Exemplos de uso de Type II fibers em Inglês e suas traduções para o Português
{-}
-
Colloquial
-
Official
-
Medicine
-
Financial
-
Ecclesiastic
-
Ecclesiastic
-
Computer
-
Official/political
Type II fibers fast contraction can be subdivided into types IIA and IIB.
These results suggest an important phase in which there seems to be greater recruiting of type II fibers after the AT.
In the body, Type II fibers are the second most highly myelinated fibers. .
For instance, Petrofsky et al. observed in an experiment using cats,higher concentrations of K in the type II fibers during exertion.
According to Dahmane et al. type II fibers are more numerous in the H muscles than in the Q muscles.
Such results reinforce the hypothesis that individuals with chronic ADL lesion present type II fibers atrophy in the quadriceps muscle.
Type II fibers may be transformed into type I fibers through training. On the other hand, the inverse cannot happen.
The fact that male individuals bite stronger may be related to a bigger transversal section of type II fibers.
Type II fibers connect to nuclear chain fibers and static nuclear bag fibers in muscle spindles, but not to dynamic nuclear bag fibers. .
The gastrocnemius is a mixed muscle,but with predominance of type II fibers, in which the capacity of fat uptake and oxidation, such as IMTG, is very low.
Type II fibers are more tiring; they present a large quantity of glycolytic enzymes, a small concentration of mitochondria which gives them a low aerobic potential.
This argument is in accordance with the literature which indicate higher muscle fatigue rate in young adults, whom possess relatively higher muscle strength andhigher proportion of type II fibers, when compared to older adults.
They include decreases in muscle mass cross-sectional area,mainly of type II fibers found in studies on mice and humans, decreases in oxidative metabolism, decreases in muscle protein synthesis and decreases in calcium plasmatic concentration.
This reduces the risk of falls among older adults through enhancing coordination and balance, increasing the recruitment of motor neurons and boosting the resistance to muscle fatigue and hypertrophy,particularly of type II fibers.
Since there is a more accentuated decline of type II fibers glycolytic, of fast contraction in elderly people, both in the number and in size of these fibers, this alteration could explain the greater decline of the flexor torque, leading to muscle imbalance of the knee joint.
Opposed to aerobic exercise, in which glycolytic fibers are only recruited during high-intensity exercises,electrostimulation activates all muscle fibers. Type II fibers are the first to be recruited, which improves resistance to fatigue earlier.
Coyle et al. found significant increases in the site of type II fibers only for the fast training group 5.24 rad·s, while Ewing et al. found increases in sites of type I and IIa fibers for both groups 1.05 and 4.19 rad·s, with no increases in the site of the type IIb fibers. .
Kryger and Andersen demonstrated the efficacy in improving muscle strength in the elderly after conducting an exercise program with 80% of the one-repetition maximum 1RM over a period of 12 weeks.The authors observed an increase in the size of the type II fibers measured by biopsy.
Due to a different recruiting pattern of muscular fibers, it is possible that in response to the CM,the higher lactate production by type II fibers was compensated for greater removal of this lactate by the type I fibers, a fact which ay have been accelerated by the increase of blood flow.
In another experimental study, in which the medial gastrocnemius muscle of cats was stimulated with a 20-HZ frequency, there was a higher number of type I fibers and few type IIA fibers after 56 days of stimulation, and only type I fibers after 76 days of stimulation,confirming that increase in oxidative potential was followed by loss in high glycolytic enzyme activity of type II fibers.
In 2003, Zhang et al. associated muscular efficiency with the superior presence of type I fiber, influenced by the I allele,while the DD genotype was allegedly related to the presence of type II fibers, proving maximum strength in the muscles where this type of fiber predominates, such as the quadriceps.
Although this is an assumption, it should be remembered that, in the elderly,a greater muscle deficit occurs in type II fibers. Frail and pre-frail elderly, because they have greater vulnerability and clinical instability, probably show greater muscle involvement and, presumably, respond quickly and positively to interventions, which may explain the results observed in this study.
It is known that muscles with higher percentages of fast contraction fibers type II are more prone to fatigue. In the case of lower limbs,there is evidence that there is higher percentage of type II fibers in the vastus lateralis muscle; hence, lower resistance to fatigue is expected.
The skeletal musculature of HF patients presents type I and II fibers with reduced diameters. Atrophy occurs in the type II fibers, and idiopathic myopathies and hypotrophy affect the type I fibers. However, the etiology of these primary cardiac muscle or skeletal myopathies or secondary alterations related to HF is still not clear.
The etiology of sarcopenia involves various factors, such as loss of motor neurons and cell apoptosis, resulting in a considerable decrease in the number of muscle fibers, especially those for rapid contraction type II fibers, leading to diminished strength and functional quality of the skeletal muscle.
Similarly, as there was no determination of the training speed, one can assume that the program performance, as it was proposed, may have increased the gain of type II fibers. In this context, Kryger and Andersen, after a training program with 80% of 1RM, for 12 weeks, observed an increase in the size of type II fibers, with gains in muscle strength and improvement in the angle to reach the peak of torque.
Another relevant aspect that would justify the use of creatine in patients with COPD is that this population presents redistribution of types of muscle fibers, with predominance of type II fibers, which are characterized by rapid contractions and present greater anaerobic capacity than do type I fibers. Studies reveal that type II fibers use more phosphocreatine during exercise.
This decline in muscle strength is associated with the degree of type II fiber atrophy and, usually, is not limited to the lower limbs.
Since the tibialis anterior is classified as a muscle with predominance of type II fiber, with approximately 90%, it would be more dependent on the glycidic metabolism.
This overload in the chronic lesion could lead to changes in fibers type, triggering hence, type II fiber atrophy and resulting in a decrease of the Fmed.