We keep moving forward and digging deeper into
the area of the ADVANCED block topics. We do hope that our posts are not too complex. If you cannot understand something try reading it again and then ask a question. Today’s topic is one the most exciting for our participants.
It is worth mentioning that it is not yet discovered exactly how muscles grow, there is no
an established opinion among scientists if it is because of new fibres or just thickening of the existing ones or splitting and thickening and how much of it is hard-wired by genes.
Nonetheless, there are four factors which are prerequisite for muscle growth. We use the word ‘factors’ since exact relationship between factors and growth is not yet established in its fullness. That is they work, it is been tested and proved, but why exactly they work it still remains unclear.
1 Cellular amino acids stores
Every protein structure, which includes muscle tissue, uses amino acids as building blocks. The amount of amino acids in the cell is accumulated gradually. The whole pool of free amino acids
in the body is called
the amino acid pool. Hence there is no need to increase
the (можно и без) level of amino acids in
the blood stream during exercise. Since most intensive protein synthesis happens in the first 24 hours after the exercise
, you need to provide fuel for this. Protein synthesis returns to base level in 36-72 hours after exercise, according to various research.
2 This factor is most important since it triggers the process of protein synthesis in miofibrils. Anabolic hormone level is, in its turn, triggered through physiological stress from exercise to failure (?). During the exercise hormones
enter the cell, gradually accumulating there. The more sets
are done the higher the level of hormones in the cell.
Hormones set off
the process of transcribing DNA information into messanger-RNA (mRNA). Then mRNA with the help of transport RNA (tRNA) and ribosomal RNA (rRNA) is translated into
a complete protein. Anabolic hormones do not leave the cell and are metabolised within the cell within days.
3 Increase in free creatine level within muscle fibres
Accumulation of free creatine (Cr) in sarcoplasm of the cell (non contracting part of the fibre) is the criterium of intensified metabolism in the cell. Creatine phosphate (CP) transfers energy from mitochondria to myofibrils in Type I (oxidative, red, slow) fibres and from sarcoplasmic Adenosine TriPhosphate (ATP) to myofibrillic ATP in Type II (glycolitic, white, fast) fibres. It also
supplies energy
to the nucleus of the cell. If a fibre is activated then the cell spends ATP as well as the nucleus and the cell needs CP to recombine Adenosine DiPhsphate (ADP) back into ATP. Besides, ATP is the only energy source in the cell. The nucleus needs energy in the form of ATP to create mRNA and ribosomes. Spent CP is released back into sarcoplasm in
the form of free creatine (Cr) and phosphate. However, the most important role of Cr if to provide energy for RNA synthesis triggered by hormones. The more free Cr is around the more intensive the process is. While the cell is not active it contains almost 100% of Cr in the form of CP
and metabolism and synthesis are slow.
All organelles (subunits of the cell) are being incessantly renewed but physical stress activates the fibre forces more creatine to be released into sarcoplasm in the form of free Cr (плохой источник на русском, неясна связь между двумя событиями: Хотя все органеллы организма регулярно обновляются (то есть этот процесс идет всегда), но в результате тренировки, приводящей к активности мышечного волокна, в саркоплазматическом пространстве происходит накопление свободного креатина.). It triggers metabolic process and synthesis. CP releases its energy within the nucleus and then in the form of free Cr moves to mitochondria where it is recombined back into CP. (обрезал последнее предложение - какое-то оно прямо скажем мутноватое)
4 Increase in level of hydrogen ions within myofibrils
Energy expenditure during intensive exercise causes increase in concentration of hydrogen ions (H+) in the cell. Moderate concentration of H+ ions makes cell membranes more transparent to hormones and activates cell enzymes, thus creating grounds for protein synthesis. This process does not happen in Type I (slow, red, oxydative) fibres since the high number of mitochondria continue to consume oxygen and the cell works aerobically, effectively preventing increase in concentration of free H+ ions, thus eliminating the fourth factor of muscle growth from establishing itself within the cell (слишком много -ing, некрасиво но пока без идей).
часть Селуянова не стал переводить про импульсы и т.п. Не во всём Селуянове я уверен
New myofibrils are grown within 7-15 days but the most active synthesis happends during the training session and in the first hours right after it. H+ do most of the work while training and
then for an hour after. Hormones help to create new RNAs and proteins for 2-3 days more but this process is much less intensive than during training, when this process is also helped by higher concentration of free creatine (Cr).