Imagine your muscles as the engine of a high-performance sports car. You might assume premium fuel (quality nutrition) and regular maintenance (exercise) are all it needs to keep running smoothly. But under the bonnet is a complex network of connections influencing every aspect of performance – this is your gut microbiome.
Your gut microbiome is a bustling community of bacteria living in your gastrointestinal tract and they are doing much more than digesting your breakfast. It’s now well known that your gut health affects digestion, immunity, and even your mental health, but recent research is pointing towards a role that is of particular interest to athletes. By playing an active role in muscle growth, strength, endurance, and recovery, your gut health is able to influence athletic performance [1] [2]. If you’re struggling with performance plateaus, fatigue, or slower than expected muscle development despite a solid training routine, it may be your gut health that is holding you back.
In this blog post, we’ll explore the bidirectional interaction between the gut microbiome and skeletal muscle, specifically:
The science behind the gut-muscle axis and why it matters for recreational athletes.
How gut health influences muscle protein synthesis, energy metabolism, and inflammation.
Why this relationship becomes even more important with age to prevent sarcopenia (age-related muscle loss) and promote longevity.
Practical strategies to support gut health for better muscle development and athletic performance.
The Gut-Muscle Axis: Connecting Gut Health and Muscle Development
This relationship is known as the gut-muscle axis - a complex communication network between your gut microbiota and skeletal muscle, which means your gut health can impact everything from energy levels and inflammation to muscle protein synthesis [2].
This isn’t just relevant for elite athletes chasing marginal gains. It’s useful for recreational athletes, particularly as you get older and maintaining muscle mass, preventing sarcopenia, and staying active into old age becomes more important.
How Does Your Gut Health Influence Muscle Development?
1. Regulation of Immune Function and Inflammation
Inflammation is a silent enemy of muscle growth and recovery. Your gut microbiota plays a central role in regulating systemic inflammation and immune responses. However, when your gut bacteria are out of balance (dysbiosis), it can lead to increased intestinal permeability (commonly known as “leaky gut”), allowing harmful substances to enter your bloodstream and cause chronic inflammation [3].
Not only is chronic low-grade inflammation a contributing factor to many chronic diseases, it also directly contributes to muscle breakdown, fatigue, and anabolic resistance. Anabolic resistance refers to the reduced ability of muscle to synthesise protein in response to stimuli like exercise or protein intake, making it harder to build or maintain muscle mass [4] [5]. This is especially concerning for older adults, as anabolic resistance is a key driver of sarcopenia. If you have ever witnessed an elderly family member lose mobility after a stay in hospital, you will understand how important this is.
In contrast, maintaining a healthy gut microbiome may:
Improve the integrity of your gut barrier, preventing inflammatory substances from entering your bloodstream.
Promote the production of anti-inflammatory cytokines, reducing muscle-damaging inflammation.
Support the immune system’s ability to fight off illness, keeping you healthy and active [6] [7].
Fun Fact: Short-Chain Fatty Acids (SCFAs)
Your gut bacteria ferment dietary fibre to produce Short-Chain Fatty Acids (SCFAs) such as acetate, propionate, and butyrate. These SCFAs have potent anti-inflammatory properties, helping to maintain muscle function and support healthy ageing [8].
2. Nutrient Absorption and Metabolism
I’m sure it comes as no surprise that your gut is responsible for absorbing the dietary vitamins, minerals, and macronutrients needed for muscle growth and performance. But actually it goes way beyond that:
The SCFAs and other bioactive compounds that your gut bacteria produce are able to influence glucose metabolism and energy balance.
Your gut bacteria synthesize essential nutrients like vitamin K and certain B vitamins, which are crucial for energy production and muscle health [8] [9].
What does that mean for athletic performance? By supporting nutrient absorption, production and energy metabolism, a balanced gut microbiome improves endurance, supports recovery, and can improve overall athletic performance. It also reduces the likelihood of energy crashes and fatigue mid-workout – something that recreational athletes juggling training with busy lifestyles will be grateful for.
3. Protein Synthesis and Anabolic Resistance
Protein synthesis is the cornerstone of muscle growth and recovery. But, as previously explained, ageing muscle becomes less responsive to stimuli like protein intake and exercise. This anabolic resistance is a primary cause of sarcopenia.
Here’s where the gut-muscle axis can play a vital role:
Some gut bacteria can increase amino acid availability by enhancing nutrient absorption.
A healthy gut reduces inflammation, which is known to interfere with muscle protein synthesis.
Improved gut health supports hormonal balance, including insulin sensitivity, which is crucial for muscle growth and repair [9].
This makes gut health especially important for older recreational athletes training to maintain muscle mass and strength. By minimising anabolic resistance through gut health, you can slow down the muscle loss associated with ageing.
The Impact of Exercise on Your Gut Microbiome
Regular moderate exercise is one of the best ways to support gut health by increasing microbial diversity and promoting the growth of beneficial bacteria [10]. However, you can overdo it. Overtraining - intense exercise without adequate recovery - can cause chronic oxidative stress and inflammation which disrupts the gut microbiome. This imbalanced gut microbiome (dysbiosis), can negatively impact muscle function, increasing the risk of injury and burnout [11] [12]. Finding the right balance between training intensity and recovery is crucial to support gut health and muscle adaptation.
Foods to Focus on to Improve Your Gut Health
Fibre: Feeding Your Microbiome
Dietary fibre is like rocket fuel for your gut bacteria. It’s their main food source, and when they’re well-fed, they produce SCFAs that maintain your gut lining, reduce inflammation and support muscle health[13].
Soluble Fibre is easily fermented by gut bacteria to produce SCFAs. Load up on oats, chia seeds, sweet potato, less ripe bananas, avocado, nuts and legumes [14].
Insoluble Fibre can be found in whole grains, nuts, seeds and vegetables. It enhances gut immunity and supports intestinal integrity [15].
Phytonutrients: Essential Plant Compounds
Phytonutrients are powerful plant compounds with antioxidant and anti-inflammatory properties that support overall health. They also help stimulate the growth of beneficial gut bacteria, promoting a balanced and healthy gut environment.
Different plant foods contain unique combinations of phytonutrients, and their colours often indicate the specific benefits they provide. To get the most out of phytonutrients and support a healthy gut, aim to include a variety of colourful plant foods in your diet each day. Think beyond just fruits and vegetables – nuts, seeds, herbs, and spices all contribute to your phytonutrient intake and improve gut health. [16].
Omega-3 Fatty Acids: Anti-Inflammatory Support
Omega-3s are powerful anti-inflammatory fats that do more than just support heart and brain health - they also play a role in gut health. By promoting the growth of anti-inflammatory bacteria, strengthening the intestinal barrier, and enhancing immune function, omega-3s help to maintain a balanced and resilient gut [17].
To boost your Omega-3 intake, focus on oily fish like salmon, mackerel, sardines, trout, and anchovies. For plant-based sources, chia seeds, flaxseeds, seaweed, and walnuts are excellent choices.
Prebiotic and Probiotic Gut Support
Prebiotics and probiotics work hand-in-hand to nourish beneficial gut bacteria and promote microbial diversity. Regularly including them in your diet will support your gut health.
Prebiotics are non-digestible food compounds that serve as food for beneficial bacteria. When fermented by gut bacteria, prebiotics lead to the production SCFAs [18]. Common prebiotic-rich foods include:
Vegetables and fruits like onions, garlic, leeks, asparagus, bananas, and artichokes.
Whole grains such as whole wheat, barley, and oats.
Legumes like beans, lentils, and chickpeas.
Nuts and seeds like almonds and flaxseeds.
Probiotics are live beneficial bacteria that help restore and maintain the balance of gut microorganisms by promoting microbial diversity and reducing the colonisation of harmful bacteria [18]. Common foods containing probiotics are:
Fermented Dairy Products such as Kefir and yogurt are rich in live cultures of Lactobacillus and Bifidobacterium strains.
Fermented Vegetables such as Sauerkraut, kimchi contain a variety of beneficial bacteria.
Fermented drinks like Kombucha is rich in probiotics and antioxidants.
Raw Vinegars such as Raw apple cider vinegar contains beneficial bacteria and acetic acid which promotes a healthy gut environment.
Fermented Soy Products like Miso and tempeh provide probiotics and are excellent sources of plant-based protein.
Conclusion
If you’re serious about muscle development and athletic performance, overlooking gut health would be a mistake. A healthy gut is a powerful driver of muscle growth and recovery, playing a role in muscle protein synthesis, reducing inflammation, improving energy metabolism, and combating anabolic resistance.
This connection is even more important as you age. For older recreational athletes, maintaining muscle mass, preventing sarcopenia, and staying active is all supported by a healthy gut microbiome.
By including more gut-friendly foods, you’re not only supporting better digestion, you’re also enhancing muscle growth, speeding up recovery, and boosting overall performance. Prioritise your gut health and the benefits will follow.
References
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