World of big muscles

2/08/2011

Types of muscle fibers

Types of muscle fibers

There are three types of muscle fibers. Slow fibers are known as Type I. They are red because of the fact that they contain high amounts of red myoglobin. These fibers are characterized by relatively long time reduction, low peak power and high resistance to fatigue. They contain a large number of mitochondria, which oxidize and carbohydrates and fatty acids to restore ATP, which is especially good for long competition. In biochemical terms, these fibers have a large number of oxidative enzymes and the low number of glycolytic, in these fibers is very low ATPase activity (an enzyme that participates in the cleavage of ATP).

Fast-twitch muscle fibers are white, they are stored inside a large amount of glycogen (chains of glucose molecules) and ATP to generate energy and have a relatively fast time reduction. Fast fibers are in turn divided into two types: fast oxidative-glycolytic (pink, Type IIa), with an average resistance to fatigue and glycolytic (white, type IIb), with low resistance to fatigue. Type IIa fibers are able to maintain performance even after a large number of abbreviations, these fibers are rich in both oxidative and glycolytic enzymes, and ATPase. Type IIb Fibers fast fatigued, but can produce a very large amount of power for a few contractions without rest. These fibers are used for energy glycolysis and the splitting of ATP ATPase.


Despite the fact that genes determine the basic composition and muscle physiology, through training, you can change and the type of metabolism and the size of fibers and the size of capillarization. The fibers are adapted to the stress, which they are subjected to during training. The type of training will affect the changes that will occur in them. But the change will be subject to only those components of the muscle fibers themselves (organelles, enzymes, etc.), which are experiencing load higher than the threshold, they could make. For example mitochondria will grow in size and number only if they would be adequate aerobic stress.

With a stable and correctly picked endurance training, both types of fibers increased their aerobic properties through an increase in the number and size of mitochondria, a greater number of oxidative enzymes, increasing the stored directly into the fibers of fat (for faster access to the source of energy), reducing the production of lactate. When strength training, anaerobic fibers increase opportunities and improve the opportunities for recycling of glycogen, ATP and CP, in addition fast fibers are more grow in size, rather than slow. However, studies do not confirm the claim that you can convert one fiber to another.

If you do endurance training, it will increase capacity to burn fat, preservation of carbohydrates, the concentration of lactic acid will grow more slowly. 2-3 months training will increase the density of capillaries and blood flow through the slow fibers, whereas fast glycolytic fibers would receive less blood.

If you do moderate strength training, cross-sectional area of both types of fibers will increase, which in turn will lead to an increase in strength. If the power training will be intense, the thickness will grow almost exclusively fast fibers, and thus they will lose in the density of mitochondria.

Types of muscle fibers

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