Muscles produce a protein that promotes recovery after exertion and increases exercise capacity, according to research from the University of Hong Kong that has analyzed how muscle fibers are restored after intense physical activity.
A drug or nutritional supplement that acts like this protein, called BDNF, could help frail people gain muscle strength, people who tire quickly do more physical activity, and people who practice sports recover faster from efforts, the researchers say. authors of the research. There are already analogues of the BDNF protein in the development phase, although so far none have been approved.
Physical activity “causes metabolic stress” in the muscles, the researchers write in the journal Science Signaling, where this week they present their results. This stress leads to the accumulation of reactive oxygen species (such as free radicals) and the depletion of energy reserves, made up of lipids and glycogen.
Research has shown that physical activity also involves the production of BDNF in the muscles and that this protein is key in recovery after effort. Specifically, high levels of BDNF promote rapid recovery and make muscles more resistant to effort.
Although the research was carried out in mice, “we believe that BDNF has the same important function in the muscles of mice and humans,” biochemist Chi Bun Chan, director of the research, told La Vanguardia. “The structure of BDNF and its intracellular action is very similar between mice and humans,” notes Chan. Furthermore, “BDNF also increases after exercise in humans, which is the same thing we have seen in mice.”
Researchers have found that, in mice whose muscle cells cannot produce BDNF, the muscles’ ability to recover after exertion is impaired. And that animals do not increase their resistance capacity even if they exercise.
But if animals are given a BDNF analogue as a nutritional supplement, “increases in the distance they run, the time they spend running, the maximum speed at which they run, and the ability to hang” are recorded. They report in Science Signaling. This increased physical activity occurs without increases in muscle mass or strength, suggesting that BDNF increases muscle resistance to effort.
BDNF triggers a cascade of biochemical reactions in the muscles, researchers have observed. Specifically, they have shown that BDNF activates another protein called PPAR-delta, and that this in turn activates multiple genes that modify the muscle and increase its ability to exercise.
The University of Hong Kong’s experiments on the relationship between BDNF protein and physical activity have been carried out only with female mice, so it is unknown to what extent the results are valid in males.
Until now, the BDNF protein had been studied mainly for its action in the brain, where it is essential for the growth and functioning of neurons, and for cognitive functions such as memory. BDNF deficiency has been associated with Alzheimer’s, depression and schizophrenia, which has fueled interest in developing therapies that enhance this protein.
The BDNF analog used in the University of Hong Kong experiments is a flavonoid found in some plants called 7,8-dihydroxyflavone (or 7,8-DHF).
According to Chi Bun Chan, this analogue or a similar compound “could be used to improve the exercise capacity of people for whom physical activity is recommended, such as obese people.” The director of the research warns that “it is not a substitute for exercise, but rather an aid to leading a healthy life.”
On the other hand, “older people have less BDNF, and low levels of BDNF have been associated with greater frailty,” adds Chan. “Our results could partly explain why the muscles of older people atrophy. “We think that using BDNF or a similar substance as medicine could help improve muscle strength in older people.”
In people who practice sports, concludes the director of the research, “taking a BDNF analog could reduce the time needed to recover after each activity.” In the study, “we have not observed any side effects on the health of mice that have taken 7,8-DHF continuously for more than six months.”