The increase or decrease in muscle mass depends on multiple factors. One of these variables, and one that is often neglected, is the time we spend completing a repetition in strength training. This is verified by a study published by the magazine Sports Medicine, that collects in detail the effects produced by the different intensities, volumes and rest intervals on muscle growth.
the perfect repetition
To achieve an increase in optimal muscle mass, we must focus, therefore, on each of the three parts having a move (being the optimal speed different in each of them). The duration of each one is expressed by means of digits: four is normal, although it can also be manifested in three digits, ignoring the last phase.
The eccentric phase
We tend to lengthen the eccentric phase of the exercise when we want to achieve greater muscle growth. “During this phase you work in the direction of gravity, so it is essential to master the technique, which should be slow and controlledand maintain tension in the muscles to avoid the temptation to drop the weight”, explains trainer Verónica Domingo.
The transition phase
It is called transition because it is the one that occurs in the middle of the other two movements: the eccentric and the concentric. In short, they are exercises in which we subject the muscle to tension but without making any movement. “This phase is not usually taken into account because it is not so important on a practical level. That is, it is not so significant for muscle development,” the expert points out.
The concentric phase
This phase is the one in which the muscle contracts, when we beat the load (goes against gravity). Here, the insertion points of the muscle are approximated. “It is important to make an explosive movement to recruit more muscle fibers, leading to greater activation at the muscular level (which is activated when working at maximum speed),” says the coach.
According to a review on this subject, similar responses can be produced in the increase of muscle mass when the duration of the exercise goes from 0.5 to 8 seconds. In addition, it has been seen that very slow repetitions, longer than 8 seconds, can be detrimental to hypertrophy (that is, muscle growth).
In this way, and in conclusion, we understand that exercises with a movement that is too slow or too fast are not the most effective for gaining muscle. Yes they will affect, on the contrary, other variants such as total repetitions that we are able to do.
The key will therefore be a combination of slower eccentric movements with faster concentric movements: “On a practical level, the most effective thing is to do a number of repetitions (ideally between 12 and 20 repetitions) with a sufficient load and reaching muscle failure.
That is, reaching the maximum of the muscular capacity, so that in a series of a certain exercise it is impossible to do one more repetition”. In addition, “remember, the most important thing is get the technique righttaking into account that the perfect technique is different for each individual depending on their anthropometric characteristics and other factors”, concludes the expert.
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