Feel like your fitness efforts aren’t giving you the results you desire? The answer may not be in lifting heavier – but, rather, in the tiny microorganisms that inhabit your gut. Today, you’re going to learn about how probiotics may have a bigger impact on your fitness than your training routine itself.

Probiotics and AbsWhen you think of the link between your gut and getting into shape, what is the first thing that comes to mind? If a six-pack and a washboard stomach is what pops into your thoughts, we encourage you to think just a little deeper than that…

Look past the muscles and outward appearance.

Because, deep down in your digestive tract is something that may have a far more powerful influence on your fitness level and gains than your strength and muscles alone. Something that, when given just a fraction of the time and effort you devote to training, could be the reason you see better results; sooner than expected.

Introducing Your Gut Bacteria to Your Fitness Routine

Your athletic performance takes an equally significant amount of mental and emotional preparedness as it does movement and muscle. But there are other body systems involved in the process of getting into shape that you may not yet have thought of.

One of those systems is the gut. Typically, you only think about your digestion and its influence on your workouts as the way in which nutrients enter your body, how foods gives you energy and how it allows your muscles to grow.

However, there is a whole different world within your digestive tract that can impact this seemingly simple process of food as an input and, strength and growth as an output.

It has to do with your gut bacteria.

Now, you may be under the impression that bacteria are bad news, as we often associated them with illness and disease. The truth is, not all of them are. In fact, those that live in your digestive tract may be far more valuable to your gains than a Gold’s Gym membership.

Good Gut Bacteria

They are known as good bacteria and these healthy, diverse colonies create a symbiotic relationship with your body, meaning they actually work in your favor.

These bacteria help with nutrient absorption, in maintaining the barrier of nutrient exchange between the food you eat and what gets transported through your blood into your tissues and, they even provide your body with nutrient release as they take part in the digestive process (1).

It’s not all good news, though. The trouble occurs when there is an invasion of harmful types of bacteria and microbes (2), which happens more often than we like to admit.

In our modern world, “bad bacteria” have many more opportunities to start fighting off the good because of a number of factors we’re exposed to every day. Anything from stress to medication (3), eating processed or refined foods (4) and even being exposed to environmental toxins can have a dramatic effect on your gut bacteria.

Good and Bad Gut Bacteria

In these imbalanced environments, bad bacteria flourish and begin to outweigh the good. This process leads to the failure of that once healthy, symbiotic relationship your body shared with the good bacteria – and, it forces nutrient absorption to change, gut barrier function to crack and bad bacteria to release harmful compounds as they now take part in the digestive process (5).

Allow it to continue, and you’ll soon develop symptoms of fatigue, weakness, emotional upset, infection and injuries; all of which put a serious dampener on your efforts to get fit and strong.

These consequences may sound drastic, but they’re only the tip of the iceberg.

Once you compromise the integrity of your intestinal barrier function, you may also lose out on absorption of the essential nutrients you need to keep your body working as it should and to harness the fuel you need for power and endurance. In fact, if your gut is in a poor state, you may not end up utilising all of those good foods and supplements you take in an effort to keep yourself healthy and strong.

…you may also lose out on absorption of the essential nutrients you need to keep your body working…

Add to that your continued efforts as you push harder and harder during your workouts and you can start to paint a dreadful picture of ill health, weakening body systems and the failure to reach your fitness goals time and time again.

You see, the more you push, the more at risk you are. It’s well known in the athletic community that fatigue, mood disturbances, lowered performance and upsets in digestion often plague athletes both when they’re training and taking part in competitions.

Probiotics can cure fatigue

This process occurs due to a stress response and, while this is a natural safety mechanism of the body to maintain balance and homeostasis, it does cause inflammation (6). You don’t have to be an elite athlete, or be training for a competition to suffer these effects; stress on the body and mind results from any physical training, and so you can expect your body to undergo the same response as you keep trying to reach those goals.

In fact, as demonstrated in research, high intensity exercise increases an athlete’s susceptibility to infections (7,8) – particularly in respiratory tract infections (9) – which indicates changes in the effectiveness of the immune system.

If you take into account the direct interaction that your immune system has with your gut bacteria (10) and the stress it puts on your body, you can understand why your focus on training your muscles may need to shift to include looking after your gut health.

That’s where probiotics come in.


What Does a Probiotic do to Your Body?

In 2001, the World Health Organisation provided the definition of probiotics as live microorganisms that, “when administered in adequate amounts, confer a health benefit on the host.” (11) The medical site WebMD indicates that they are “live bacteria or yeasts that are good for your health, especially your digestive system”.

When you take probiotics in supplement form, or obtain them via food containing their live cultures, they are able to form their own colonies within your digestive tract, or contribute to those you already have (12).

Interestingly, as athletes or fitness fanatics, taking probiotics may have an even greater impact on your health and fitness than training alone.

Probiotics and ProteinProbiotics can influence your lean body mass, strength, power and overall health indicators as a result of exercise, concludes a study published in the Journal of the International Society of Sports Nutrition. During the study, researchers measured the vertical jump power of their healthy, resistance-trained volunteers. They found that in the group who included probiotics into their supplement routine, along with a fast-releasing protein product like whey, had a trend towards an increase in power in their jump when compared to the group who didn’t (13).

Other studies have determined similar results. In the International Journal of Biochemistry & Cell Biology, researchers present evidence of something called the gut-muscle axis. This axis describes the superhighway of communication pathways that allows the processes taking place inside your gut to influence your muscles growth and performance (14).

In this particular piece of evidence, researchers looked at muscle wasting in the elderly as a result of disease, in order to determine the effect of therapeutic targets – like probiotics – and whether they can offer benefits towards maintaining muscle mass. The evidence clearly shows that gut bacteria has multiple levels of influence on the muscular system, where one of the most notable and possibly influential is that of the gut barrier function (14).

Typically, the gut barrier is tightly controlled and only certain substances and nutrients are allowed to pass through into the blood, where they are then dispersed to the parts of the body they are needed (15).

When there are lesser amounts of healthy gut bacterial species, the integrity of this barrier is compromised and, as is control over absorption and dissemination of the absorbed compounds.

As a result, harmful compounds pass through the gut barrier into the blood, the immune system responds as if it is being attacked, and widespread inflammation begins to occur. Regarding overall fitness, the harmful effects can be seen as muscle atrophy, muscle wasting and immune dysfunction (16).

While this dramatic process is more commonly associated with disease and inflammation, the inflammation caused by intensity and frequency of exercise may produce the same results to a lesser extent and slowly progress to more detrimental health effects.

So – let’s bring this all back to probiotics.

These friendly bacteria are already commonly used in clinical settings as a therapeutic target for inflammatory gut diseases, and there’s promise of their use and multiple benefits in many other diseases and conditions that have inflammation at their root cause.

While exercise is certainly not a disease, we now know that it is inflammatory and your body needs the ability to cope with that inflammation and counter it in order to appropriately achieve the oh-so-good benefits of being a fitness freak!

So, in order to make sure your body is suited to the task, we can use probiotics to enhance the benefits of exercise, as well.

Let’s get to chatting about the type of probiotics that might be best for maximizing your gains, without the pain!

What is the Best Probiotic to Use to get Leaner, Meaner and Stronger

Now that you understand more about why you should be using probiotics, let’s discuss the research behind which probiotics might actually be the most worthwhile to start supplementing. Here’s a list of the best studied probiotics for reaching your health and fitness goals:

  1. Lactobacillus rhamnosus GG – One of the most widely studies species of bacteria in relation to health is Lactobacillus rhamnosus GG, or LGG for short. LGG has shown to promote better digestion, enhance immune health, increase resistance to infection and reduce the growth of harmful bacteria – all of which have a significant influence on both intestinal health and athletic performance (17). LGG also acts as a potent antioxidant (18) to counteract tissue damage that occurs during exercise and promote repair (19).
  2. Lactobacillus paracasei – To further enhance antioxidant benefits, LGG can be combined with a probiotic called Lactobacillus paracasei. In conjunction, these two strains have demonstrated to produce significant increases in serum antioxidant levels, corresponding to reduced levels of exercise-induced free radical production in athletes (20), meaning even greater breakthroughs in reducing tissue damage and promoting muscular repair.
  3. Lactobacillus plantarum – Lactobacillus plantarum has demonstrated promising results in animal studies to date. Research has demonstrated that during a six-week period of rats performing a variety of regular exercise, those that supplemented with Lactobacillus plantarum developed more slow muscle fibers (associated with strength) than the control group which did not use the probiotic. The scientists conducting this study explained these results to present promising evidence that Lactobacillus plantarum may play a role in increasing muscle mass while improving energy and athletic performance (21).

What is the Best Probiotic on the Market?

NOW_Probiotics_AmazonWhen you are looking for a probiotic supplement that will suit your needs, a common pattern that is seen in healthier individuals is a greater level of bacterial diversity. Additionally, probiotics are typically needed in higher doses as much of the bacteria are destroyed in the harsh stomach environment before being able to proliferate. Aim for a probiotic with at least 7 strains and 5 million colony forming units (CFUs), which you’ll know from looking at the ingredients list. Great strains to combine the above probiotics with include Bifidobacterium and Streptococcus, along with additional strains of Lactobacillus (22).

Next, always check whether the bacteria are live or if they are freeze dried. If the product says it contains live bacteria, it should be kept in the refrigerator to preserve viability.

Lastly, it’s important to check whether the product you choose is free of unnecessary additives, as cheap, drug-store supplements often contain additional or hidden ingredients which you may be sensitive to or may even pose negative health effects. These unwanted additives include synthetic chemicals and colorants. Aim for probiotics that contain a casing with natural ingredients only, such as pure cellulose or gelatin.

If you want to double-up on your daily probiotic dose – or, if you simply want to go the all-natural route and obtain these bacterial benefits from foods, probiotics and healthy microorganisms can also be obtained by eating a variety of fermented foods including kefir, kombucha, sauerkraut, miso and natural yogurt. Although the dosage may not be as intensive as probiotic supplements, many experts still advocate for these foods to be included as a regular part of your daily diet.

Depending on your routine, you can go solely for supplements or natural foods – or, combine them both to maximize the bacterial benefits and experience more rapid change.


Whichever you choose, just remember that focusing on the gut is a huge part of your health and training routine. By focusing on these small microbes inside your gut, you can start to see big changes in becoming fitter, leaner and stronger.


  1.  Villena, J., and Kitazawa, H. (2014). Modulation of intestinal TLR4-inflammatory signaling pathways by probiotic microorganisms: lessons learned from Lactobacillus jensenii TL2937. Front. Immunol. 4:512.
  2.  Quigley, E. M. M. (2013). Gut bacteria in health and disease. Gastroenterol. Hepatol. 9, 560.
  3.  Nicholson, J. K., Holmes, E., Kinross, J., Burcelin, R., Gibson, G., Jia, W., et al. (2012). Host-gut microbiota metabolic interactions. Science 336, 1262–1267.
  4.  David, L. A., Maurice, C. F., Carmody, R. N., Gootenberg, D. B., Button, J. E., Wolfe, B. E., et al. (2014). Diet rapidly and reproducibly alters the human gut microbiome. Nature 505, 559–563.
  5.  Ou, J., DeLany, J. P., Zhang, M., Sharma, S., and O’Keefe, S. J. D. (2012). Association between low colonic short-chain fatty acids and high bile acids in high colon cancer risk populations. Nutr. Cancer 64, 34–40.
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  7.  Engebretsen L, Soligard T, Steffen K, Alonso JM, Aubry M, Budgett R, Dvorak J, Jegathesan M, Meeuwisse WH, Mountjoy M+3 more. 2013. Sport injuries and illnesses during the London Summer Olympic Games 2012. British Journal of Sports Medicine 47(7):407-414
  8.  Engebretsen L, Steffen K, Palmer-Green D, Aubry M, Grant ME, Meeuwisse W, Mountjoy M, Budgett R, Engebretsen L. 2015. Sport injuries and illnesses in the Sochi 2014 Olympic Winter Games. British Journal of Sports Medicine 49(7):441-447
  9.  Colbey, C., et al. 2018. Upper Respiratory Symptoms, Gut Health and Mucosal Immunity in Athletes. Sports Medicine. 48(1):665-77
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  12.  Tripathi, M., and Giri, S. 2014. Probiotic functional foods: Survival of probiotics during processing and storage. Journal of Functional Foods. 9:225-241.
  13. Georges, J., et al. 2014. The effects of probiotic supplementation on lean body mass, strength, and power, and health indicators in resistance trained males: a pilot study. Journal of the International Society of Sports Nutrition. 11(1):38.
  14.  Bindels, B and Delzenne, M. 2013. Muscle wasting: The gut microbiota as a new therapeutic target? The International Journal of Biochemistry & Cell Biology. 45(10):2186-2190.
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  16. Suzuki, T., et al., 2011. (IL-6) regulates claudin-2 expression and tight junction permeability in intestinal epithelium. Journal of Biological Chemistry, 286 (2011), pp. 31263-31271
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Published by Anita Tee

Anita Tee is a published nutritional scientist carrying a Master of Science in Personalized Nutrition and a Bachelor of Science focused in Genetic & Molecular Biology. She is the founder & CEO of www.factvsfitness.com and www.biolifecontent.com, two evidence-based websites devoted to research for improving health naturally. Find out more about Anita by following her on YouTube, Twitter, Instagram or Facebook.

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