Resistance training may strengthen your gut microbiome

While the most obvious results of lifting weights are often seen through physical changes like bulging biceps, recent research has unveiled a potential hidden benefit of strength training: an improvement in gut microbiome health.

Although there is no universal configuration of gut microbes associated with optimal health, specific microbial species are frequently linked to enhanced medical outcomes, including improved immune function and better aging. Key players in this dynamic include Faecalibacterium, Akkermansia, and Roseburia hominis. These microbes play a critical role in producing short-chain fatty acids such as butyrate, which aids in protecting the gut lining and reducing inflammation.

Diet is well-known as a significant factor influencing gut health, but exercise, particularly aerobic activities like cycling or running, has been shown to foster the growth of these beneficial microbes. This improvement may derive from enhanced blood flow, hormonal changes, or metabolic byproducts generated from physical activity, such as lactate. However, research concerning resistance training’s impact on the microbiome has yielded inconsistent results; while some studies reported substantial changes, others suggested negligible effects. “The existing literature is somewhat limited,” states Matthieu Clauss from the Norwegian School of Sport Sciences in Oslo.

To clarify these conflicting findings, Sven Nahnsen and his research team at the University of Tübingen engaged a substantial cohort of 150 sedentary adults and assigned them to an eight-week strength training program that incorporated various resistance exercises, including lateral pulls, seated rows, chest presses, and leg curls.

Unlike prior studies, this research utilized “smart” strength machines that automatically adjusted weight and range of motion based on individual performance while meticulously tracking progress. “Every single weight lifted and every repetition is logged digitally, providing us with highly precise data,” remarks Nahnsen.

Participants provided stool samples at the beginning, midpoint, and end of the training regimen, allowing researchers to analyze the genetic and metabolic profiles of prevalent gut microbes.

Despite the lack of overall changes in microbiome composition across the entire group, significant shifts were evident based on individual responses. Notably, participants who demonstrated marked strength gains exhibited higher proportions of Faecalibacterium and Roseburia hominis by the program’s conclusion. “These beneficial microbes were particularly pronounced in those who significantly enhanced their strength,” notes Nahnsen.

The reasons behind not all participants responding uniformly to the exercise program remain elusive. Initially, one might consider that effort level was the determining factor; however, compliance with the program was similar across both low and high performers. Remarkably, dietary changes resulting from the exercise might explain the differing microbiome alterations, though nutritional surveys indicated no significant differences in consumption patterns. “It’s still a factor we cannot entirely rule out,” Nahnsen acknowledges.

An intriguing hypothesis suggests that the microbial changes observed in high-performing individuals could have enhanced short-chain fatty acid production, potentially enabling their muscles to better adapt to the training over the eight-week period. Nahnsen emphasizes the need for further investigation into this possibility, considering it an area ripe for exploration.

This study serves as a robust foundation upon which to investigate the underlying mechanisms at play. “Our goal was to compile a ‘dictionary’ of microbes potentially influenced by resistance training, which will aid other researchers in exploring these pathways,” he explains. Striving to promote gut microbiome health in conjunction with exercise may improve the health benefits associated with physical training and enhance athletic performance.

While the study did not include a control group of non-exercising individuals, Clauss, who was not directly involved, expresses optimism regarding these findings. “These results reinforce the concept that exercise, irrespective of type, can positively influence gut health. Additionally, they introduce the notion that resistance training may result in specific, health-promoting shifts in the microbiome,” he comments. He concludes that incorporating both endurance and resistance training into health promotion strategies could be key to advancing microbiome health.