scholarly journals Effect of pedaling rates and myosin heavy chain composition in the vastus lateralis muscle on the power generating capability during incremental cycling in humans

2008 ◽  
pp. 873-884
Author(s):  
J Majerczak ◽  
Z Szkutnik ◽  
K Duda ◽  
M Komorowska ◽  
L Kolodziejski ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Vastus Lateralis ◽  
Incremental Exercise ◽  
Vastus Lateralis Muscle ◽  
Lower Content ◽  
Lateralis Muscle ◽  
Chain Composition ◽  
Myosin Heavy Chain Composition

In this study, we have determined power output reached at maximal oxygen uptake during incremental cycling exercise (P(I, max)) performed at low and at high pedaling rates in nineteen untrained men with various myosin heavy chain composition (MyHC) in the vastus lateralis muscle. On separate days, subjects performed two incremental exercise tests until exhaustion at 60 rev min(-1) and at 120 rev min(-1). In the studied group of subjects P(I, max) reached during cycling at 60 rev min(-1) was significantly higher (p=0.0001) than that at 120 rev min(-1) (287+/-29 vs. 215+/-42 W, respectively for 60 and 120 rev min(-1)). For further comparisons, two groups of subjects (n=6, each) were selected according to MyHC composition in the vastus lateralis muscle: group H with higher MyHC II content (56.8+/-2.79 %) and group L with lower MyHC II content in this muscle (28.6+/-5.8 %). P(I, max) reached during cycling performed at 60 rev min(-1) in group H was significantly lower than in group L (p=0.03). However, during cycling at 120 rev min(-1), there was no significant difference in P(I, max) reached by both groups of subjects (p=0.38). Moreover, oxygen uptake (VO(2)), blood hydrogen ion [H(+)], plasma lactate [La(-)] and ammonia [NH(3)] concentrations determined at the four highest power outputs completed during the incremental cycling performed at 60 as well as 120 rev min(-1), in the group H were significantly higher than in group L. We have concluded that during an incremental exercise performed at low pedaling rates the subjects with lower content of MyHC II in the vastus lateralis muscle possess greater power generating capabilities than the subjects with higher content of MyHC II. Surprisingly, at high pedaling rate, power generating capabilities in the subjects with higher MyHC II content in the vastus lateralis muscle did not differ from those found in the subjects with lower content of MyHC II in this muscle, despite higher blood [H(+)], [La(-)] and [NH(3)] concentrations. This indicates that at high pedaling rates the subjects with higher percentage of MyHC II in the vastus lateralis muscle perform relatively better than the subjects with lower percentage of MyHC II in this muscle.

scholarly journals Altered expression of myosin heavy chain in the vastus lateralis muscle in patients with COPD

1999 ◽  
Vol 13 (4) ◽  
pp. 850 ◽  
Author(s):  
F. Maltais ◽  
M.J. Sullivan ◽  
P LeBlanc ◽  
B.d Duscha ◽  
F.h Schachat ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Vastus Lateralis ◽  
Vastus Lateralis Muscle ◽  
Altered Expression ◽  
Lateralis Muscle

scholarly journals Myofibril and Mitochondrial Area Changes in Type I and II Fibers Following 10 Weeks of Resistance Training in Previously Untrained Men

2021 ◽  
Vol 12 ◽  
Author(s):  
Bradley A. Ruple ◽  
Joshua S. Godwin ◽  
Paulo H. C. Mesquita ◽  
Shelby C. Osburn ◽  
Casey L. Sexton ◽  
...  
Keyword(s):  
Resistance Training ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Vastus Lateralis ◽  
Thigh Muscle ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Cross Sectional ◽  
Lateralis Muscle ◽  
Actin Protein

Resistance training increases muscle fiber hypertrophy, but the morphological adaptations that occur within muscle fibers remain largely unresolved. Fifteen males with minimal training experience (24±4years, 23.9±3.1kg/m2 body mass index) performed 10weeks of conventional, full-body resistance training (2× weekly). Body composition, the radiological density of the vastus lateralis muscle using peripheral quantitative computed tomography (pQCT), and vastus lateralis muscle biopsies were obtained 1week prior to and 72h following the last training bout. Quantification of myofibril and mitochondrial areas in type I (positive for MyHC I) and II (positive for MyHC IIa/IIx) fibers was performed using immunohistochemistry (IHC) techniques. Relative myosin heavy chain and actin protein abundances per wet muscle weight as well as citrate synthase (CS) activity assays were also obtained on tissue lysates. Training increased whole-body lean mass, mid-thigh muscle cross-sectional area, mean and type II fiber cross-sectional areas (fCSA), and maximal strength values for leg press, bench press, and deadlift (p<0.05). The intracellular area occupied by myofibrils in type I or II fibers was not altered with training, suggesting a proportional expansion of myofibrils with fCSA increases. However, our histological analysis was unable to differentiate whether increases in myofibril number or girth occurred. Relative myosin heavy chain and actin protein abundances also did not change with training. IHC indicated training increased mitochondrial areas in both fiber types (p=0.018), albeit CS activity levels remained unaltered with training suggesting a discordance between these assays. Interestingly, although pQCT-derived muscle density increased with training (p=0.036), suggestive of myofibril packing, a positive association existed between training-induced changes in this metric and changes in mean fiber myofibril area (r=0.600, p=0.018). To summarize, our data imply that shorter-term resistance training promotes a proportional expansion of the area occupied by myofibrils and a disproportional expansion of the area occupied by mitochondria in type I and II fibers. Additionally, IHC and biochemical techniques should be viewed independently from one another given the lack of agreement between the variables assessed herein. Finally, the pQCT may be a viable tool to non-invasively track morphological changes (specifically myofibril density) in muscle tissue.

scholarly journals Myofibril and Mitochondrial Area Changes in Type I and II Fibers Following 10 Weeks of Resistance Training in Previously Untrained Men

2021 ◽  
Author(s):  
Bradley A. Ruple ◽  
Joshua S. Godwin ◽  
Paulo H. C. Mesquita ◽  
Shelby C. Osburn ◽  
Casey L. Sexton ◽  
...  
Keyword(s):  
Resistance Training ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Vastus Lateralis ◽  
Thigh Muscle ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Cross Sectional ◽  
Lateralis Muscle ◽  
Actin Protein

Resistance training increases myofiber hypertrophy, but the morphological adaptations that occur within myofibers remain largely unresolved. Fifteen males with minimal training experience (24±4 years, 17.9±1.4 kg/m2 lean body mass index) performed 10 weeks of conventional, full-body resistance training (2x weekly). Body composition, the radiological density of the vastus lateralis muscle using peripheral quantitative computed tomography (pQCT), and vastus lateralis muscle biopsies were obtained one week prior to and 72 hours following the last training bout. Fiber typing and the quantification of myofibril and mitochondrial areas per fiber were performed using histology/immunohistochemistry (IHC) techniques. Relative myosin heavy chain and actin protein abundances per wet muscle weight as well as citrate synthase (CS) activity assays were also obtained on tissue lysates. Training increased whole-body lean mass, mid-thigh muscle cross-sectional area, various strength metrics, and mean and type II fiber cross sectional areas (fCSA) (p<0.05). Myofibril areas in type I or II fibers were not altered with training, suggesting a proportional expansion with fCSA increases. Relative myosin heavy chain and actin protein abundances also did not change with training. IHC indicated training increased mitochondrial areas in both fiber types (p=0.018). However, CS activity levels remained unaltered with training. Interestingly, although pQCT-derived muscle density increased with training (p=0.036), suggestive of myofibril packing, a positive association existed between training-induced changes in this metric and changes in type I+II myofibril areas (r=0.600, p=0.018). Shorter-term resistance training seemingly involves a proportional expansion of myofibrils and an accelerated expansion of mitochondria in type I and II fibers. Additionally, histological and biochemical techniques should be viewed independently from one another given the lack of agreement between the variables assessed herein. Finally, the pQCT may be a viable tool to non-invasively track morphological changes in muscle tissue.

Effects of increased occlusal vertical dimension on daily activity and myosin heavy chain composition in rat jaw muscle

2009 ◽  
Vol 54 (8) ◽  
pp. 783-789 ◽  
Author(s):  
Yoshiki Ohnuki ◽  
Nobuhiko Kawai ◽  
Eiji Tanaka ◽  
Geerling E.J. Langenbach ◽  
Kazuo Tanne ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Daily Activity ◽  
Vertical Dimension ◽  
Jaw Muscle ◽  
Chain Composition ◽  
Occlusal Vertical Dimension ◽  
Myosin Heavy Chain Composition
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