A study shows that bodybuilding and bodybuilding



image: A moderate training protocol reduced liver fat and made the organ more sensitive to insulin, even before bodyweight loss.
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Credit: Guilherme Peruca

Research conducted at the University of Campinas (UNICAMP) in the state of São Paulo, Brazil, shows that vigorous physical exercise such as strength training and strength training can reduce the fat accumulated in the liver and improve the control of the liver. blood sugar levels in obese and diabetic people within a short time, even before significant weight loss occurs.

In experiments with mice, researchers at UNICAMP’s Exercise Molecular Biology Laboratory (LaBMEx) found that two weeks of such exercise was sufficient to alter gene expression in liver tissue. so as to “burn” more stored lipids and aid in the treatment of non-alcoholic fatty liver disease. sickness. Cellular insulin signaling in tissues improved and hepatic glucose synthesis decreased.

The results of the study, supported by Ṣo Paulo Research Foundation РFAPESP, are published in the Journal of Endocrinology.

“Everyone knows that physical exercise helps control disease. Our research focuses on how and why this is so, on the mechanisms involved. Whether we can uncover a key protein that levels increase or decrease with training, we will have taken a step towards developing drugs that mimic some of the benefits of physical exercise, ”said Léandro Pereira de Moura, professor at the School of Applied Sciences of UNICAMP and principal investigator of the study.

Moura explained that excess fat in the liver causes local inflammation, which makes liver cells less sensitive to the action of insulin. This condition can progress to cirrhosis and eventually to liver failure.

“In obese people at cardiometabolic risk, reducing liver fat is vital to help control diabetes,” Moura said. “The liver should only produce glucose on an empty stomach, but if insulin signaling in tissues is impaired, the liver releases glucose into the bloodstream even after carbohydrate ingestion, when insulin levels are high, which increases the level of sugar in the blood. “

Muscle training for mice

To study the effect of strength training on the liver, an experiment involving three groups of mice was performed. The control group, which was fed a standard diet (4% fat), remained lean and sedentary. The second and third groups were fed a hyperlipidemic diet (35% fat) for 14 weeks, long enough for the animals to become obese and diabetic. The second group remained sedentary, while the third group was put on a protocol of moderate resistance training for 15 days after becoming obese and diabetic.

The exercise protocol was to climb a staircase with a weight attached to the tail. Each day, the mice climbed the stairs 20 times at 90 second intervals. According to Moura, the protocol was designed to mimic strength training in humans.

“Before starting the experiment, we performed tests to determine the maximum load that each animal could withstand. We used a weight corresponding to 70% of this limit in the workouts. Our group had previously show overtraining can contribute significantly to the development of non-alcoholic fatty liver disease. Excessively strenuous exercise can do more harm than good, ”said Moura.

The researchers opted for a short exercise protocol of just 15 days to demonstrate that the observed benefits were directly related to bodybuilding and not to the side effects of weight loss.

In fact, the researchers found that although the mice subjected to the exercise training were still obese at the end of the 15-day period, their fasting blood sugar levels were normal, while the mice in the sedentary obese group remained diabetic until the end of the 15-day period. at the end of the period. experience.

Analysis of liver tissue showed a 25-30% reduction in local fat in the group that performed the exercise protocol compared to the fat level in the sedentary obese group. The amount of pro-inflammatory protein was also reduced in the exercise group, yet the mice in this group still had around 150% more liver fat than the control group.


On an empty stomach, the liver is the primary organ responsible for maintaining adequate blood sugar levels. In diabetes, control of gluconeogenesis (endogenous glucose production) is absent due to insulin resistance, and the individual may become hyperglycemic.

To assess the effect of strength exercise on controlling hepatic gluconeogenesis, the researchers tested the animals for tolerance to pyruvate, the main substrate used by the liver to produce glucose.

“The test basically consisted of administering pyruvate to mice and measuring the amount of glucose produced by the liver,” Moura explained. “We found that trained mice produced less glucose than sedentary obese mice even though they received the same amount of substrate. This showed that the trained animal’s liver underwent metabolic changes that made it more sensitive to it. insulin.”

Next, the researchers studied the mechanism by which exercise reduced liver fat. To do this, the researchers analyzed the tissue expression of genes associated with lipogenesis (synthesis of fatty acids and triglycerides, contributing to fat accumulation) and lipolysis (degradation of lipids for use as a source of fat. energy by the body).

“We compared the obese sedentary mice with the mice exercised through gene and protein analyzes to assess the synthesis and oxidation of liver fat,” Moura said. “We observed a tendency for greater accumulation of fat in the liver in sedentary mice.”

He added that an important contribution of the study was its demonstration that strength exercise promoted beneficial alterations in tissues that were not directly influenced by skeletal muscle contractions.

“Our next step will be to find out how this communication between the muscles and the liver is processed. Our hypothesis is that a protein called clusterin may be involved,” he said.

If the exercise-induced increase in clusterin levels proves to be beneficial, Moura said, treatments with synthetic alternatives could be tested.


About the São Paulo Research Foundation (FAPESP)

The São Paulo Research Foundation (FAPESP) is a public institution whose mission is to support scientific research in all fields of knowledge by awarding scholarships, scholarships and grants to researchers linked to educational institutions and Research Institute of the State of São Paulo, Brazil. FAPESP is aware that the best research can only be done by working with the best researchers at the international level. Therefore, it has established partnerships with funding bodies, higher education institutions, private companies and research organizations from other countries known for the quality of their research and has encouraged scientists funded by its grants to further develop their international collaboration. You can find out more about FAPESP at http://www.fapesp.br/fr and visit the FAPESP press agency at http://www.agencia.fapesp.br/fr to keep abreast of the latest scientific advances, FAPESP helps achieve through its many programs, awards and research centers. You can also subscribe to the FAPESP press agency at http://agencia.fapesp.br/subscribe.


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