Healthy gut microbiome essential for post-exercise muscle growth, study finds

27 Sep 2021 --- A healthy gut microbiome is necessary for skeletal muscles to fully grow after exercise, according to a study from the University of Kentucky, US. The study findings suggest the gut microbiome makes substances that help skeletal muscles to become larger after exercising.

The study further contributes to the growing body of evidence showing a connection between the gut microbiome and skeletal muscles.

“If we can identify the substances that gut bacteria are making to help muscles grow after exercise, we might be able to use some of those substances to promote the growth of muscles in people suffering from the loss of muscle as typically seen with aging or cancer,” explains Taylor Valentino, first study author.

From an athletic standpoint, world-class runners were found to have more of a particular type of bacteria that provided an additional source of energy, which was thought to help them run faster.

“Thus, the gut microbiome makes substances that appear to be important for skeletal muscles to fully adapt to exercise as well as help improve athletic performance,” says John McCarthy, senior study author.The microbiome may promote muscle growth in muscle loss conditions such as aging and cancer.

The study found that the muscles of mice without an intact microbiome did not grow as much as the muscles of healthy mice, even though both groups of mice ran the same amount over the nine weeks of wheel running.

The microbiome and skeletal muscles
Previous studies suggest the gut microbiome may be necessary for the health of skeletal muscles. Therefore the researchers wanted to determine if a healthy gut microbiome is essential for skeletal muscle to adapt to exercise.

“We are currently trying to determine how exercise changes the composition and function of the gut microbiome. This investigation, along with other studies in bacteria, will allow us to identify the substances made by the gut microbiome that help the skeletal muscle to grow larger in response to exercise,” adds McCarthy.

To study this further, the researchers let mice voluntarily exercise on running wheels every day for nine weeks, with some mice administered antibiotics through their drinking water. The antibiotic treatment killed the bacteria of the gut microbiome.

They then compared healthy mice’s muscles to those without an intact microbiome to see if the muscles adapted differently to wheel running.

Study limitations
Although the researchers used a relatively low dose of antibiotics compared to previous studies, a limitation of the study is that the researchers do not know if the antibiotics might have directly affected the ability of the skeletal muscle to adapt to exercise.The researchers found that an in-tact microbiome was necessary in mice for muscles to grow following exercise.

The initial research was conducted using only female mice. Therefore researchers do not know if the findings will be the same in male mice. Finally, as with all animal studies, it is unclear whether or not the results will translate into humans.

Industry players have shown interest in the potential of probiotics and vitamins for muscle health. In March, Hum Nutrition unveiled Core Strength, a protein powder that includes a blend of flaxseeds and probiotics to help build lean muscle.

Meanwhile, researchers from the UK found that vitamin C holds potential in muscle maintenance for elderly populations. A separate study supported by TSI found that muscle loss in the elderly was minimized through a combination of beta-hydroxy beta-methyl butyrate (HMB) and vitamin D.

Edited by Nicole Kerr