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Immediate adaptations or responses to strength training

Whenever we begin to perform a strength training program, our body responds in different ways, including a series of physiological adaptations, some occur during a session and others occur over time. Today we are going to discuss in this article the immediate and chronic adaptations to strength training.

These adaptations occur as a result of a progressive overload in training, among the different adaptations we find changes at the neurological level, in the muscular, connective, skeletal tissue, even at the hormonal level. Strength training produces multiple benefits on our body, let's see it below.

Basic adaptations to strength training

As we have previously introduced, we must highlight two different types of adaptations in strength training, on the one hand we find the immediate adaptations, also known as exercise responses, are those changes that occur during a training session and shortly after these, and on the other hand the adaptations that occur in the long term, which are the chronic adaptations.

The responses to a training session give rise to a series of changes at the neuromuscular level and these immediate changes or adaptations are what cause long-term chronic adaptations such as increased muscle mass or strength gain.


The changes that occur or the responses in the different systems, neurological, muscular and endocrine, are the ones we see in the following table:

Table of immediate responses to strength training. NSCA Manual - Fundamentals of personal training.

Neurological changes

When we train strength, we are not only training our smooth muscles, but we also use skeletal muscles, without its activation we cannot perform any physical activity. When we activate the skeletal muscle, an action potential is generated and to measure the degree of involvement of a muscle in a specific exercise we use what is known as electromyography (we could see it in the article on the activation of the pectoral in the bench press performing lumbar arch and leg drive).

When performing a repetition of an exercise, there is an increase in the amplitude of electromyography. This increase in amplitude occurs in relation to the production of force that we perform, although it is also affected by other factors such as fatigue and the composition of muscle fibers.

To perform muscular strength, we have to take into account two factors: recruitment and activation frequency of motor units. Recruitment is the process by which we activate more motor units to perform an exercise, for example, when we have to lift a very heavy load on the bench press, the higher the load we use, the greater the recruitment of motor units will be necessary.

While the activation frequency is the control of the discharge frequency of the motor units, that is, the number of action potentials that we use in a given time. The faster the discharge, the greater the force we can produce in a specific survey.

To get an idea, when we perform a series of bench presses with 4 repetitions, in the first repetition we will be able to recruit a very high number of motor units, but as we perform repetitions, due to fatigue, our ability to gather motor units decreases and our body tries to regain that force by increasing the activation frequency as much as possible. Fast fibers are capable of recruiting a greater number of motor units, which is why strength athletes have a greater number of fast fibers compared to endurance athletes who have a greater number of slow fibers.

Muscle changes

In a training session logically there are muscle changes, so as we perform different series, our muscles get tired. Specifically when a muscle is fatigued, what happens internally is that metabolites accumulate and also deplete or waste energy. We talked about energy systems and commented that in a strength training mainly involved phosphogens and glycolysis.

When the metabolites accumulate, there is a decrease in our level of muscular pH, in addition to the fact that phosphocreatine (the first element we use to produce energy) is rapidly depleted during an intense and short exercise. For this reason it is important that we have full glycogen stores if our training is going to be force-oriented, because we need that glycogen to get energy and be able to lift loads, since phosphocreatine is depleted very quickly.

Hence the importance of maintaining a diet that provides us with the necessary nutrients and we should not only consume protein if we train strength, or discard or reduce carbohydrates a lot, because they are our source of energy and if we are not loaded with glycogen, surely we cannot train with high intensity during a long training session.

In training with generally anaerobic loads, the greatest energy is produced by phosphogens and glycolysis, or what is the same, the use of muscle glycogen that we have in our body. If we reduce our diet too much in terms of carbohydrates, surely we cannot apply a high volume of training at high intensity due to lack of energy.

Endocrine changes

Our hormones are transported through the blood and are produced in the endocrine glands. Many hormones have a direct effect on our muscle tissues, we have hormones that help regenerate tissue, such as testosterone, growth hormone (GH) and insulin, which we call anabolic hormones and other hormones that degrade tissue to maintain body homeostasis such as cortisol, which is a catabolic hormone.

When we do strength training, there are a number of changes in hormonal levels, for example, after training, testosterone and growth hormone levels usually increase. Said increase causes greater protein synthesis in the muscle Skeletal and help us generate muscle mass. If we repeat for several days the fact of training correctly, it will help us to generate more muscle mass.

The hormonal response is different depending on the type of training we follow, for example, in training with more volume and short periods of rest, there is a greater response at the endocrine level than in sessions of less volume and more rest, although this difference decreases if there is a high frequency of training.

In exercises that involve a greater number of muscle fibers, there is also a greater response at the hormonal level, that is, that multiarticular exercises such as bench press, squats, deadlifts, promote a more suitable hormonal environment for the increase in long-term muscle mass.

Video: Physiological adaptations in response to training (January 2020).

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