Your gut is home to over 100 trillion different microbes that play a synergistic role in your health and performance. The majority of your gut microbiota are made up of bacteria that reside in the colon, however viruses, fungi and protozoa also play key roles.(1) Scientists are still uncovering all the complexities of how these microbiota influence our health, although we do know they help to support vitamin production, the breakdown of fiber and communicate directly with your immune system.(2)
The question for athletes is… “can your gut microbiota impact your athletic performance?” New research suggests it can. Let’s take a quick look at seven potential areas of interest:
1) Leaky Gut
Intense training puts a tremendous stress on the gastro-intestinal system, leading to altered blood flow and local inflammatory changes.(3) This can compromise the integrity of your gut wall, leading to intestinal hyper-permeability (i.e. leaky gut) and thus increased inflammatory response and potential for immune disturbance. In short, intense training puts a stress on your digestive system and it comes at a cost.
Allergy is common in athletes who train in more extreme conditions, like the cold air at altitude (or during winter months) or the chlorine in the water of your local pool. If you have an allergic condition, you’re at much greater risk of upper respiratory tract infection (URTI).(4) Nothing derails performance quicker than a nasty cold or flu. Probiotics have been shown to reduce the incidence and severity of URTI in athletes.(4)
3) Lack of Energy
If you’re training intensely and not providing sufficient caloric intake to meet your daily energy demands, your recovery, performance and health will all suffer. This is referred to as “relative energy deficit” (REDS) in the scientific literature.(5) In this low energy state, changes in gut microbiota are commonly seen and could potentially be used as future biomarkers of increased “stress load” on the athlete.
4) Mental Stress
Persistent psychological stress has also been shown to significantly alter gut bacteria. This is commonly seen in patients with chronic fatigue or post-traumatic stress disorder.(6)For athletes, whether it’s the stress of a collegiate athlete balancing school and sport or an elite athlete preparing for competition, mental stress can trigger significant changes in the microbiota. These changes could potentially influence inflammatory response, immunity, blood glucose response to meals, etc. and thus impact your ability to recover and perform.
5) Inflammatory Response
In clinical practice, clients suffering from inflammatory conditions like rheumatoid arthritis (RA) or gout display a common dysfunction in the balance of “good” to “bad” gut bacteria.(7) This type of low-grade inflammation is also seen in osteoarthritis and rotator cuff tendon degeneration, which means getting back to the root cause – diet, movement, lifestyle – can go a long way to cooling the response.(7)
6) Bone Health
Bone density can be a significant concern for endurance and female athletes. The gut microbiota has been suggested to have an impact on bone mass via altering immune system function, impacting the hormonal regulation of bone formation and via bacterial metabolites that act as cellular messengers.(8) Experts believe the gut microbiota may someday prove to be a reliable biomarker for bone health.
7) Body Composition
Your gut bacteria can also greatly influence your body composition. A recent study found colonized the gut of healthy mice with the “obese microbiota” of overweight mice resulted in significantly greater total body fat mass compared to colonizing them with the “lean microbiota” of healthy mice.(9) Researchers believe certain bacteria may have an increased capacity to harvest energy from the diet, leading to weight gain.
The research on the role of gut bacteria and athlete performance is in its infancy. Modifications in diet, training regime and lifestyle factors like sleep may provide a novel way to influence the gut bacteria to support more robust, resilient and higher performing athletes.
Dr. Marc Bubbs ND, CISSN, CSCS
Want to learn more? Listen to expert Dr. Tommy Wood talk about the "Athlete's Gut" and common digestive problems on the Dr. Bubbs Performance Podcast...
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2) Ursell LK, Metcalf JL, Parfrey LW, et al. Defining the human microbiome. Nutr Rev 2012;70:S38–S44.
3) Clark A, Mach, N. Exercise-induced stress behavior, gut-microbiota-brain axis and diet: a systematic review for athletes. J Int Soc Sports Nutr. 2016; 13: 43.
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