Varied strength training doesn’t boost muscle growth

Varied strength training has a positive effect on developing strength, but not on muscle growth, a new study finds.

For years, the word around gyms has been that to put on muscle, you need to vary your training with regards to weight, repetitions, and exercises.

“…periodized strength training is conducive to the development of strength, but not muscle mass.”

But the new findings show that so-called “periodized strength-training”—where training is varied by increasing and decreasing variables such as the amount of weight lifted, as well as the number of repetitions—benefits strength development.

“The study establishes that periodized strength training is conducive to the development of strength, but not muscle mass. If one wants to get stronger, it is important to vary their training,” says Jesper Lundbye-Jensen, associate professor in the department of nutrition, exercise, and sports at the University of Copenhagen and last author of the paper in Sports Medicine.

The answer as to why periodized strength training can promote the development of strength, but not muscle mass, is likely found in our nervous system, the researchers say.

“As people become stronger from periodized workouts compared to non-periodized workouts, it is most likely due to the fact that strength training trains the nervous system as well, and thereby our ability to coordinate and activate muscles to a maximum,” Lundbye-Jensen says.

Increasing muscle mass through strength training requires working out until fatigue sets in and putting in a sufficient number of hours at the gym to do so, says first author Lukas Moesgaard.

“The research suggests that strength training particularly results in muscle growth when training muscles to exhaustion. And, as a rule of thumb, more exercise leads to more muscle growth,” he explains.

In the study, the researchers could also see that those who already train regularly achieved more progress in strength by varying the intensity of their weekly training and alternating between heavy- and light-lifting exercises.

The untrained, on the other hand, received the same benefit from training, regardless of whether the variation took place on a daily or weekly basis, or whether the training was adjusted linearly—ie, by increasing loads as an individual gains strength—over an extended period of time.

“All in all, the study demonstrates that variation in weight load and the number of repetitions in strength training can help if one is keen on getting stronger, and that the variation should probably occur more often when one is trained than if one is untrained. However, our results also demonstrate that varying loads and the number of repetitions doesn’t seem to affect the amount of muscle growth,” Moesgaard says.

The article is based on a scientific study known as a systematic review with meta-analysis, where researchers collect and review all relevant scientific literature in a given field.

sources: University of Copenhagen

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