What is stress and how does stress affect our bodies? ​Part 1: The gut and exercise

As the principal physiotherapist I have found patients wish to discuss the many ways that stress affects their bodies. A lot can be discussed during physiotherapy treatment on someone’s neck or shoulders.

What stress do we Encounter?

There are all types of stress that we encounter every day. Physical stress occurs when we lift heavy objects or little people (such as your children) and even when we have a long & strong bout of laughing. This can be positive in the sense that it acts as a stimulus to make our bodies stronger, or can be negative as when we tear ligaments in our ankles when twisting them while running at high speed.

Emotional stress can be positive or negative as well. Being busy often creates a positive stress if we know that we are accomplishing something worthwhile or helping someone we esteem. But being busy can create a negative stress if we know that we will not succeed or that the person we are working for will not be satisfied and will belittle us in front of others at the end of the day.

Just as our bodies have been designed by the Creator in such a way that great sadness causes us to cry, so to have our bodies been designed to physically react when we experience certain types of stress. Unfortunately the decay of genomes over successive generations means that our bodies, and the organisms within our bodies, no longer behave in an ideal manner.

What Happens with Stress and our Gut?

[1] Our bodies have a very large number of bacteria and other organisms in our guts, otherwise known as our intestinal system or intestinal tract. There are many different types of these organisms. Collectively the intestinal organisms can be called our gut microbiota.

When we have inflammation in our intestinal tracts, the numbers and types of bacteria in or guts change. Extrinsic stressors, including environmental stressors, antibiotic exposure,

sleep disturbance, physical activity, and psychological stress, may also play important roles in altering the composition of the gut microbiota.

The stress from excessively high long term noise such as that from traffic or industrial machines is a health hazard. In some mammals it causes a decrease in the number of bacteria group called Faecalibacterium spp. One of the members of this group, Faecalibacterium prausnitzii often decreases in numbers when a person has gastrointestinal inflammation, such as inflammatory bowel disease (IBD). So it is possible that excessive noise exposure may cause IBD due in part to the way it results in the decrease in the numbers of this organism in our guts.

What Happens with Stress, the Gut and Muscles?

The stress from physical exercise can be beneficial or harmful depending on a host of factors, such as the amount of enjoyment it creates, and the duration, frequency and intensity of the exercise. Studies have found that exercise can increase the numbers of F. prausnitzii (mentioned above), and this in turn helps protect against intestinal inflammation and thus IBD. However certain types of intense exercise, such as that carried out by athletes can have a negative effect. Several gut types of gut bacteria have been found to increase in athletes, including Bacteroides and Prevotella. The abundance of Prevotella spp was greater in cyclists who exercised more than 16 hours per week compared to those who cycled 6 to 10 hours per week. It has been suggested that the increased numbers of Prevotella was partly due to diets rich in carbohydrates and the number of hours exercising each week. This increase was thought to have helped the cyclists in some ways. However two other studies have shown that some Prevotella organisms may promote chronic inflammation.[3]

We are trained in diagnosing and treating problems in nerves, muscles, joints and pain. We are not dieticians so we can not provide the expert advice that they can. However, as physiotherapists trained in the science of exercise, we can help you with exercise related pain and dysfunction, decreased sport performance and decreased work fitness.


  1. Much of this information was based on this article: S Lobionda et al. The Role of Gut Microbiota in Intestinal Inflammation with Respect to Diet and Extrinsic Stressors. Micro-organisms 2019, 7(8), 271. https://doi.org/10.3390/microorganisms7080271. Accessed 29/08/2019
  2. LM Petersen et al. Community characteristics of the gut microbiomes of competitive cyclists. Microbiome 5, Article No. 98, 2017
  3. JM Larsen The immune response to Prevotella bacteria in chronic inflammatory disease. Immunology 2017 151(4):363-374

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