Australia-based Monash University researchers have discovered that extreme exercise can cause intestinal bacteria to leak into the bloodstream, leading to blood poisoning, after studying volunteers who had participated in extreme endurance tests, including 24-hour ultra-marathons and multi-stage ultra-marathons, run on consecutive days.
Based on blood samples taken before and after the events, when compared with a control group, showed that exercise over a prolonged period of time causes the gut wall to change, allowing the naturally present bacteria, known as endotoxins, in the gut to leak into the bloodstream. Then, it triggers an inflammatory response from the body’s immunity system, explained Dr Ricardo Costa from the Department of Nutrition and Dietetics, who pioneered the study to identify a link between extreme exercise and its impact on gut integrity.
However, the study found that individuals who are are trained, fit, and healthy in the run up to extreme endurance events develop immune mechanisms to counteract this, without any side effects. Those with longer training like marathon participants had higher levels of Interleukin 10 – an anti-inflammatory agent, which allowed them to dampen down the negative health impacting immune response.
In extreme cases, it leads to sepsis induced systemic inflammatory response syndrome, which can be fatal if it is not diagnosed and treated promptly, he warned.
The study found all the participants had blood markers identical to patients admitted to hospital with sepsis, which was due to the bacterial endotoxins that leach into the blood as a result of extreme exercise and trigger the body’s immune cells into action, said Costa.
The 24-hour ultra-marathon study, published in the International Journal of Sports Medicine and the multi-stage ultra-marathon study, published in Exercise Immunology Reviews, both by Dr Costa’s team, back the guidelines for people wanting to take part in extreme endurance events.
Some of the guidelines include getting a health check first and developing a training program that builds fitness and endurance progressively to meet the stresses and strains of the event. Dr Costa advised that anything over four hours of exercise and repetitive days of endurance exercise is considered extreme.