Exercise Can Kill: Marathons, Endurance Workouts Linked to Blood Poisoning

Ultra marathons and endurance events cause gut bacteria to leak into the bloodstream, leading to blood poisoning, according to a new study.

The finding of the new study comes after analyzing people who participated in fitness events, including ultra-marathons, and multi-stage marathons which span consecutive days.

"Blood samples taken before and after the events, compared with a control group, proved that exercise over a prolonged period of time causes the gut wall to change. This allows the naturally present bacteria, known as endotoxins, in the gut to leak into the bloodstream," said Dr Ricardo Costa, of the University of Monash.

"Nearly all of the participants in our study had blood markers identical to patients admitted to hospital with blood poisoning. That's because the bacterial endotoxins that leach into the blood as a result of extreme exercise, triggers the body's immune cells into action."

Researchers also noted that people who jump into endurance events with little preparation are most at risk.

Researchers highlighted that anything over four hours of exercise and repetitive days of endurance exercise should be considered extreme.

"Exercising in this way is no longer unusual - waiting lists for marathons, Ironman triathlon events and ultra-marathons are the norm and they're growing in popularity. 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 added.

The study also found that people who were fitter and trained over a longer period of time leading into the ultra-marathon event had higher levels of Interleukin 10 - an anti-inflammatory agent - which allowed them to dampen down the immune response which caused the negative health impacts.

"The body has the ability to adapt and put a brake on negative immune responses triggered by extreme endurance events."

"But if you haven't done the training and you're unfit - these are the people who can get into trouble," Dr Costa added.