Attention to weight or repetition has the same effect on muscles – 06/07/2023 – Equilibrium

A study carried out at Unicamp (State University of Campinas) found that doing resistance exercises (bodybuilding) with a heavier load or doing a greater number of repetitions promote the same gain in muscle mass in the same period. Another finding of the research is that the body’s metabolic response after both types of training is also similar, that is, any model that the person chooses will have a similar result. The results were published in the scientific journal Metabolites.

The study was conducted with 18 volunteers who were followed by the researchers for eight weeks with different training protocols for the lower limbs: leg-press and leg extension. Some of the volunteers did the exercises with a higher load (up to 80% of the maximum weight the person could lift) and a lower number of repetitions (from 8 to 12, until reaching failure, when the muscle no longer responds) and another group did series with less load (up to 30% of the maximum weight), but with more repetitions (from 30 to 40 times, until exhaustion).

According to Professor Renato Barroso, from the Faculty of Physical Education at Unicamp and supervisor of the study, the training took place twice a week, for about 30 minutes. The volume of muscle mass was measured in the first and last exercise session by means of an ultrasound in the anterior part of the thigh. Muscle activation was assessed using a test called electromyography, with electrodes that monitor the electrical activity of the muscles.

“Resistance, strength training is recognized to promote muscle hypertrophy, but it is not entirely clear whether the most efficient way to gain mass is to value the weight of the load or the number of repetitions. With our results, we came to the conclusion that the two workouts reached very similar results, with the same hypertrophy”, says Professor Barroso. The average gain in muscle mass at the end of the evaluation period was 6% in both evaluated groups.

But as the main objective was to know if there were different metabolic alterations in the organism depending on the type of training, the researchers needed to evaluate the metabolic stress – which are the substances released in the bloodstream after physical exertion. For this, they collected blood samples from the participants in three moments: fasting (before training); five minutes after practice and one hour after exercises.

This action – called metabolomics analysis – detected the variation of 50 metabolites (products of metabolism) in the blood when the muscles were activated in both workouts, with little variation between them. Only six of them were more altered and the researchers went to assess their relationship with hypertrophy.

“The aim of the research was to understand whether there was a difference in metabolic response [diferenças na forma como o músculo produz energia] according to the training performed. What was expected was to find different energy pathways associated with hypertrophy, but that is not what we found. We then conclude that there is no difference either in terms of muscle mass gain or metabolic stress in these two types of training. The important thing is to train, “he said.

According to Barroso, an important issue to be taken into account is that when the person trains with a very light load, the tendency is for him to interrupt the performance of the series faster, before reaching failure. “She could even do more repetitions in the series, but she stops the exercise when she starts to feel tired. The person who trains with a heavier load usually gets closer to failure”, he indicates.