By Jana Bounds
It shouldn’t be a surprise that scientific research is advancing the belief that the human body functions largely like a machine, with many mechanisms dependent on and influenced by each other.
The human microbiome is often regarded as a second brain. It’s a collection of microorganisms that inhabit the human body, particularly the gut. These microorganisms are essential to human health, influencing everything from digestion to immune function.
Recent research suggests that exercise significantly impacts the microbiome, with potential implications for overall health and fitness.
Exercise and the Gut Microbiome
A 2018 study found that exercise altered the gut microbiota composition and function in both lean and obese humans. Specifically, the researchers found that exercise increased the abundance of beneficial bacteria, including Akkermansia muciniphila and Faecalibacterium prausnitzii, while decreasing the abundance of potentially harmful bacteria such as Escherichia coli.
Other studies have found similar results, including a study that investigated the gut microbiota composition in male rat models under different exercise training regimens. The researchers found that the exercise training regimens led to changes in the gut microbiota, with some exercise protocols leading to increases in beneficial bacteria such as Lactobacillus and Bifidobacterium.
Not only can exercise alter the composition of the gut microbiome, it may also affect the function of the microbiome itself. Findings from a 2016 study published in the journal Microbiome found that cardiorespiratory fitness was a predictor of intestinal microbial diversity and distinct metagenomic functions.
The researchers discovered that individuals with higher levels of cardiorespiratory fitness had greater microbial diversity and functional pathways associated with amino acid and energy metabolism, as well as decreased inflammation.
This review article from Frontiers, created by experts from France and Norway, points out that it may actually be a symbiotic relationship between the two: fitness influences the gut and the gut influences fitness levels.
While the exact mechanisms at play that allow exercise to impact the microbiome are not fully understood, there are several possibilities:
Type and Timing of Exercise
Scientists believe there may be ways to kick-start the gut microbiome. One Canadian study found that high-intensity interval training (HIIT) may be more effective than moderate-intensity continuous training (MICT) in altering the gut microbiome. The authors suggested that the greater metabolic stress induced by HIIT may lead to greater changes in the microbiome compared to MICT.
However, another study found that even women who did at least three hours of light exercise like brisk walking per week increased levels of Faecalibacterium prausnitziii, Roseburia hominis, and Akkermansia mucipiphila, in contrast to sedentary individuals. Akkermansia muciniphila is associated with lean body mass index (BMI) and better metabolic health, and F prausitzii and R. hominis reduces inflammation, which means that changes to the microbiome should influence overall health.
Implications for Health and Fitness
The connection between exercise and the microbiome has important implications for overall health and fitness. In fact, studies have suggested that exercise-induced changes in the microbiome may be associated with improvements in:
These findings suggest that these exercise-induced changes may contribute to the overall health benefits of regular physical activity.
In addition, the connection between exercise and the microbiome may also impact athletic performance. For example, a 2019 study published in the International Journal of Sport Nutrition and Exercise Metabolism found that supplementation with a probiotic containing Lactobacillus rhamnosus during a 12-week resistance training program led to greater improvements in muscle strength and power compared to a placebo. The authors suggested that the probiotic may have influenced the gut microbiome, leading to improved nutrient absorption and reduced inflammation.
Overall, the emerging research on the connection between exercise and the microbiome highlights the complex interplay between physical activity and human health. While much more research is needed to fully understand the mechanisms underlying these effects, the findings suggest that regular exercise may have important implications for the gut microbiome and overall health.
The Reverse is Also True: Exercise is Great for the Gut
But many studies have shown that the combination of exercise and diet can boost Faecalibacterium prausnitzii numbers and the production of butyrate in active women, often with improved gut function, according to BBC reporting.
"Some, but not all, studies have shown exercise to increase Faecalibacterium," Jeffrey Woods, a professor of kinesiology and community health at the University of Illinois at Urbana-Champaign told BBC. People with low levels of this type of bacteria appear to be more at risk of suffering inflammatory bowel disease, obesity, and depression, he added.
Woods and his colleagues explored how aerobic exercise would alter the gut microbes of previously sedentary people with different body mass indexes (BMIs). For the study, they asked participants to perform three moderate-to-vigorous intensity aerobic exercise regimens per week, either by running or cycling.
Stool and blood samples were collected consistently during the study, with three-day dietary controls enforced to make sure their diet remained consistent before each collection, to limit the changes caused by diet on gut microbes.
The study showed that “butyrate producers” increased with exercise training “irrespective of body mass index,” according to BBC.
These changes in the microbe community showed an uptick in short-chain fatty acids like butyrate in stool samples of lean participants.
“Interestingly, when those taking part in the study returned to their sedentary lifestyle over the following six weeks, the researchers found the participant's gut microbes returned to their initial state,” according to BBC. “It suggests that while exercise can improve the health of the microbial community in our guts, these changes are both transient and reversible.”
To summarize the complex science behind this issue: what you eat feeds your gut, which helps prompt you to exercise and your exercise alters your microbiome.
The human microbiome is a complex ecosystem that plays an important role in health. Recent research has suggested that exercise can have a significant impact on the composition and function of the gut microbiome, potentially contributing to the overall health benefits of regular physical activity.
The exact mechanisms underlying these effects are not fully understood, but may include changes in gut motility, immune function, and the production of short-chain fatty acids.
Overall, the emerging research on the connection between exercise and the microbiome highlights the importance of regular physical activity, particularly for maintaining a healthy gut microbiome and promoting overall health and fitness.
As we continue to learn more about the complex interplay between exercise and the microbiome, it is clear that regular exercise should be an important component of any healthy lifestyle.
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