How Do Muscles Grow? – Part 4

Before we begin Part Four I wanted to remind you that in Part One we looked at the processes that occur during training that influence muscle growth and the recovery mechanisms that our body uses to begin the process of repair. In Part Two we focused on the breakdown process of the damaged muscle and the process of muscle growth including looking at some of the growth factors our body uses to complete this process. In Part Three we looked at those growth factors in a lot more detail and learned how things like testosterone and IGF-1 directly influence muscle-building. Today I’m going to look at some more factors that are involved in the muscle growth process and see what can be learned and used to our advantage in our quest for more muscle.

For any metabolic process within the cell ATP is necessary as the source of energy to enable the process to occur. If there isn’t enough ATP to fuel the necessary action then several cellular processes significantly slow down, meaning that the entire function of the cell is less than optimal. The removal of waste products, recovery from training and protein synthesis all become compromised due to the lack of ATP. Research has shown that if the contractile components of the cell continue to grow without enough ATP available to supply the systems of each cell, such as the mitochondria, then this cellular slow down will occur.

What this means when this happens is that the contractile elements of the muscle cell has grown too large for the energy systems in the sarcoplasm to support it any longer. This has been shown to happen through a poor training program as well. How this can happen is if the full strength of the muscle is unable to exert itself due to the cell being unable to produce and utilize enough momentary ATP to cycle the actin/myosin cross-bridges adequately. The same is true when hypertrophy and strength training stimulates these muscle cells but because the cell doesn’t have enough energy to create new proteins and support them, muscle growth does not occur.

For the record, muscle is constantly broken down and rebuilt. It is simply known as muscle maintenance. All of the above is what is known to most of us as a training plateau. In this case you may be stimulating muscle mass growth but because the cell is not able to adapt, a condition known as irrational hypertrophy is present (simply meaning that you should be growing but aren’t). Cells in this state contain significantly larger mitochondria than if they were untrained, but fewer of them per myofibril. This means that ATP cannot possibly be created fast enough for the muscle cells to use.

The opposite of this is when weight training results in vascular improvements within the cell, meaning the mitochondrial density increases, then a plateau will not occur and the training stimulated hypertrophy can carry on unimpeded. This is referred to as rational hypertrophy and is an ideal situation. This further illustrates the importance of training for sarcoplasmic hypertrophy, as the energy systems that feed the muscle will need to be built before the muscle is able to grow, not the other way around as many think. Put another way, you can’t fuel your workout effectively without having enough glycogen available. You can’t fuel it afterward, as it is over at that point and the opportunity has been passed by.

What rep range is optimal for building muscle then? Well, heavy weights are often said to be ideal but if the weight is too heavy that too few reps are performed then muscular failure will occur before the growth stimulus has been sent to the muscle cells. It is also true that very few muscle cells will be under tension for long enough to affect them. This is why powerlifters and Olympic lifters are never as big as bodybuilders, even thought they are often stronger. They are training a smaller percentage of their muscle fibers to failure and very few muscle cells will receive the message that growth is needed.

A set of eight or more reps will deliver much more stimulus to the muscle cell because a much larger number of muscle fibers have reached failure and a message will be sent to a larger number of muscle cells that growth must occur. Also, when training in the higher rep ranges there are substrates (a molecule upon which an enzyme acts) like phosphate and hydrogen ions that build up in the muscles, and it has been suggested that these substrates assist in the muscle growth process as well. This means that while these high rep sets may not directly contribute to muscle growth, the substrates that they produce do. Muscle-building is not as simple an equation as one plus one equals two. Our body’s are complex organism and the processes within them are as well.

This is all evidence as to why bodybuilders have much larger muscles than strength athletes. Training for strength stimulates the nervous system to better increase its efficiency to produce greater strength and recruitment patterns, without actually increasing muscle size, where as bodybuilders train long enough to build the energy systems needed for growth and adequately stimulate the muscle fibers as well.

I’m going to be revisiting most of what was talked about here today in a series coming up about functional hypertrophy. As we can see, there clearly exists many benefits to building the energy systems that directly feed the muscle, even if doing so does not immediately contribute to strength or muscle growth. There are still more factors involved in muscle growth to be looked at next week. I’ll continue then and begin the next series as well when we next meet. Until then my friends,

Happy Lifting!

Related Reading

Eating Too Much Can Impair Muscle Growth?

Testosterone: Anabolic Response

Muscle: Hormones and Weights

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