What makes muscles grow or how to make every workout effective?
Why do you need to know this? Knowing all this will help you better control and understand your feelings during strength training.
The overall goal of understanding training, as with any of my posts, is to help you focus your efforts on highly effective tools and approaches. This is the only way we can change and grow while remaining strength training enthusiasts, without turning to the gym as a full-time job.
Only by understanding can we manage.
What are the growth factors?
Today, there are three main factors of muscle growth: mechanical tension, metabolic stress and microtrauma.
Only the last two are included in this list through bed. By the residual principle. The bulk of research indicates that mechanical tension is the most important and, perhaps, the only stimulus for growth.
Mechanical stress
Mechanical tension is a force acting on the structural components of muscle fiber from the outside, against which we apply effort.
Our muscle cells have sensors that are sensitive to mechanical action. For example, they can sense that the muscles are stretched or strained. A high degree of such force and a high degree of resistance affect these sensors and they form a signal inside the cell (in the nucleus, where the DNA is stored). There, the adaptation process is launched, which we call muscle growth.
As it turns out, thanks to these sensors, muscles not only sense and react to mechanical stress, but also distinguish types of impact very well and react to it differently. For example.
If we do the splits (as much as possible), the muscles will react to it in one way. But if we take a dumbbell in our hand and bend it to an angle of 90 degrees and hold it like that for a minute, the muscles will react in a different way. And if we start lifting and lowering the dumbbell, the muscles will react in a completely different way.
Among all types of tension, muscles respond best to:
Concentric tension (contraction under load);
Eccentric tension (stretching under load);
It is still unclear which of them is dominant. It is usually considered the first, but some researchers say the second. But what is certain is that muscles respond best when both phases are present in the movement.
There are also:
Static tension (when muscles are tense but do not contract or stretch);
Static stretching;
The muscles react poorly to the last two types of load. More precisely, they require much longer exposure. If you have all the possibilities, it is easier to do a classic strength approach. Here is an example on the latest researchUntil recently, it was believed that stretching does not build muscle well. But according to the research, it turned out that it does, and not at all badly. It just requires very long and intense exposure. In the study, it was one hour a day for 8 weeks in a special device that maintains constant tension. The subjects noted a very high level of tension, pain, and rejection. This cannot be called an effective approach. Nevertheless, it works. It also provides new insight into the mechanisms of muscle growth, and researchers call this method an alternative, especially in cases where strength training is contraindicated after operations, injuries, etc.
Basically, we need to lift and lower the iron, bending and unbending the joint/s. Sit-stand, pull-release, lower-squeeze. This is the most effective way to create high mechanical tension for muscle growth.
And one more thing about mechanical stress.
Failure and near-failure training
If we simply take a random weight that is too small and bend/extend the joint, the mechanical stress will not be enough to cause a high level of effort.
Our muscles are not uniform, but consist of muscle fibers. They, in turn, are also different and can be roughly divided into low-threshold and high-threshold fibers. Low-threshold fibers, as the name suggests, have a low excitability threshold and are easily and quickly activated.
This is what muscle fibers look like. The darker ones are low-threshold.
In general, I mean that failure is an important thing, because it makes the entire muscle tense, but in fact, it is not a stimulus for growth, as many trainers and bloggers write/say. In fact, this is a mistake.
Non-failure training stimulates muscles in the same way as failure training. Only with a non-failure approach does the stimulus (and subsequently growth) occur not in all muscle fibers, but only in those that manage to get involved in the work, reacting to the appropriate level of tension.
Since we are interested in rapid and complete muscle growth, not just a small part of it, it is better to train close to failure. Recent studies show that intensity with 2-3 reps in reserve is as effective as complete failure.
Failure reps increase the potential for a hypertrophic response, but do not stimulate growth.
Mechanical tension is the only proven and, most importantly, controllable stimulus so far. Knowledge and understanding of mechanical action are easily transferred to practice. I recommend concentrating on this. However, without discussing the remaining two mechanisms, this post will not be complete. Therefore…
Metabolic stress
Metabolic stress is the accumulation of breakdown products in muscle, primarily lactate, inorganic phosphate, and hydrogen ions, caused by physical activity using the anaerobic system. And it is often ranked alongside mechanical stress in terms of the importance of the stimulus.
However, metabolic stress is more like a consequence of mechanical stress than an isolated phenomenon.
Metabolic stress is more common for multi-repetition workwhen the muscles are under prolonged tension. Working on 12-30 repetitions we will get much more metabolic stress than working in the range of 1-5 repetitions. This also raises the question of the influence of metabolic stress on the formation of a stimulus for muscle growth, since it is already well known that any rep range from 5 to 30 reps (to or close to failure) results in similar muscle growthIf metabolic stress had an effect on growth, we would probably grow a little better with high reps.
And yet, metabolic stress is inseparable from mechanical stress. By creating mechanical stress, metabolic stress also occurs, and it is not yet possible to study each mechanism in isolation.
Therefore, any methods of muscle stimulation that cause strong metabolic stress do not have a solid basis and should not be carried away by them, especially if you do not like it, it only brings unpleasant sensations. Such methods include high repetitions with the sole purpose of causing a burning sensation in the muscles, partial amplitude, short rest series, blood flow restriction, supersets, drop sets, etc.
These tools can be used, but each of them has limited conditions of application, some have a pedagogical purpose, but all of them are not a training method by default. (not counting supersets).
Microtraumatism
Microtrauma used to be the dominant hypothesis for muscle growth with resistance training. Muscles get torn during training and then heal. Muscle research has changed that, but microtrauma is still considered a stimulant, just a bad one.
There is surprisingly much evidence for this. But from all of them, one conclusion follows: although microtrauma is a cause for muscle growth, its contribution to muscle growth is small and tends to zero with systematic gains in the long term. What's worse, sometimes it even sabotages your progress.
One of the symptoms of microtrauma is a decrease in the ability to reproduce force. Excessive muscle damage will reduce the productivity of subsequent training.
As Brett Schoenfeld writes in in his book:
“Research remains mixed on whether microtrauma can enhance muscular adaptations. Excessive damage certainly has a negative impact on muscle development. If microtrauma does mediate muscular adaptations, it remains to be seen to what extent these proposed mechanisms are synergistic and whether there is an optimal combination to maximize the hypertrophic response to resistance training.”
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