Muscle Growth |
This discussion clearly shows that muscle growth is a complex molecular biology cell process involving the interplay of numerous cellular organelles and growth factors, occurring as a result of resistance exercise. However, for client education some important applications need to be summarized:
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How to build muscle?
Sarcoplasmic Hypertrophy
Increasing the volume of the tissue that supplies energy to the muscle or is involved with the neural drive: Intimately involved in the production of ATP are intracellular bodies called ‘mitochondria’. Muscle fibers will adapt to high volume (and higher rep) training sessions by increasing the number of mitochondria in the cells. They will also increase the concentrations of the enzymes involved in the oxidative phosphorylation and anaerobic glycolysis mechanisms of energy production and increase the volume of sarcoplasmic fluid inside the cell (including glycogen) and also the fluid between the actual cells. This type of hypertrophy produces very little in the way of added limit strength but has profound effects on increasing strength-endurance (the ability to do reps with a certain weight) because it dramatically increases the muscles’ ability to produce ATP. Adaptations of this sort are characteristic of Bodybuilders’ muscles. It should also be obvious that as the volume of the tissue that supplies energy to the muscle represents only around 20% of the total muscle cell volume in untrained individuals, this isn’t where the majority of growth potential lies.
Hypertrophy Factor
Sarcoplasmic hypertrophy of muscle cells does directly produce moderate increases in size. But also, ATP is the source of energy for all muscular contraction – type II fibers included. Wouldn’t having more of this in the muscle, and having the ability to produce greater intramuscular quantities at any one time, be an asset? The answer is, clearly, “yes”. That’s where a major portion of the importance of sarcoplasmic hypertrophy comes into Bodybuilding. As for increasing the tissue that is involved with the neural drive, this would theoretically occur in response to the need for contracting cells with hypertrophied contractile machinery. Directly, it would produce very little in the way of added size. In addition, there are other intracellular bodies whose growth and/or proliferation would fall under the category of sarcoplasmic hypertrophy. These would be organelles such as the ribosomes, which are involved in protein synthesis. As in the case of neural drive machinery, in most cases they would increase in size or number only to support sarcomere hypertrophy. They would have little direct impact on overall muscle size.
Sarcomere Hypertrophy
Increasing the volume of contractile machinery: The vast majority of the volume of each muscle cell (~80%) is made up of contractile machinery. Therefore, therein lies the greatest potential for increasing muscle cell size. Trained muscle responds by increasing the number of actin/myosin filaments (sarcomeres) that it contains – this is, primarily, what is responsible for the increased strength and size. But before a muscle will grow like this it has to be ‘broken down’.
Increasing the volume of the tissue that supplies energy to the muscle or is involved with the neural drive: Intimately involved in the production of ATP are intracellular bodies called ‘mitochondria’. Muscle fibers will adapt to high volume (and higher rep) training sessions by increasing the number of mitochondria in the cells. They will also increase the concentrations of the enzymes involved in the oxidative phosphorylation and anaerobic glycolysis mechanisms of energy production and increase the volume of sarcoplasmic fluid inside the cell (including glycogen) and also the fluid between the actual cells. This type of hypertrophy produces very little in the way of added limit strength but has profound effects on increasing strength-endurance (the ability to do reps with a certain weight) because it dramatically increases the muscles’ ability to produce ATP. Adaptations of this sort are characteristic of Bodybuilders’ muscles. It should also be obvious that as the volume of the tissue that supplies energy to the muscle represents only around 20% of the total muscle cell volume in untrained individuals, this isn’t where the majority of growth potential lies.
Hypertrophy Factor
Sarcoplasmic hypertrophy of muscle cells does directly produce moderate increases in size. But also, ATP is the source of energy for all muscular contraction – type II fibers included. Wouldn’t having more of this in the muscle, and having the ability to produce greater intramuscular quantities at any one time, be an asset? The answer is, clearly, “yes”. That’s where a major portion of the importance of sarcoplasmic hypertrophy comes into Bodybuilding. As for increasing the tissue that is involved with the neural drive, this would theoretically occur in response to the need for contracting cells with hypertrophied contractile machinery. Directly, it would produce very little in the way of added size. In addition, there are other intracellular bodies whose growth and/or proliferation would fall under the category of sarcoplasmic hypertrophy. These would be organelles such as the ribosomes, which are involved in protein synthesis. As in the case of neural drive machinery, in most cases they would increase in size or number only to support sarcomere hypertrophy. They would have little direct impact on overall muscle size.
Sarcomere Hypertrophy
Increasing the volume of contractile machinery: The vast majority of the volume of each muscle cell (~80%) is made up of contractile machinery. Therefore, therein lies the greatest potential for increasing muscle cell size. Trained muscle responds by increasing the number of actin/myosin filaments (sarcomeres) that it contains – this is, primarily, what is responsible for the increased strength and size. But before a muscle will grow like this it has to be ‘broken down’.