Extreme exercise may trigger blood poisoning in people who haven't trained properly, a new study suggests.
Changes in gut wall
Researchers in Australia looked at athletes who took part in extreme endurance events. Examples of such events include 24-hour ultra-marathons and multi-stage ultra-marathons run on consecutive days.
The investigators found this type of exertion can cause intestinal bacteria to leak into the bloodstream. This can potentially lead to blood poisoning, they said.
Read: Blood poisoning: early diagnosis crucial
Blood samples were taken before and after the events, and compared with a control group. The researchers said these samples proved 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."
Once those bacteria are in the bloodstream, the immune system responds, causing inflammation throughout the body. It's a reaction similar to what happens during a serious infection episode, the researchers explained.
"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, triggers the body's immune cells into action," research team leader Ricardo Costa, of the department of nutrition and dietetics at Monash University in Melbourne, Australia, said in a university news release.
If not immediately diagnosed and treated, a bloodstream infection can be fatal, the study authors said.
Get a health check first
But these findings don't mean people need to sit out these extreme events. The researchers also found that fit and healthy athletes who follow a steady training programme to gradually prepare for extreme endurance events develop immune mechanisms to counter this threat.
"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," Costa said in the news release.
Read: Immune response
The findings were published recently in two journals. One study was in the International Journal of Sports Medicine. The other was in Exercise Immunology Reviews.
Anything over four hours of exercise, or consecutive days of endurance exercise, is considered extreme, Costa said.
"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," he said in the news release.
Costa advised anyone who signs up for such an event to get a health check first. Then, he said, build a slow and steady training programme don't just try to run a marathon a month after signing up.
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Image: Red blood cells from Shutterstock