Extreme exercise can cause intestinal bacteria to enter into the blood stream, leading to blood poisoning, says a new study.
Researchers at Melbourne-based Monash University monitored people who engage in extreme endurance events, including 24-hour ultra-marathons and multi-stage ultra-marathons, run on consecutive days.
Blood samples drawn from the participants before and after the events, compared with a control group, proved that extreme exercise over a prolonged period of time causes the intestinal wall to change, allowing the naturally present bacteria, known as endotoxins to leak into the bloodstream. This activates a systemic inflammatory response from the body's immune cells.
The study also found that individuals who are fit, healthy and follow a steady training program to buildup extreme endurance exercise, develop immune mechanisms to counteract this without any side effects.
When the levels of endotoxins in the blood is high, the immune response can be far greater than the body's protective counter-action.
In extreme cases, it leads to sepsis induced systemic inflammatory response syndrome, which can be fatal if not diagnosed and treated promptly.
The study, led by Ricardo Costa from Department of Nutrition and Dietetics, said, "Nearly all of the participants in our study had blood markers identical to patients admitted to hospital with sepsis. That's because the bacterial endotoxins that leach into the blood as a result of extreme exercise, trigger the body's immune cells into action."
Costa said anything over four hours of exercise and repetitive days of endurance exercise is considered extreme.
The 24-hour ultra-marathon study, is published in the International Journal of Sports Medicine
and the multi-stage ultra-marathon study is published in Exercise Immunology Reviews.