Exercise shapes our gut health, study finds

In a recent study published in the journal EBioMedicineteam of scientists investigated the relationship between physical activity levels and gut microbiota using accelerometer-based assessments of sedentary, moderate, and vigorous physical activity levels.

Study: Accelerometer-based physical activity is associated with gut microbiota in 8416 individuals in SCAPIS. Image credit: Jeanne Mendel / Shutterstock

Background

A growing body of evidence shows that optimal levels of physical activity reduce the risk of type 2 diabetes, cardiovascular disease and mental health conditions such as depression. In addition, sedentary habits involving activities that involve prolonged periods of sitting or lying down are known to increase the risk of cardiovascular mortality and type 2 diabetes, and these risks can be reduced by high-intensity exercise. Recent studies have also shown that the positive health effects of exercise may be mediated through changes in the gut microbiome.

Considerable research also shows that the gut microbiome plays an important role in the development of various diseases and mental health problems. In addition to interactions with the host in the gastrointestinal tract, the gut microbiota is also believed to produce neurotransmitters that can influence the immune system, central nervous system and brain homeostasis through various neural pathways and the microbiota-gut-brain axis. Physical activity and the resulting changes in blood circulation, enterohepatic movement of bile acids, intestinal permeability and intestinal immunity can affect the gut microbiota.

About the research

In the current study, researchers used data from the Swedish Cardiopulmonary Bioimaging Study to determine whether sedentary, moderate, and vigorous physical activity patterns were associated with changes in the gut microbiome. Although a number of previous studies have examined this relationship, most have used self-reported levels of physical activity, which is subject to bias. Furthermore, the authors believe that the taxonomic resolution of gut microbes was limited in these studies.

This study used data from a hip-worn accelerometer to obtain a more reliable and accurate measure of physical activity levels. In addition, the use of shotgun deep metagenomics was thought to provide high-resolution taxonomic information on gut microbial communities.

Study participants had to answer a detailed questionnaire about their health and medical history, diet and lifestyle habits. They underwent a series of physical and clinical examinations such as lung, coronary artery and abdominal computed tomography (CT). Participants also provided fecal samples that were used for gut microbiome analysis. An accelerometer was worn on the hip by all participants for one week, at all times except while participating in water-based activities or sleeping.

Accelerometer data were converted to counts per minute, which were then used to define sedentary, low, moderate, and vigorous levels of physical activity according to cutoffs validated by previous studies. Deoxyribonucleic acid (DNA) extraction was performed for all faecal samples and the extracted DNA was then used to identify metagenomic species.

Various indices of species diversity, such as Simpson’s inverse index, Shannon’s diversity index and species richness, were calculated to determine alpha diversity. Additionally, differences in microbial composition between samples were determined by calculating beta diversity.

Results

The results showed that the relationship between sedentary habits or very low levels of physical activity and the abundance of different types of gut microbes was inverse to the relationship between moderate or intense levels of physical activity and the abundance of gut microbes.

The abundance of E. coli was found to be highly associated with levels of sedentary physical activity, while moderate levels of physical activity were associated with lower abundance of E. coli. The abundance of butyrate-producing bacteria, such as those belonging to rose storm genus, i Faecalibacterium prausnitzii was high in individuals with moderate and vigorous levels of physical activity.

In addition, differences in species abundance were observed, such as Prevotella coating, between individuals with moderate levels of physical activity and those in the vigorous physical activity group. The abundance of P. coverage was higher in association with moderate levels of exercise, but vigorous exercise showed no association with P. coverage abundance.

The functional potential of the gut microbiome has also been found to differ in relation to different levels of physical activity. Moderate levels of physical activity were found to be associated with higher synthesis of acetate and butyrate. Vigorous exercise was found to be associated with higher propionate synthesis, and sedentary activity levels were associated with a lower carbohydrate-degrading capacity of the gut microbiota.

Conclusions

Overall, the findings show that physical activity levels are strongly associated with the abundance of specific gut microbes. Furthermore, the diversity and abundance of the gut microbiota and subsequently its functional potential change with different levels of physical activity. Sedentary habits and higher levels of physical activity show opposite associations with gut microbiome abundance and diversity.