Physical activity affects the gut microbiome and the gut microbiome affects physical performance. The relationship is bidirectional.
Recent studies reveal that while high-intensity, long-duration exercise can cause a leaky gut and dysbiosis (disturbance of the gut bacteria) while low-to-moderate exercise maintains that balance.
So should all athletes consume probiotics?
The effects of physical activity on the microbiome vary significantly with the type of exercise, such as endurance training, resistance training, and different sports.
Research demonstrates that athletes across sports like rugby, long distance cycling & running, triathlons, badminton, often develop distinct microbiome profiles after exercise, marked by increased good microbial species.
A healthy gut microbiome can contribute to maintaining physical strength and functionality as we age. A compromised gut barrier can lead to joint inflammation, adversely affecting movement and physical performance.
Research is exploring the gut-joint axis & it’s relation to arthritis.
Researched Benefits
Athletes taking certain strains have experienced increased VO2 max, better immunity & delivery/utilisation of nutrients, reduced inflammation and soreness during training, improved performance and recovery & reductions in body fat.
Mechanisms:
- Microbiome and physical performance:
Moderate aerobic exercise boosts the production of immunoglobulin A in the gastrointestinal tract, enhancing the gut microbiota’s ability to prevent intestinal pathogen colonisation.
Regular moderate-intensity exercise, particularly resistance training, reduces circulating levels of lipopolysaccharides (LPS) and decreases the expression of Toll-like receptors. This reduction is associated with decreased inflammation and improved gut barrier function.
Exercise has been shown in studies to have an essential role in controlling bile acid pools, which promotes the health of the host gut microbiota. The secondary bile acids generated by the microbiota are detected by the tissues via the activation of the Farnesoid X receptor (FXR) and the G-protein-coupled bile acid receptor, which play critical roles in energy metabolism.
The gut microbiota can efficiently control the body’s metabolic capacity and muscle growth by inhibiting FXR.
Hydrogen sulphide is another messenger generated by gut bacteria that controls the metabolism of intestinal immune cells. Hydrogen sulphide may be a possible target for improving muscle growth and function.
A strong correlation exists between short-chain fatty acids (SCFAs), produced by gut bacteria, and muscular strength. SCFAs can directly activate AMPK in muscles. This activation plays an important role in muscle development and growth.
Mice treated with antibiotics demonstrated reduced muscle hypertrophy indicating that destroying good bacteria inhibit muscle growth.
One notable SCFA, butyrate, promotes the release of glucagon-like peptide-1 (GLP-1) suggesting that it could play a role in reducing muscle breakdown. It specifically supports aerobic metabolism in skeletal muscles by boosting mitochondrial function.
The gut microbiota also plays a significant role in protein metabolism. In the small intestine, certain bacteria such as Clostridium, Bacillus, Streptococcus, and Proteobacteria can enhance the gut’s ability to absorb amino acids. For instance, Bacillus coagulans can increase amino acid levels in the serum following milk protein consumption.
The gut microbiome can affect the production of hormones such as insulin and androgens, which are essential for protein synthesis and muscle development. For instance, the bacterium Bacteroides, known for its pro-inflammatory properties, promotes insulin resistance by enhancing adipose tissue. Elevated levels are commonly observed in individuals with Polycystic Ovary Syndrome.
Recent research has emphasised the gut–brain–muscle axis, suggests that the gut bacteria can influence mood and stress by interacting with the central nervous system through processes like increased dopamine signalling, which in turn encourages exercise behaviours.
- Exercise impacts the microbiome:
Stress initiated by exercise can stimulate the hypothalamic–pituitary–adrenal axis, resulting in the production of cortisol and noradrenaline, both of which affect the gut microbiota, encouraging the growth of bad bacteria.
The production of corticotropin-releasing factor also alters gastrointestinal function, influencing inflammatory processes, colonic transit duration, mucosal secretory functions, barrier functions, and the growth of the intestinal tract bacteria.
Excessive physical activity can raise body temperature and cause extreme heat stress, negatively impacting the gastrointestinal microbiome. It reduces gut blood flow, resulting in relative ischemia and increased intestinal permeability, which may allow bacteria to migrate from the intestines and cause gastrointestinal issues.
Conclusion:
Research does show a positive association between good gut bacteria and physical performance.
Probiotics can be considered a part of an athlete’s stack. The type of strains, dosage, frequency and timing must be guided by a sports physician or qualified dietitian.
~ Shwetha Bhatia, Registered Dietitian (Indian Dietetic Association)
Reference:
Physical Exercise and the Gut Microbiome: A Bidirectional Relationship Influencing Health and Performance
Nutrients 2024, 16(21), 3663