Extreme exercise, blood poisoning 'linked'

Extreme exercise such as ultra-marathons can lead to blood poisoning, Monash University researchers have found.

They monitored participants in a range of extreme endurance events, including 24-hour ultra-marathons, run on consecutive days.

Blood samples taken before and after the events showed that exercise over a prolonged period of time caused the gut wall to change, said lead researcher Dr Ricardo Costa.

This allowed naturally present bacteria, endotoxins, to leak into the bloodstream.

"Nearly all of the participants in our study had blood markers identical to patients admitted to hospital with sepsis," Dr Costa said.

The study found that people who are fit, healthy and follow a steady training program to build up to the extreme events, develop immune mechanisms to counteract the adverse effect.

"However individuals who take part in extreme endurance events, especially in the heat and with little training, put their bodies under enormous strain above the body's protective capacity," the study said.

"With elevated levels of endotoxins in the blood, the immune system's 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 it is not diagnosed and treated promptly."

The study is published in the Journal of Sports Medicine and in Exercise Immunology Reviews.

"It's crucial that anyone who signs up to an event, gets a health check first and builds a slow and steady training program, rather than jumping straight into a marathon, for example, with only a month's training," Dr Costa said.