan ◽  
Long Jin ◽  
Qing Guo ◽  
Zhao-Bo Luo ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Fiber Type ◽  
Myosin Heavy Chain Isoforms ◽  
Type Distribution ◽  
Fiber Type Distribution

scholarly journals MyoSight—semi-automated image analysis of skeletal muscle cross sections

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Lyle W. Babcock ◽  
Amy D. Hanna ◽  
Nadia H. Agha ◽  
Susan L. Hamilton
Keyword(s):  
Skeletal Muscle ◽  
Image Analysis ◽  
Cross Sections ◽  
Fiber Type ◽  
Sectional Area ◽  
Cross Sectional ◽  
Type Distribution ◽  
Central Nuclei ◽  
Fiber Size ◽  
Fiber Type Distribution

Abstract Background Manual analysis of cross-sectional area, fiber-type distribution, and total and centralized nuclei in skeletal muscle cross sections is tedious and time consuming, necessitating an accurate, automated method of analysis. While several excellent programs are available, our analyses of skeletal muscle disease models suggest the need for additional features and flexibility to adequately describe disease pathology. We introduce a new semi-automated analysis program, MyoSight, which is designed to facilitate image analysis of skeletal muscle cross sections and provide additional flexibility in the analyses. Results We describe staining and imaging methods that generate high-quality images of immunofluorescent-labelled cross sections from mouse skeletal muscle. Using these methods, we can analyze up to 5 different fluorophores in a single image, allowing simultaneous analyses of perinuclei, central nuclei, fiber size, and fiber-type distribution. MyoSight displays high reproducibility among users, and the data generated are in close agreement with data obtained from manual analyses of cross-sectional area (CSA), fiber number, fiber-type distribution, and number and localization of myonuclei. Furthermore, MyoSight clearly delineates changes in these parameters in muscle sections from a mouse model of Duchenne muscular dystrophy (mdx). Conclusions MyoSight is a new program based on an algorithm that can be optimized by the user to obtain highly accurate fiber size, fiber-type identification, and perinuclei and central nuclei per fiber measurements. MyoSight combines features available separately in other programs, is user friendly, and provides visual outputs that allow the user to confirm the accuracy of the analyses and correct any inaccuracies. We present MyoSight as a new program to facilitate the analyses of fiber type and CSA changes arising from injury, disease, exercise, and therapeutic interventions.

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