How Your Microbiome and Resistance Training Link to Better Health
In recent years, the gut microbiome has emerged as a key player not only in digestion and immunity, but in whole-body health, including how muscles perform, recover, and adapt to training.
This growing area of research helps explain why some people struggle to build muscle, why training responses vary, and how resistance training itself may support long-term gut and metabolic health.
What is a microbiome and why is it important?
The microbiome refers to the community of microorganisms, mainly bacteria, that live on and inside the human body.
These microbes play a crucial role in protecting against pathogens, supporting immune function, helping digest food, and producing energy-related compounds.
The largest and most influential part of this ecosystem is the gut microbiome, which contains thousands of different bacterial strains. The gut microbiome begins developing early in life and performs many essential functions, including:
- Breaking down dietary fibres into useful metabolites
- Producing signalling molecules that influence inflammation and metabolism
- Supporting the gut lining as a physical barrier
- Helping synthesise certain vitamins
A healthy gut microbiome helps maintain balance throughout the body, including systems involved in exercise recovery and muscle health.
What’s the relationship between gut health and resistance training?
Resistance Training → Gut Health
Studies found that resistance training may help strengthen the gut barrier — the lining that separates the gut from the bloodstream.
The studies have shown that resistance training can reduce levels of zonulin, a protein involved in regulating how “tight” the junctions are between gut lining cells. Higher zonulin levels are associated with increased gut permeability (sometimes referred to as “leaky gut”), where unwanted particles may pass into the bloodstream and trigger inflammation.
After six weeks of combined resistance and endurance training, participants with type 2 diabetes showed lower zonulin levels, suggesting improved gut barrier integrity. In the same study, increases in mucin production were also observed. Mucin forms a protective mucus layer in the gut and helps keep the gut lining resilient and well defended.
Because gut bacteria help regulate mucin production, this suggests that resistance training may indirectly support a healthier gut environment by influencing which microbes thrive.
Strength training doesn’t just challenge muscles — it may also help reinforce the gut’s protective barrier.
Gut Health → Resistance Training
Emerging research also points to a link between gut bacteria and how well the body adapts to resistance training.
In one study, participants completed eight weeks of resistance training while researchers tracked changes in gut microbiome composition. Those who improved their strength the most (measured by squat performance) had different gut bacterial profiles compared to those with smaller strength gains.
This means certain bacteria might support better training adaptation and exposes the discussion of the gut muscle axis, the connection between gut health and function and muscle health and function.
The bacteria found in people who got stronger are known producers of short chain fatty acids (SCFA), particularly butyrate. SCFA have many benefits including:
- Improve muscle protein synthesis
- Improved mitochondrial function- this helps cells produce energy more efficiently
- Reduced chronic inflammation- inflammation slows muscle growth and recovery
- Improve gut barrier integrity- poor gut integrity is linked with inflammation and poor recovery
This supports the idea of a gut–muscle connection, where gut health and muscle adaptation influence one another rather than functioning as separate systems. A gut environment that supports beneficial bacteria may help the body adapt more efficiently to strength training.
Why does this matter for people trying to build muscle?
Muscle growth is not driven by training alone. It is shaped by recovery capacity, inflammation levels, energy production, and overall metabolic health - all of which are influenced by the gut.
People with a microbiome that supports SCFA production may experience better training adaptations, reduced inflammation, and improved recovery. While genetics, nutrition, sleep, and stress all play a role, gut health is also an important piece of the puzzle.
How to strengthen the gut–muscle connection
Train with resistance regularly.
Aim for at least two full-body resistance training sessions per week. Research shows gut-related benefits appear after 6–8 weeks, similar to how muscle adapts. Occasional workouts are less effective than steady, progressive training.
Combine strength with some aerobic movement.
Resistance training supports gut barrier health on its own, but studies suggest combining strength work with walking, cycling, or other aerobic exercise may lead to greater improvements in gut health, especially for metabolic and inflammatory markers.
Support recovery, not just training.
Your gut responds best when training is supported by adequate sleep, stress management, and recovery time. High stress and poor recovery can blunt both muscle and gut adaptations.
Remember that training works best alongside healthy habits.
Diet quality, fibre intake, and overall lifestyle influence how well your gut supports muscle recovery and adaptation. Strength training is most effective when it’s part of a broader, balanced routine.
A healthy gut doesn’t just protect digestion - it may help you train harder, recover faster, and build strength that supports long-term health.
Source:
Wagner, A., Kateřina Kapounková and Struhár, I. (2024). The relationship between the gut microbiome and resistance training: a rapid review. BMC Sports Science, Medicine and Rehabilitation, 16(1). doi:https://doi.org/10.1186/s13102-023-00791-4.
