The effects of 6 wk of resistance training on the gut microbiome and cardiometabolic health in young adults with overweight and obesity.

Obesity is a known risk factor for the development of insulin resistance and other cardiometabolic disorders. Recently, the gut microbiome has been associated with obesity and subsequent health complications. Exercise has been regularly utilized as a therapeutic intervention to treat obesity and its associated comorbidities. This study examined the effects of a 6-wk resistance training exercise program (RT) on the diversity, composition, and metabolic pathways of the gut microbiome. Sedentary young adults (age 18-35 yr) with overweight and obesity (BMI 25-45 kg/m2) were recruited to participate in this randomized controlled trial. Participants were randomized to RT (n = 16), a 6-wk resistance training program (3 days/wk), or control (CT) (n = 16), a nonexercising control. Main outcomes of the study included gut microbiome measures (taxa abundances, diversity, and predicted function) and cardiometabolic outcomes [blood pressure (BP) and glucoregulation]. Increased abundances of Roseburia, a short-chain fatty acid (SCFA) producer were observed over 6 wk (W6) with RT compared with CT (group × week, P < 0.05, q < 0.25). RT also induced marginal alterations in predicted microbial metabolic and cell motility pathways compared with CT (group × week, P < 0.05, q < 0.25). However, RT did not significantly impact overall microbial diversity. Furthermore, RT resulted in higher quantitative insulin-sensitivity check index (QUICKI) and lower diastolic BP at W6 compared with CT [baseline (BL)-adjusted P < 0.05]. RT had mixed effects on the gut microbiome. Although RT increased abundances of Roseburia and induced minor changes in microbial pathways, it is important to consider these changes in the context of the overall stability observed in the microbiome composition.NEW & NOTEWORTHY Resistance training induces mixed changes in the gut microbiome, including an increase in the abundances of the Roseburia genus and minor alterations in microbial pathways. However, it is vital to interpret these changes in light of the broader context, where we observe stability in the overall microbiome composition. This stability may be attributed to the microbiome's resilience, demonstrating its capacity to withstand short-term physiological stressors.

A systematic review on the effects of exercise on gut microbial diversity, taxonomic composition, and microbial metabolites: identifying research gaps and future directions.

The gut microbiome, hosting a diverse microbial community, plays a pivotal role in metabolism, immunity, and digestion. While the potential of exercise to influence this microbiome has been increasingly recognized, findings remain incongruous. This systematic review examined the effects of exercise on the gut microbiome of human and animal models. Databases (i.e., PubMed, Cochrane Library, Scopus, and Web of Science) were searched up to June 2022. Thirty-two exercise studies, i.e., 19 human studies, and 13 animal studies with a minimum of two groups that discussed microbiome outcomes, such as diversity, taxonomic composition, or microbial metabolites, over the intervention period, were included in the systematic review (PROSPERO registration numbers for human review: CRD42023394223). Results indicated that over 50% of studies found no significant exercise effect on human microbial diversity. When evident, exercise often augmented the Shannon index, reflecting enhanced microbial richness and evenness, irrespective of disease status. Changes in beta-diversity metrics were also documented with exercise but without clear directionality. A larger percentage of animal studies demonstrated shifts in diversity compared to human studies, but without any distinct patterns, mainly due to the varied effects of predominantly aerobic exercise on diversity metrics. In terms of taxonomic composition, in humans, exercise usually led to a decrease in the Firmicutes/Bacteroidetes ratio, and consistent increases with Bacteroides and Roseburia genera. In animal models, Coprococcus, another short chain fatty acid (SCFA) producer, consistently rose with exercise. Generally, SCFA producers were found to increase with exercise in animal models. With regard to metabolites, SCFAs emerged as the most frequently measured metabolite. However, due to limited human and animal studies examining exercise effects on microbial-produced metabolites, including SCFAs, clear patterns did not emerge. The overall risk of bias was deemed neutral. In conclusion, this comprehensive systematic review underscores that exercise can potentially impact the gut microbiome with indications of changes in taxonomic composition. The significant variability in study designs and intervention protocols demands more standardized methodologies and robust statistical models. A nuanced understanding of the exercise-microbiome relationship could guide individualized exercise programs to optimize health. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=394223, identifier CRD42023394223.